Battery Revolution Clubhouse Recording - Residential Energy Storage Systems

0:00Transcript

0:00Hi everyone, welcome to Battery Insiders. This is episode number 61. I'm Miriam, I'm co-hosting here with Simon. And Simon, do you want to give a bit of a word about Battery Insiders and the speaker that we have today? Sure, happy to. Thank you, Miriam. Yeah, no, as I said, Miriam, we have this Battery Insiders podcast and we have been covering all kinds of different topics over the last, you know, I think over in total, I think 100 even episodes. But yeah, the more formal one 61 and covering all kinds of topics from, you know, very nerdy battery topics from recycling, production, different technology, solid-state, all kinds. And today I'm actually really glad that we have Yaa with us who is, I would say some original in some ways. She's been also in the earlier days. And I think it's a really fascinating work, especially also related to residential energy storage, which is the topic of the day. And they're very excited to have you here and over to Yulia to introduce the topic. Thank you, Simon. Thank you, Miriam. Thank you for having this opportunity to share some insights, ideas and work. We're working on the residential energy storage system. So it's a good moment to just start this topic. I can introduce some background.

1:19I think this is how it works, right? That'd be great. Thank you. Yeah. Thank you. Okay. So like when we talk about residential energy storage system, the first question to ask is, why you do this? Why didn't we have this before? And we are looking at the solution at the moment. The trigger point is energy storage. I mean, there's energy supply shortage. Everyone has the individual understanding or piece of the news to catch this information, what is happening in the whole world. And we want, we all know, like we want to make use of this renewable energy, like solar energy, using the PV modules of the wind energy, how to, how to transmit this, how to help this into our daily life in a more practical way. This is how the residential energy storage come up. And because it will work together with the PV modules that it installed on top of the rooftop, even either on your own house rooftop or on the community, or like a buildings rooftop that can work with this as well. And also this renewal, this we call the RESS, renewable energy storage system is a battery system together. It will be responsible for the DC to AC inversion. That means the power output can directly to supply our household loads. So this is the general principle from PV to battery to inverter to load. This is the basic line. But on top of the basic lines, there are many different side options that can can be used to optimize the energy conversion, inversion efficiency, and to harvest as much as energy from the PV side. And to make this to even smart control the house load that consumes more power than others in our home to reduce the electrical bill of everyone. So this is the motivation. And this is also a target, this is a solution. It's developed towards. And for this kind of solution, the main players in the whole market, it's like Tesla, there's Tesla Powerwall, Tesla Powerwall Plus, and LG electronics like LG Cap, Huawei, then Luna, they call Luna products and Enphase. Enphase is quite famous for providing the microinverter that is used with PV modules to convert DC to AC on the PV panel side. But they also provide such solution, they call in charge. So this is our some players, but also some small players on the way to join this market. Okay, so that's that's a basic background information. And okay, I'm not sure if I should dive deep into the engineering or before that, I can share some of my understanding how can we understand, so suppose like there's such product in the in the market online market or in the real store market, as a user, how can we choose such a product? Or how can we make make a decision to buy which one and how to improve it or make it a safer reliable in our home? Is this like the interesting angle from the audience?

5:08I'm very, very curious about that angle. Yeah, yes. Okay, thanks. So okay, let's suppose though, if we okay, if they say such kind of product like Tesla Powerwall, LG cam, Sonnen are in charge in the market, we want to buy such a product. And there is some rules, our performance indicators. And I summarize this as a full CS forming the number four, full CS. So that means that before C properties, and the one S, the first C can be understood like it's capacity, like we need to check the battery storage capacity is like 10 kilowatt hour, or five kilowatt hour, or seven kilowatt hour. So this is the first C, the next C will be the next C will be this is the C read. This is a this is engineering word for it actually means like how much power we can withdraw with this storage system. For example, we have a 10 kilowatt hour residential storage system. And the power we can withdraw every time we we use it, or we charge it or discharge it from such products can reach maximum to five kilowatts only for such kind of products. There are many reasons behind but the main reason is safety and reliability. So that means why it's five because five over 10, the five over 10 there is such a golden number 50%. So this is a this is a we call five 0.5 C. This is a engineering word for it indicates that you can actually be able to withdraw maximum 50% power of the whole capacity. If you have a six kilowatt hour system, the maximum power you can withdraw is only three kilowatts actually for continuously charging or discharging. This is the cycle C. And the third C is cycle ability. That means like a lifespan. So for example, like Tesla or most of LG Chem, they offer the lifespan of at least 10 years. But the 10 years is one thing you can you can understand of the cycle ability, I mean how many cycles you can do. The cycle, one cycle means one charging plus one discharging. Like every day, we use a PV module to charge such system. And then we will discharge the system either to fit the power to power grid for earning some money or we use a battery to discharge it for our household load. We can do many ways but this means one cycle per day. If we look at 10 years, that means 3650 cycles, this is the cycle ability of this battery system. But the battery cells, they can always do better than this number. Like for the lithium battery cells that used in such system, most of them are LFP, lithium pyrophosphate. Such battery cells capable of at least get to 6000 cycles.

8:33So that means it's more than 13 years, keep charging and discharging one cycle per day. But how come the manufacturer or the players only offer us users only 10 years? So that's because there is a degradation, sell to system performance loss and sell itself its own degradation. This double is the only reason behind. That's why we look at the solution. We look at we need to check about what kind of cell the system is using. They have this information in the spec sheet always like it's LFP or AMC. And we check the lifespan 10 years and we need to pay attention. If there is a small word, small note below the table to see you have to operate such system within certain temperature within certain power for getting such a lifespan. This is important information for users because not every player's it's capable to guarantee such good performance. We always play with the conditions like a temperature of the power with joint power per cycle. That will be the key factors affect the lifespan of the battery.

9:56This is the third C. And the number 4C is the cost. We need to check how much it costs, right? I think this is quite obvious consideration. This is how the 4C works. The last S is safety raise. This is due to the property of lithium-ion battery because lithium-ion battery is a simple understanding. It's an anode, cathode, electrolyte. Because it has electrolyte, when its temperature is quite high, overheated or short-circuited or due to other effects, the electrolyte gets leakage and it will induce fire recovery costs them all the way. So there will be always a safety risk in the system. So how can we, as a user, how can we understand the system we are purchasing is safe? There are certifications in the market that can help us to protect users at the first protection way. The certificate corresponding one for UL is called UL 9540. This is a thermal run away past the base certification. It makes sure even anything goes wrong with the battery cell or with the battery system within its enclosure. That means even there's a fire in the enclosure. There won't be any fire spread to the external of the enclosure.

11:30That means like as a user, we put such system, install such system in the in-home or in our garage or outdoor shelter, some somewhere close to us. Even there's fire within the enclosure, but we want to catch fire surrounding the outside of the enclosure. So we have enough time to observe, to see the smoke, to smell the smoke, to get time to escape or keep away from such dangerous item or we can put out the smoke, use fire pressure cylinder as well. So this is how this certification works. And there's also corresponding IEC certification, IEC 629335, but they work the same way. So this is a, this is usually the first thing we need to look into this spec sheet of the product in the market. And as an engineer working in such a product, this also will be the first test we will do for any such kind of product. And beyond this one, how to further guarantee our safety. If you, as a user, if you can just check about the IP rating, like if, like we all know, like, like our smart cell phone, now it's already IP67, right? But if you also pay attention to spec sheet of such system, to observe their IP rating to see if the IP, someone, some will be IP54, IP65, IP55, some different, they have different ratings, but pay attention to this number. If the more, the higher IP they have, the more safe the product will be because like I mentioned, the main reason of catching fire is because electrolytes, because that's where the, the smoke and induce the fire without electrolyte only smoke, that won't be fire. So that electrolyte of the, from the lithium battery cells, it is a trigger thing, trigger, trigger material for the fire. So if the whole product has a good, high enough IP, even there's electrolyte liquid within enclosure, it will not be leaked outside the enclosure. So that still reduce the risk of catching fire outside of the enclosure. So this is the second way we can further guarantee our safety. So this is the overall the full CS to understand such a product and to help users choose such a product in markets.

14:12So maybe I stop here well to see if any question or any other interesting points the audience wants to dive deeper into. Thank you very much for this overview. It's again, super interesting topics. Maybe also one last thing before we go, maybe also to Miriam and others for questions. Maybe you can also provide context because also where you're based and maybe some of the work you've been doing in the second just for other people to know you as well a bit more. I might put a help and to put into context. Yes, yeah. Oops, I forgot this part. Okay. Yeah, this is Yaa Alvi and I'm based in Singapore. So I used to work in Hong Kong for 10 years and I stepped into this lithium-ion battery or energy storage system industry since 2015 about eight years ago in a startup company in Hong Kong. And I was doing the product design, especially thermal design that links to safety at the moment when I joined this industry. And in this past eight years I have been dedicating to this work from the utility skill industry skill energy storage system now to focus more on the residential energy storage system. And now I'm working in a company called Maxon Solar and based in Singapore in R&D as principal engineer responsible and lead this residential energy storage system solution. So that's an overall background of myself. And if you are interested to know more things about such thing, or you want to know how this solution works together with the PV part, that's also where I can help. Yeah. Thanks, I'll pass to you. Thanks so much.

16:06Ma'am, would you like to go first? Thank you, Yaa Al, for the overview and the context. I know you mentioned a few things you mentioned the orientation or architecture of the energy storage systems for residential and you really, you really drove the idea of safety and how you choose materials and architecture to make sure that you can respond to a safety event. But my question is even more foundational than all of that, which is how do we get more energy storage and solar to residential? Is it the individual that usually is the one that has the onus of bringing solar to their houses, for instance, or is the market now working with, say, developers of new houses, new apartment buildings to install these sorts of things? Yeah, thanks, Ma'am. That's a very good question. So since I'm also working with a solar company, I think it depends on where we are, where the users are living. For example, in Australia, people install PV modules from the, like, they can directly purchase PV modules from Maxion. And because our company is a B2C, business to customer, business model, but different other companies, they may have B2B, then there'll be like some retailers or some constructors working in between to work on this such kind of final deliverable and help you install the PV module on top of your house. If I care for people like in Singapore, most people, most people stay in this building, right? And this building block, and then there'll be usually a central company that will be responsible to install the PV modules on top of such a building.

18:08So they will not directly contact with the users. Instead, they contact with the building block people or company behind the end to for such installation. So Singapore is different. It's quite different from that from US or US, Australia or some Europe countries. Well, yeah, that's how it is working. Thank you. Yeah, I see that, Ben, you've raised your hand. Ben, Tristan, would you like to go next and ask your question? I don't have a question at the moment. I just thought I'd hang out because it is super, I'm literally in the middle of installing my own PV battery. Well, it's installed. I'm just right in the middle of doing that, doing the mains distribution side of it now. So I thought I'd hang out, listen out, see if there's anything I can ask or, or jump in with because for the last few weeks, this has been my passion. It's been super, super satisfying to watch us transition up to the building one part at a time to completely solar and off grid. So yeah, I'll hang out if that's okay and get a feel, measure for the conversation. Okay. That sounds very interesting. Ben, do you mind I ask, what kind of battery, which which brand of battery start system you purchase? Yeah, sure. For your house? Yeah, so I've gone with Victron Energy as the, as the inverter system. So it's a Victron Quattro 15 kVA for the inverter charger.

19:32I've got 30, currently 30, but it's expandable to 900 and something kilowatt hours of BYD managed lithium-ion phosphate batteries, which I really like. They're nicely packaged. They're, you know, in a re-insuring metal container. They are self-managing, as you probably know, which is fantastic because they, they do nice things like report their maximum, you know, discharge and charge currents and things to the back to the system. Yeah. So I've just got, I've gone with BYD for the batteries and then panels. I don't care like any panels I can get my hold on hands on. They're all, as far as I'm concerned, it's just, you know, what's the, what's the, what's the cost per kilowatt or megawatt hour over their lifetime. So I just look at the warranty and the, you know, and the cost per watt, and then, you know, just take a view on it. But yeah. That's it at the moment. Okay. Okay. Interesting. Yeah. It's like for this. Yeah. I think that we, we can tell you, since you have this BYD, so, you know, for the residential energy storage system, there are usually two ways, two solutions. You can find two ways of solution. You can find marketing. One way is like BYD, Bbox, like it just, they just sell the battery storage system and you need to match it with additional or all compatible inverter on your site. And there is another way it's like, they offer you such a solution as a bundle solution with already compatible test, after testifying to you, whether together with a storage, especially they, they will enclose it together with a nice industry office, say the design. So that's the two, two types of ways you can find.

21:12Thanks so much for sharing your experience, Ben. I did have a question then, and this really ties into also your experience, Ben and you know, what are the economics like of setting up a solar and setting up a battery? What's the payback like for individuals? What's the payback like for residential versus other types of, sorry, you know, suburban homes versus other types of residential buildings and so on? Okay. Yeah, maybe Ben, you want to speak first? I saw you just a minute. I'm always going to let you go first. It's your room. So I'll just wait for you. Okay, thanks. Yes. Yeah, because I also wonder like where, where Ben's living, because it depends on the, the payback years. Okay, there is a, for example, we offer such a solution, you only have a calculation model. So I can calculate out the payback years, several factors we use. First is location and the user habits. So the locations and location depends on, will determine the stability of the power grid from that location, geographic location. And also we can see the solar irradiance curves, you know, for the United country or United place. And with all this historic solar irradiance daily, we can calculate out the payback years based on the, let's see the PV modules that you choose because PV modules, they have the current voltage curve as well. And based on inverter, you choose because the inverter, they have this different power rating. Some are like six, three kilowatts, some are five, some are 10. So this inverter performance efficiency, and together with the battery storage system, you choose in terms of the power, power rating, the alpha continuously capacity, capacity, it's also one factor, but we usually use some power and together with the chemistry, whether it's a LFP or LMC or, or other chemistry recipe behind, and together we come out to this number, five to 10 years are all possible. So it's a case per case calculation. Yeah, I can second that. I mean, I've put in the link, the the solar calculation tool I use PVGIS, certainly works for the UK. I haven't truly validated it. I don't 100% trust it.

23:44I don't 100% trust anything. So I'm currently split testing panels that are horizontal on the ground, for example, because when the sky, a lot of the time it's diffuse horizontal radiation here, we have, we have, it's very cloudy, right? And as soon as it's cloudy, then pointing the panels, it seems logical to me that pointing them directly at the sky is better than pointing them towards the sun, because there's more bright sky to obtain energy from. But I'm validating that that's not what some of the solar prediction tools say. But I don't trust them. So I'm checking for myself. For me, the panels, so in the UK, 52 latitude, with quite cloudy conditions, the panels, the raw panels pay off in one year, then, you know, I do everything myself. So I don't know what you'd have to pay somebody to mount them. Presumably, that would double it. So my cost is 33 pence per kilowatt, sorry, 33 pence per watt, per watt for the panels, you're probably going to add that again, about 10% more than that. And then again, for cabling, because every time you have a string of cables, you need to run, you know, run some cable back. So you've got to add at least 10% for the cabling. And then you're going to double it at least, probably triple it by the time it's installed by somebody else with a mounting system. So that could take a one year payoff to three years for the raw panels. And then you've got the rest and this is in the UK, if you're in Calipari, if you're somewhere else could be a lot longer.

24:59But then you've got all the other parts of the system, like the inverter charger, the batteries, which are certainly not expensive. And the bottom line for me is I calculate roughly that the power paid if I consider over the next 10 years, from solar is about one pence per kilowatt hour, which is the typical unit of electricity. Energy that's gone by the battery is probably about four pence per kilowatt hour, because the battery is expensive and degrades over time. And for context, so one p direct direct use solar, four p via the battery. And then for context, our grid nighttime cost is 20. And our grid daytime is 40. So yeah, a lot of money to be saved for for us. There's another factor, of course, it's not just the payoff. It's the fact that we now don't need the grid, full stop, we can just disconnect. In fact, it's more expensive to pay the daily standing charge for us now than it is to just continue to invest in solar. So it's not even worth paying the connection fee of 50p a day. So yeah, our plan, stay connected because we're going to sell energy back to the grid.

26:03Oh, that's interesting. We don't need to be connected. Okay, interesting to know that because you know, like, as also we know, in some like, your countries, the country offers some tariffs. If you make sure that the house loading is using the power directly from PV, that means you have a proof for the power flow is directly from renewable energy PV to your household load. Instead of like, you see storage PV first, and then you use that battery together with a grid to supply your household load. So this the directly usage PV to load will give a higher benefit from the countryside. This is something information we capture at the moment. That's also, I'm not sure that the battery storage you are using, but Benbot for most of residential battery storage, they are now prioritizing the working mode. So the first working mode is called like self consumption. It's like even we have PV battery household load, the backup load and power grid all connected, but the priority will go from PV to load. And then the second will like PV to battery, then the, then the like, see battery to load. And the last one is the PV to load, or sometimes the battery to the PV to load, they're competitive, give the user to option, you can choose like when to discharge the battery, but no matter what the PV to load, the always the first one. Is that the case on your side? Well, sorry, it's taking me a second to unmute because I'm drilling large holes in a water amount, a big AC distribution box. So in my case, it doesn't matter. The grid is always going to charge me the same. You've got a little bit of choice. Some people in our country have flat rate 24 hours a day, most people have flat rate, maybe 30 pence a kilowatt hour to buy in this is. And then the most asymmetric I've seen at the moment is the difference between 10% for seven hours at night, is 10 pence a kilowatt hour. And then the rest of the 24 hours would be 40 pence.

28:21So one great advantage of the batteries, of course, is we, you can switch to night rate only and only buy the cheap electricity and run off the batteries all day. When it comes to sending electricity out, they don't care in the UK really, wait, how you made that power, they're gonna, you're, I'm gonna go once I'm MCS micro generation certification scheme certified. Um, I will just go to the highest bidder for the power going out now, whether I've generated that by solar, I don't know what the strict regulations are, to be honest, but pragmatically, because I'm using Victron and it's all very open source, I can do what I like with what I, what I, where I direct energy as solar comes in, I can consume it directly. I can heat hot water with it. I can store it in big hot water tanks, I can charge my EV, I can put it in the battery, I do whatever I like with it. The grid will only care what the net export is. So we have a net export limit of 17 kilowatts, based on the size of the, you know, the infrastructure that feeds into the house.

29:20And they'll just pay us for each kilowatt hour. And that I don't think it makes any difference. Certainly, technically, it makes no difference whether that was generated by the sun, whether I'm discharging the battery into the grid, which I'd be a bit crazy to do, but I could, or whether I'm running a diesel generator and pushing it to the grid, which would also be crazy, because it would cost me more than it would to buy a lot, lot more than they pay me. So, and my system is all DC coupled, which means that all the fun stuff happens on the battery side. It doesn't really matter how that the AC is made by the inverter, and then everything, it just goes straight to the grid. So I think the short answer in the UK is it doesn't matter. And then, internally, I do what I think is most sensible with the power. And, you know, do some very simple programming to say, hey, look, we've got more solar than we know what to do with. Let's charge the car, or let's put it in the water tanks. Okay, I got the ban. Okay, okay. So I think, yeah, that says different countries may have different policies. But yeah, okay.

30:20But you know, like, yeah, for some bundled residential, they call, they can name it in different ways. But for such a residential bundled solution, storage plus inverter that can be DC coupled, is it coupled or hybrid that they adapt to different users, the users who already have PV modules or who will choose PV modules now later, but maybe now it's like not now. So some different stages of user habits that's going to have. But when coming to your case, I really wonder like, how you look at this reliability or warranty of this battery system, when you purchase it, they do demand a lot because I'm working on this product. And we have many, okay, not many, but we do have some like technology, engineering difficulties of, okay, if extracting accurate model for warranty, or lifespan, sorry to say that. But this is, this is true, even for Tesla is the truth. It's the same situation. I want to ask, as a user, do you really care a lot about this when you choose them and you use them? No, not really. I have multiple batteries, I have multiple inverters. And I can swap any battery out, I can swap the inverter to a different, different inverters, I can rely on one of the two, I can rely on one of the two battery banks, I can switch to a different manufacturer of battery, a different manufacturer of inverter, a different manufacturer of panels, I can go where I like with it.

32:02And what's written down, I say, I fairly well trust what's written down on paper with regards to the warranties. I choose good suppliers who should, you know, honor the warranties. But the payoff times are so good when I'm self installing that, you know, I mean, I'm in the money, as it were so quickly that even if it goes wrong, if one element goes wrong in five years, I'll swap that element out and carry on. And in general, I'm going to try and have two, two versions of every element anyway, as I said, to redundancy through the system. So it wouldn't take me down losing one of say one of two. So I'm not overly fast, but I do think warranty is important. I mentioned that earlier when I talked about solar, you know, I'm effectively saying what's the how many years is the warranty, multiplied by what's how many watts is the panels, multiplied by about 1000, you get about 1000 hours of you get the equivalent of 1000 hours of full time, full full power use out of panels in the UK.

32:58So 1000 watts of panels give you about a megawatt energy over the year. So that's it, I just multiply the 15 year warranty by the number of watts. And then, you know, that gives me one number. And then I just say, well, how expensive is it, and divide the two together. And that gives me an idea. And I'm kind of distrusting that they'll people on other warranties. And if the odd panel here and there goes wrong, well, doesn't really matter. You know, if I've got a string of 10 panels, and one panel fails, well, I can replace it with any panel that is a similar spec, you know, without it being detrimental. So it's pretty, pretty resilient, I think, in that respect, but I'm quite unusual, and I do it all myself, I do the AC cabling myself that all the DC work, everything, I would like to teach others how to do it themselves, because I think we become too reliant upon our installers, and we don't really know what we're buying and what the right solution is, and actually how big a system we need. I'm my system's very modular, it's, it's starting off relatively modest for the size of the house at just, just 10, 12 kilowatts of inverter and 30 kilowatt hours of battery. Whereas an off-grid company would say I need, you know, 24 kilowatts of inverters and 90 kilowatt hours of batteries, and 45 kilowatts of solar, I'm, my system's modular, each system fits on a standard sized board 1.2 by 2.4 meter wooden board. And I can add modules, meaning more batteries, more inverters and more solar charge controllers, as I need to, until I get up to the size that I need to be, while simultaneously trying to reduce my demand. Because as soon as I'm, you know, responsible for my own power, I'm being even more, I've always been cautious about power use, but I'm being even more respectful of wasted power.

34:36So over the next year or so, I expect my generation and self-sufficiency capabilities to go up, my solar capacity to go up, but also my usage to go down and they'll meet at some point, rather than just saying, Hey, historically, I've used this much, let's just put in a massive system that can replace that historical usage. That's not really moving us forward in terms of it's not lowering my consumption. So I'm looking at both sides, demand management, lowering consumption, and becoming more self-sufficient and saving money. And it's all really, it's great. It feels really good to sit down in an evening and play a video game, knowing that all that energy came from the sun, plus a bunch of embodied energy and all the stuff. But anyway, I'm waffling on. Great. Thank you so much for sharing. And also before I would like to go to Vern, who I think looks like from his bio also has quite a lot of experience in the space. Maybe one last quick question also just for you, Ben, and maybe also you have any thoughts on it, just on the sizing of your battery. Like what has been your approach on like, you know, to figure out like how much battery capacity you need for your installation or for your setup? Just giving Yars some space issue.

35:33So the size of battery in order to feed a certain inverter. So it all goes together. That's why I'm doing this in a modular way. I put together a board that's 1.2 by 2.4 meters for myself, as I say, that has 30 kilowatt hours of batteries. Any smaller than that would not feed the peak current requirements of a 15 kVA inverter. So that's the first question to me is you cannot put a battery that's too small on a certain inverter because it will literally, the inverter will overload the battery. A larger a battery gets, of course, the more current or power it can supply because most lithium batteries, basically the rule of thumb you could say is that they don't really want to be charged or discharged in less than about an hour to an hour and a half. So it doesn't really matter. If you see what I mean, the bigger the inverter gets, the more power you want, the bigger the batteries have to get beyond that minimum threshold of battery, then it's entirely up to how long you need to be storing to get you through bad weather. So the last four days in the UK were pretty rubbish. Well, not the last four, but you know, early last week is really bad. Several days of really really rainy and dark, still generating solar energy, but not quite enough to keep up. So every day the battery is 20% lower, 20% lower. And of course, a battery twice the size would just extend that period. So, but the other option is useless. So, so the short answer is big enough for the inverter. And then beyond that big enough to get you through the lulls in the wind or the solar or whatever your renewable is. But that's my thought.

36:55Yeah. Thanks. Thanks Ben. I'd also like to add some, something on this question. So usually like we choose the size of storage or inverter or as a bomber solution. It's similar like the way we choose the EV charger. Can you know in the market, we know there's like a single phase EV charger, three-finger, three-finger charger. So that's a power like seven, 12 or 21. So it's basically why the number is there like that. It's, it's from the miniature circuit breaker. We're using the household and also our household voltage. Like I'm staying in Singapore, my household is a single phase and the MCB we call the miniature circle breaker. MCB can go up to 32 ampere, but we also have some small one, like a 60 ampere. So this is the way with, when I can kill it, you type the 230, 230 volt single phase with this 32 ampere MCB, you get this close to seven. So there's a power, up limit power we are looking at for such a residential energy storage system. Then we look at the battery capability, like I mentioned, it's usually 50% of the power continuously output for safety and reliability concern. There are types too. So that means like you choose around the 10 to 14 kilowatt hours energy capacity will be enough for supplying such power, seven, five to seven kilowatts. If you choose, like I choose a 12 or 14 or 15 or above 20, that's not necessary. It's overrated. This is how it works at the moment. Three phase you may need more because if you're three phase, then the power will go up to 20, around 21 kilowatts. Then you, when you tap it with two, you've got to actually 40 kilowatt hour. Then that means you need more battery capacity there. Well, it depends on whether you're going to use this 21 kilowatt altogether or actually use this in separate location, like a kitchen, a bedroom, or second floor, certain floor basement. They're all different MCB. So that's different in counting based on the real application scenario you are looking at. So this is how it works on our side now.

39:19Great. Thanks for sharing that. I think we just lost Vern, but then maybe coming a bit later, I think it was in the car as well. Maybe I just want to use this chance as well to invite anybody else who have any questions, any thoughts on this topic of residential energy storage to come up on stage as well. I think there's some very knowledgeable people here. Also different perspectives, I think also great from Singapore, as well as the UK, if I'm correct then. And yeah, we want to invite everyone also to get up to ask your questions. Otherwise, also in the meantime, maybe I can talk a bit about or ask a bit about degradation. I think you start talking about it, yeah, earlier, some of technical bits, maybe if you could expand a bit on it, like your experience, what you have seen in the market, maybe also the markets you have been involved in, and of course, also anybody else like Ben, be free to add on afterwards as well.

40:05Okay. Yeah, sure. Okay. For degradation, we look at the degradation, we need to understand like, what are the main influencers for the degradation of such system. We look at it from battery cell first. For lithium and battery cell degradation factors are temperature and state of charge means their voltage level during charging and discharging and the current withdraw from the battery. But most of the important one is the temperature. The battery, I believe most of them, most of you are aware of the optimal golden temperature range for lithium battery range from 15 degrees to 30. And if the battery is working within temperature, it's again, we can get the maximum of this lifespan out below 15 or above 35. There'll be like some chemistry, chemical phenomena happens like this solid electrolyte in the facial layer of the anode. It will start to dissolve into the electrolyte. This is, then it will get damaged. Once it gets damaged, then like there'll be some materials flow between the anode and cathode. And this whole process will increase this because solid pinball interface layer. So that will stop in the way because, okay, and I'll put it in a simple way. This battery because lithium can flow within the bat within the from the canal to add castle, it can flow. The more lithium ions flow within this, like two electrodes, we get more like a power during charging on this charging. And the degradation means like there are different barriers.

42:03Some chemical phenomena that happen within the battery that stop. It is slow down the flow of the lithium batteries or the block the number of lithium ions that to be flow. So that you have two ways to understand either the lithium-ion low speed becomes small, slowly, or the lithium, the number, the quantity of the lithium ions that can flow get reduced. So no matter which way, in the end, you have less power, you have less energy capacity, I mean, usable energy capacity from the whole battery. So this is the battery level degradation. And from battery to system, this is a different understanding. If you look at the battery, the degradation comes from chemistry, especially from chemical electrical chemical reaction, then from the battery cell, the battery system, the degradation comes from the system integration design, like we put a different cells, numbers of cells in series in parallel, and the enclose them in one aluminum, like alloy enclosure, then integration design, able of induce the system level degradation. So this is where we say like a thermal design, mechanical design, electrical design, all of them can can trigger this degradation, but the thermal management design is a key one, or it's the most influential one. And this is due to like, for example, we have 20 cells connected within the system. But another 20 of them have the same temperature, or same voltage while working, just like we have 20 people in class, now the 20 of them have the same height, some are taller, some are shorter. So this is this is their property. And this is how the weight we call the battery management system, the BMS, then to charging is charging, but it can't manage in the perfect way. There'll be always some battery have a higher we call state of charging, a higher voltage level, some have a lower voltage level, even the battery management system is power electronic devices trying to balance them as much as it can, but it can't be avoided. This is one thing. And the other other is this temperature, because the temperature distribution, the temperature of the heat transfer, is beyond how this BMS control. You BMS can control the voltage of all the 20 cells, but you can't, the BMS cannot balance of this battery cells. The temperature depends on how this is, this 20 cells are, the layout of them. For example, extreme case, we put one cell in the center, and like a circle, we put the other cells through surrounding them, circle layer to layer until it's 20. The height, the hottest one must be the center one, the middle one, because it's keeping being hated by the surrounding cells. Every single cell is releasing heat during working during operation. So we can't make every single cell working on the same temperature.

45:35There'll be always a maximum and the minimum temperature. But it's said there's no existing solution to balancing the temperature of the cells. It relies on the some management design, but it's it's not perfect. It's not dynamic design. It's a static design means put like some thermal interfacial material, or you put a fan or some like a Tesla using liquid cooling or some other company use the fan to airflow to cool down, no matter what you do. Once you put a thermal management solution, it's done. You can't adapt it dynamically to the temperature of the amount of different cells. In that way, you can't, there'll be always like a cold temperature drop among all the cells. And that's where the main system degradation comes from. And to measure this kind of degradation, there's an item. You may see this in the spreadsheet. It's called the ISOH state of health. And this state of health marked in the data sheet of the products is only systems state of health.

46:49But the cell level, battery cell level, usually they are able to offer a higher state of health. But due to the cell to system degradation, the system levels to the health is always lower than the cell level. And this state of health can collision. It's the most challenging technology problem in the current industry, or in the matter in universities or in companies. This is the most challenging thing. People are trying to use like a big data machine learning model, basic physics, electrical circuit model, electrical equations, thermal equations, chemical reaction equations to try to find some accurate cancellation for that. And also like a filter model to get some passing data to correct this value dynamically in a real time way. But unfortunately, I'm telling you guys the truth is still far away from the real true accurate value. So we're not there yet. This is also something that's affecting, influencing the lifespan of the whole such system. That's why the PV modules, we can have a warranty.

48:10I'm not sure, but somehow they can go up to 14 years. But for this kind of inverter, we can have 10 to 20 years based on the inverter, string or microinverter. But for battery system, up to 10 years. It's really hard to jump over this lifespan. And this state of health is the biggest thing, the first barrier to conquer. Thank you. Yeah, I did have a question for you about the type of battery battery. One should choose. So you mentioned lithium-ion, but you also mentioned flow batteries like LFPs. I've been seeing some vanadium flow batteries online for residential. How do you know what type of battery to choose? And why are there specific benefits for safety for one type of battery versus another for economics and so on? Thank you, Maria. If I have questions, okay. Okay. So lithium battery cells, the chemistry, the most popular one are LFP and AMC. LFP is lithium pyrophosphate. AMC is nickel, magnesium, cobalt oxide. So they both indicate the material for the castles of the battery.

49:25The anode, some use graphite, some use combined material, but we are looking at the castles because that's where it dominated the energy capacity. So it depends on the application. For example, I give example, like EV, electrical vehicles. If we're looking at the application that needs high power, it means like if we want to withdraw the power. Okay. This is where we use the say, it means like the power withdrawal from the system over the energy capacity, like a 10 kilowatt hour system, if we withdraw power, 10 kilowatt, means you are using this system at this one save rate, means like you can, you need to charge this, charge the system one hour for 10 kilowatt. So I need to introduce this, this, this, this safety concept first before I continue the other information. So let's say 10 kilowatt hour system withdraw the power of 10 kilowatt. That means we are using it at one save rate. That means when charging it at 10 kilowatt hour, the charging time will be one hour, 10 over 10, just one hour. If we withdraw this system at 5 kilowatt, the save rate will be 0.5 C, 5 over 10.5 C. This means like, sorry. Yeah. That means like a one way. When we're charging this, this charging this, this kind of system, the charging time will be two hours. Oh yeah. Continuously.

51:05That then coming back to this question, we talk about electrical vehicles. This, uh, a series, we, it's required to go up to two, two series to full series. That means like if we have, let's see, uh, 10, I mean, 10 kilowatt hour is not enough for electrical vehicle, but if we have a 40 kilowatt hour, battery system, then we, we actually need to withdraw, um, let's see, uh, at least the 100 kilowatt or about 100 to 150 kilowatts during charging, especially during char, uh, during discharging, that's where we can get the, um, uh, acceleration speed and, uh, um, running speed. That's where the power from actually the power can be four times two to energy capacity. However, for energy storage, this stationary application, it's different situation. This is a state-rich requirement that drops to 0.5 C to 1 C. That means when I, when I have this, uh, 10 kilowatt hour system, I just need, I just need to, um, make sure we, I'm a five kilowatt to 10 kilowatt. That's already enough for energy storage system. Then back to residential energy storage system because the, I mentioned a miniature circuit breaker, circuit breaker we're using at household. So we don't need to go up to 10 kilowatt hour for the single phase, uh, um, uh, home because it's overrated. So that's where we use the five kilowatt. That's where most of such system in the market is a 10 kilowatt hour. Okay. Then for, because of this C rate requirement, because of all this, like a withdrawal power change, you don't need to go for high power battery for residential application. We actually want, uh, uh, more safe, uh, battery chemistry. This is the different, uh, motivation, um, from the electrical vehicle, but EV part, we want high power, so we want high power battery. Although safety is also important, but for residential, the safety is, uh, it's obviously overrated any other things like this high power energy capacity or power density. That's where, uh, we, you, we will choose or prioritize LFP in the residential or any stationary app, energy storage application, but we prioritize NMC for the electrical vehicle or EVASO application.

53:52So, uh, sorry to, uh, to use such kind of engineering items to explain this because I think if you can catch this items concept, then that's how you can understand the know-how of, uh, why we choose this, uh, different cells for different applications. But I mean, I hope, uh, answer our question. Yes. Perfect. Thank you. It could be a good opportunity. If anyone in the audience has questions or any additions, um, to the conversation, please raise your hand and we'll add you to the audience. We'll add you to this, uh, to the audience stage. Or maybe also what you have absorbed in your regions, right? Because I think quite a few countries right now, I talked about increase of use of stationary energy storage or residential energy storage. And I think also in Germany, we see quite a bit of a ramp up right now. So I'm also curious if anybody has seen something else in their region. Sorry. Uh, I didn't, I didn't capture you Simon. So what, what do you want to know more about voltage? No, sorry. It's more about maybe also incentive programs or how the adoption in different regions, because I've seen now in Germany, there's more kind of support schemes, I think, getting created. And I'm wondering in Singapore, is it like encouraged by the government, the people's install it? How does it work? Okay. Um, okay. For, okay. For energy system as a whole, especially for this utility industry level, Singapore is quite open, uh, and to have some government support, like, uh, they have an island, uh, drew like because it's called drew island, like it's remote from residential area. They offer the, um, the place for test, testing this, uh, several, I think 100 to keep mega water hour energy source system with, um, containers. That means each container is about one megawatt hour, 100, um, about, about 100 of them stay there. This is the, this is a, this is not for residential, um, level. It's more like commercial industry level, but for residential level in Singapore, uh, we actually, I don't see any, um, uh, any popular usage yet. I know, I know you, in Europe, especially in Australia, it's, it's quite a popular, it's a, it's like, it's a, it's a trend, but in Singapore not. Okay. One thing is like, Singapore people, you know, it's like, the house quite dense. Not, not too many people living in the house, but I do see, what I do see is for the, we call landed house in Singapore, most of the landed house, we have PV modules, it's data writing. So they may go for those users may go, go for, uh, combining with a residential and such storage system, but the market in Singapore for such residential, uh, storage system is not that big compared to Australia, um, uh, UK, uh, Germany, Italian, Belgium. That's where like, yeah, I think that's where the market is. Okay. Thanks for sharing. Is there maybe something you observed in your, you know, your career and like your development in the sector where some, like a big misconception, you would say, where people think in some certain way about it and people keep asking you and, you know, it's actually quite different. Um, okay. I think it's like, uh, um, this kind of product is quite new for, um, really for us, for all of us. And, uh, I think that most of users, they just, uh, they just look at the, look at the, the, yeah, they choose products from the, the manufacturer, the brand. And, uh, uh, there's, yeah, I think like it, just what Ben has shared. Uh, I asked Ben about the, the warranty, but he does, doesn't care about the warranty as long as it works well. And, uh, also since people haven't, uh, come up more, uh, user experience problem yet, like, uh, recycling, how to recycling this battery, um, after usage and, uh, how can we, um, okay. How can we make the optimal usage of the system or, uh, some like a digital interface, uh, that may trigger the change of our big life, you know, okay. I'm talking about this, uh, because, uh, uh, there's some conversation on discussion in the industry about virtual power plant. Uh, some people they're seeing this residential energy system, uh, together with, uh, PV modules and other similar, um, like EV chargers, uh, uh, heat pumps, all of this can become, uh, uh, like energy level Facebook, sorry to say, I mean, but this is some conversation in the industry that has happening, uh, like Facebook energy. So all the people, users who purchase this system or one of them, and especially using this digital interface, like app or dashboard, they may become a member of the community of this virtual, and, uh, there'll be a lots of things to do there. Um, we, they put it to like, uh, imagination, uh, mutual energy sharing, energy renting, um, yeah, as a whole, we call energy service, but something like that, that's, uh, that's something like, you know, obviously it's, it's a direction, but we don't have a clue how feasible it is and how we practically, um, much to all that, but, uh, that might be the, the Samsung, like see, some cloud in the sky, uh, with a little touch from industry level. Uh, yeah, I'm not sure this covers your question, uh, Simon, but, or, I'm also, I like, like to get more questions from audience regarding some of your understanding or do worry about to something, uh, we have such a kind of water power plants and have other people connect and let you share the energy to your neighbors.

1:00:27We will get scared of such things to happen. Great. Thanks. And for free, also maybe Ben, if there's something for you learning and then I'll add to Mariam to have a closing question as well. What are some of your biggest learnings Ben in this process? Hmm. I dunno, it's all learning. Some of the biggest learnings are the smallest things. Um, yeah, I've been using chat GPT-4 a lot to try and work out what on earth to search for. Um, it, you know, it's read all the regular, the electrical regulations and things. So, you know, I, conceptually it's very easy to run a cable, 75 meters from one building to another, but it's got to meet all the regs. It's got a bit of carry the current. It's got to not drop too much voltage. It's got to, you know, it's got to be properly terminated at each end and it's got to all, all be done beautifully, especially if we're going to be micro generation certified. So there's a lot of little learnings like understanding what a cable gland is and what size it needs to be and how to terminate steel wire armoured cable. Um, there's, there's going to be a lot to, to the, to the previous point about integration. There's going to be a lot of learning, uh, about how to make the systems talk to each other. So the Victron to talk to the car charger to talk to, uh, loads in the house, such as immersion heaters and the like.

1:01:38Um, I'm personally going to do that using something called MQTT, which is a digital messaging system, but not yet. I build all my systems in layers. Um, so that the bottom layer, the basic layer works regardless of any of the clever stuff on top. Um, so at the moment I'm at the base layer, just building to make sure it's reliable and does it properly sized and does what it needs. Um, I mean, there's a lot, there's a lot of, I mean, what is surprising? My biggest learning would be that it, that we can, we're fairly unconstrained from a space perspective. I should say that we have a lot of land, a few acres, but even just using a small amount of area, tens of square meters, we are able to be power self-sufficient and we're heavy users, 60 to 80 kilowatt hours a day. Um, we're able to be power self-sufficient even when it's cloudy. And I'm confident that we're going to be able to be able to be a power self-sufficient all year, even when it's cloudy. Um, which is quite amazing.

1:02:31So I'm reframing solar panels as just daylight panels. Of course they produce a lot, lot, lot more when the sun is shining, but, uh, even on a cloudy, rainy, dull day, they're still producing a thousand Watts, something like that. Right, right now, as I speak, it's bright, but completely cloud overcast and we're producing over 2000 Watts, uh, which, you know, average through the hours of daylight is plenty of energy. Uh, and this is only a fraction of our, of our capacity that's ready to go. So, so I'm quite encouraged by that. I'm pretty encouraged that we won't need the diesel generator to be off grid. Um, I'm encouraged by, and I've learned a lot about how you can do things yourself. And then if you're lucky enough to have a local electrician come and certify your work, um, then that, I believe that's possible for anybody who's willing to put the time and effort into learning. Um, but of course you're going to have to do things nicely, you know, talk up your nuts properly, mark them when they're, you know, everything, just everything about insulation requirements and regulation requirements and earting requirements and cable sizing. It all needs to be done properly.

1:03:31And if it's done properly, um, you can be the master of your own power. So yeah, I've learned a lot and I've got a huge amount more to learn, learn the most of course, when things go wrong. So almost, I should probably be wishing for more as long as they're survivable. Ben, I want to ask like, you know, like this Niger, uh, I think in this year's CES, Niger, uh, released their new product called the Pulse. The Pulse is, it's, I think it's, it's another company called SPA, work together with LGCAM, SPA. So they, they, they both are offering this, uh, smart panel that can, uh, control our circle breaker of the household load in a separate way. So together with storage and the PV, um, and I'm not sure you, you have this, uh, um, plan to also purchase such a panel to our home and also to play around. Oh, are you interested of the such company that you, you, you mentioned about MQTT, I mean, it's like, uh, okay, there's a data flow, right? The protocol button, when you have this, uh, your, uh, either dashboard or app, um, you, that make you able to, um, control the household where the, for example, you want the kitchen with PV, but you want the fridge with PV, um, you want, uh, air conditioner with, uh, a battery. You have this different, uh, flex, you have flexibility to, to, to choose this, uh, um, power allocation from other system you have. Are you interested on that or you have plan to try that? Um, I'm not too interested in diverting power physically to different places, not physically, as in, I'm not going to run any extra cables, a separate circuit to the bridge, for example. Um, and I definitely don't expect to have two supplies from the battery inverter from the shed. If you like the power shed, I don't expect to have more than one physical supply into the house. Um, the way that I differentiate solar and battery would just be by switching. And of course I can do that. I wouldn't typically do that at a consumer unit level because that's a bit indiscriminate and it's throwing a lot of circuits off. You know, our fridge is also plugged into a whole bunch of other things on that circuit. I mean, I could do that using what you're mentioning or Shelly relays, or there's a lot of companies that make remote configurable relays. Uh, I tend to do it at more slightly more granular levels. So if I want to turn all the sockets off in the living room, when I leave that at night, then they would be Zigbee sockets, for example, click smart Zigbee sockets. And when the home automation detects that we're no longer using that room, normally just because we hit a button to say we're not using it. Um, then it'll shut all those off and get rid of the phantom load. Um, but from the standpoint of like diverting directly and, you know, physically, if that's what you mean, I'm not, I'm not separating off physically the power that comes from the battery to, because I can't really, the only output is from the inverter, but conceptually sure. Yeah. When there's excess solar will turn certain things on, et cetera.

1:06:14I'm not really afraid of using the battery because a little bit in and a little bit out of the battery in the middle of its range. I don't think it's going to cause a lot of load on it. Maybe I'm wrong, but that's how it feels. So, um, so for example, if I have a hot water, I want to immersion heater, you can buy expensive and complicated systems that can vary the amount of power that goes into an immersion heater from anything from zero to 3000 Watts, for example, continuously vary them. But, you know, I could just duty cycle them on and off as well. I could just put it on for three seconds and then off the 10 and on to three and off the 10. Um, and I don't think that it's so little power for the inverter system, uh, and so little difference in net current through the battery. I don't think it cares. So I'm always looking for the way to do things as simply as possible.

1:06:55I get a little bit allergic to lots and lots of different companies, proprietary solutions, each of which costs, you know, at least a thousand pounds by the time you've had an electrician come and install it for you. And I don't mind investing good money, but sometimes things can be done in a simpler way. So, um, and again, I'm building it later at a time. You've caught me too early to tell you exactly how the control, uh, because I want it to just work on a basic level to start with. Um, and then when we find ourselves, for example, saying, Hey, we've got excess solar, let's turn on an immersion heater. Uh, I'm only going to do that two or three times before I get bored of it. And then I will find a solution to that, you know, and I'll start as simple as possible. And if I end up with something as complicated as a Eddie or whatever the other off the shelf solutions are, I'm fine. And I'll end up, you know, buying one of those, but I always like to assume that things are done in a more complicated way than they need to be and start, start afresh.

1:07:42That's just me being obstinate and refusing to, uh, to learn from others. That's good to know. Thank you. And thank you so much. Uh, also Ben for, uh, for contributing to, uh, the conversation through your experience. Um, a couple, a couple of learnings I had today, just from the motivation side of things. First being is, uh, actually installing, uh, you know, residential energy storage and solar could be an economic opportunity as well, because you could be selling back to the grid, which is something that I actually hadn't thought about before this podcast. Um, secondly, is, uh, Ben, you'd mentioned being the master of your own home. I think that's quite an attractive, uh, motivator. So, uh, yeah, and, uh, and Ben, for someone who wants to get started, for someone who has no clue what step number one should be, um, what are the, the different tips or approaches that you would, uh, you would, you would provide to the audience? And we'll start with you. Yeah. That's possible.

1:08:48Um, okay. Uh, okay. It's, it's, it's, uh, first thing you check, like, uh, um, are you first of the first question check? Are you satisfied with the electricity bill monthly? Uh, if you, if you are okay to, to bear it, uh, uh, maybe you can observe, uh, like, uh, uh, more people to, uh, uh, more users, uh, get more inputs of such products before, uh, really putting one into your home. This is, there'll be a number one recommendation. Um, the second, if you find like it, okay, my electrical, my e-bill, it's something really, I need to reduce control. Then, uh, you figure out, like, uh, you can have two ways. Uh, I think the basic way I suggested just try PV first, because like Ben mentioned, yes, it's really true. No matter how the country policies change, but the PV side is already able to reduce the e-bill. Somehow the payback years is one thing, but, uh, if you just check how the PV helps you monthly for the e-bill, uh, that's already one thing that you can, you can think about, it's what you're expecting.

1:10:01And, uh, if you are okay with the PV side, then I think that the timing, you can consider to add in, uh, this residential energy storage system. If you have an EV, uh, uh, together, then you can come, again, consider to have this storage system together with EV charger as a bundle solution to try, because, uh, that might give you, uh, uh, the latest experience, uh, uh, by using the solution in the market. So this is like, uh, uh, what I can think of like is three steps, uh, uh, the way to step into this product. Maybe I passed the back. You can also share our thoughts. Yeah, I would definitely second the EVs. I mean, remember the e, your app on general, your EV battery is maybe your battery EV 60 to a hundred kilowatt hours, right? Uh, that's huge for a house battery. So your EV battery and your EV energy demands could, your EV could easily double your domestic energy demands. That's one thing to note, um, depending on your mileage and your EV battery is probably going to be significantly bigger than your house battery in most cases.

1:11:06So thinking about your EV is really important. Can you charge it directly off solar in the day? Is that an option for you? Do you really want to be charging a big home battery? Uh, and then trying to charge the EV off that that's, that's not only inefficient, but it probably won't even have enough battery to charge your EV unless you've got a huge house battery. So thinking about the EV first is really good monitoring your power. So I'd want to know before I started, you know, what's my power history. Um, what's the history of the power, um, over time, you know, so that I can say, what's the peak power demands, uh, and what's the usage pattern. Uh, that that's really good idea. So if you're thinking about any of this stuff, getting a monitoring system of some sort, which by the way, can be as simple as just putting what's called a CT claim, a current monitoring clamp, current transformer clamp around a wire, it can be a DIY job to put some metering in place, or your existing smart meter might be enough, but knowing the power history is important and knowing how much of that power history included typical EV usage and how much didn't yet. And knowing how much of that power history included like modern other modern ideas, like air source or other heat pumps and how much didn't.

1:12:09So get a representative thing and watch out for gotchas, right? Deep pumps and cars, because that can change the figures dramatically. Um, yeah. And then you can size the system accordingly. And it doesn't, it doesn't have to be all in one go. You can start small. Uh, you could, and there's so many options, right? You can say, I only want to pay for cheap nighttime electricity. Well, that's one system. You can say, I want to be completely off grid. Well, you can work your way towards that. Um, you can say, I want to generate and sell. Um, that's possible. And all of the above at the same time, also possible if you have a sufficiently flexible, uh, system. So, yeah, but I would start by knowing what you're using and what you think you're going to be using in terms of future EVs and heat pumps. Uh, uh, yeah, to the group we spend, and I can add also some, I get two more things. I just, um, remember, like if, uh, you are living in a place that the power outage happens, uh, not that, okay, frankly, or at least, uh, happens, uh, uh, quarterly or several months based, you need to definitely consider battery storage system. You don't need to start from 10 kilowatt hour. You can start from, like, say 2.5, 2 kilowatt hour to 5 kilowatt hour system as a, as a try. Because this energy storage system, the basic, basic functions can help you store energy, even, either from PV or from power grid.

1:13:32We'll have this, uh, um, uh, grid power charge the battery. And during the outage stage, this power, battery storage can supply power to your emergency or urgent load, something you really need as emergency. So this is the basic function. And this is for the, uh, the suggestion for this, uh, users in that location, you definitely need this to consider, uh, this power outage period. And, uh, okay. And the, uh, the other thing I want to really want all the users to, um, be alert for such a product safety, um, because I'm working in this industry, I'm also a mom of two kids. So, uh, uh, I, I, I priority safety a lot. I mean, I think about my kids, the, this safety of such a residential, uh, uh, storage system is based on lithium-ion batteries. The safety size, uh, means like when you use the system, um, try not to put any, uh, flammable material surrounded and do not, uh, um, put it too close to, to, if you have case, let it out of the, uh, touch of your kids and, uh, don't get it to direct sunshine for the product or either, uh, direct the ring, uh, for, uh, I mean, rainfall the product at least give a shelter and, uh, uh, also make sure that, uh, uh, you can have this daily or very frequently, um, observing for such product and be alert once you smell some flavor or something. Sorry. I'm not trying to scare you guys away, but, uh, just like, see this, this product has lots of benefits. It's going to be the mainstream in the market for sure for all these users, but our safety, the safety part, it's still under development and for all, especially when you are using that for all the users that is already in this journey, be more alert. Uh, yeah.

1:15:40So that's the last thing I want to share. Thank you for sharing. And, uh, I think with this, we're pretty much, um, at the end of it for today. Um, I think that time flies by and I just want to have a big thank you to you and to share your insights with us on this really interesting topic of residential energy search systems and also everyone else for contributing or for Ben sharing your, um, you know, your hands-on experience. And it sounds like you're probably in the middle of it to continue. And maybe at some point you can come back and give us an update on how your system has been developing. And, um, yeah, but also everyone else for listening and contributing for today's session and especially often goes to my arm for ghosting again. And, um, yeah, with this, um, we are looking forward to our next session in a month time. So we always try to do them in the first side of the of the month. Um, so yeah, so the next one should be in the month time. We also got a range of different speakers and lined up. I think we have four or something and lined up, which is super exciting.

1:16:33But also if any of you are interested in speaking, please get in touch with us, um, either LinkedIn or any other platform and, um, it would be the light to hear from you as well and, you know, get you, get you on here and share your insights. But for today, I just want to thank you all and talk to you very soon. Bye bye. Thank you. Bye. Bye.