WEBVTT NOTE Transcript 2025-09-15 from FLAC by https://elvery.net/prototypes/transcribe/ on my MacBook Air M1 on maximum quality setting. NOTE Body significantly edited. 00:00.000 --> 00:09.000 Home Batteries --- And just to be clear, this is an electrical battery, so I have two sorts of batteries at home, I have a heat battery and I have electrical batteries. 00:09.000 --> 00:21.000 So, what and why? Why would you have home batteries? Well, you already have storage at home. You store your clothes, you store your food, you know, you wouldn't want to have none. 00:21.000 --> 00:33.000 We have a small house, but storage for all sorts of things you don't want to run out of tomorrow, or have to go somewhere expensive for, is good. You don't have to buy all your stuff in the corner shop because you forgot, so you do a bulk buy. 00:33.000 --> 00:39.000 Batteries can be useful because you can buy electricity when it's cheaper if you're on a variable rate, for example. 00:39.000 --> 00:52.000 So, and if you've got a water tank, for example, at home, hot water tank, you're already storing heat in there. And you have gadgets with batteries, you wouldn't have to want to walk around with this plugged in all the time. 00:52.000 --> 01:03.000 Who remembers having to have your laptop plugged in all the time to do anything? So, you can store electricity directly off-grid or from solar PV. 01:03.000 --> 01:13.000 So, it's possible ... I have solar on the roof and the most obvious reason to get a battery is because, surprisingly enough, I want to do things when the sun isn't up. 01:13.000 --> 01:18.000 So, you want to capture the solar off your roof and then use it even when the sun isn't up. 01:18.000 --> 01:31.000 But there's plenty --- Dan will tell you later about how he's got a huge battery so that he can fill it up during the winter and run his heat pump off it during the day --- whether or not the solar is doing anything. 01:31.000 --> 01:39.000 I have --- this exciting collection at the top --- I have a little off-grid system and these are things a bit like car batteries. 01:39.000 --> 01:46.000 And so, my website, if you ever go to my website, which you might for one of these things, that's entirely run off a Raspberry Pi off these things. 01:46.000 --> 01:51.000 They never touch the grid and I can charge my laptop and stuff off there. 01:51.000 --> 02:02.000 But I also have these AC-coupled batteries, and this is what you would probably be doing if you've got batteries attached. This is one brand Enphase, there are many others, 02:02.000 --> 02:08.000 which will absorb energy, for example, from PV and release it when you use it. 02:08.000 --> 02:13.000 And they try and stop energy flowing in or out of your house at all so you don't end up paying for it. 02:13.000 --> 02:26.000 But here's a heat battery, this is during assembly, under my combi as it then was, so I could fill this up with electricity overnight and our combi doesn't have to run for hot water. 02:26.000 --> 02:33.000 It's three different sorts of battery, but probably the sort we're thinking of when you're in here is this one --- the AC-coupled battery. 02:33.000 --> 02:47.000 So, why do we need batteries? Well, there's this little thing called climate change and renewables coming on and a change of that means that we can't do what we used to with electricity, 02:47.000 --> 02:51.000 which is turn up the generators when we want more electricity. 02:51.000 --> 02:59.000 And in particular, turning it up at peak rate when everyone gets back from school and wants their dinner. This is basically this peak, is people having their dinner in the evening. 02:59.000 --> 03:08.000 And so what we need is storage so we can fill up when the sun is shining or when the wind is blowing and release it later when we want to use it. 03:08.000 --> 03:17.000 And so using your own solar... So, in California they got to this problem where their demand used to be, and the second problem like this, the demand curves throughout the day.... 03:17.000 --> 03:23.000 This is midnight, coming through to midday, through to midnight again, used to be quite flat. 03:23.000 --> 03:29.000 But as more and more solar came on, the demand off the grid goes down lower and lower and lower. 03:29.000 --> 03:36.000 And then it has to recover really quickly to make up the evening peak when the sun's gone down, [and] people's air con is still running! 03:36.000 --> 03:40.000 And this is little thing called "ramp rate" is really difficult for the grid to deal with. 03:40.000 --> 03:47.000 You can't do a 0-60 in your coal [generation] plant, right? You need to take it gradually. 03:47.000 --> 03:53.000 So storage again helps "flatten the duck", as it's called, this is a duck shape, right? 03:53.000 --> 03:56.000 It's called flattening the duck. 03:56.000 --> 04:01.000 Will a battery save you money? Well, Dan believes it is saving you money, right? 04:01.000 --> 04:10.000 I think on the whole it's pretty marginal. But the grid is definitely, will need lots and lots and lots more storage and stuff. 04:10.000 --> 04:16.000 We can put behind our own meters so that we get charged less is also good. 04:16.000 --> 04:20.000 And I think, Alan, also you believe you've saved a reasonable amount from your... 04:20.000 --> 04:21.000 With a battery? Yes. 04:21.000 --> 04:29.000 Yes, because we're using it overnight. So in the winter months we charge the reduced rates. 04:29.000 --> 04:36.000 And again, so both Dan and Alan have time of day tariffs, so they get charged a different amount by the hour of the day. 04:36.000 --> 04:43.000 And they both have solar. So I don't have a time of day tariff, but I do have solar. 04:43.000 --> 04:48.000 So sometimes, usually, batteries with solar is a really good combination. 04:48.000 --> 04:54.000 Sometimes just batteries and a time of day tariff also works and may save you money. 04:54.000 --> 05:01.000 So just the point that came up earlier, there are two things about a battery that matter. 05:01.000 --> 05:08.000 One is kilowatts, which is the maximum power it can [supply]. When you flick on your kettle, that's three kilowatts typically. 05:08.000 --> 05:11.000 When you turn on your oven, it's two kilowatts. 05:11.000 --> 05:16.000 My batteries that I've shown you, they are slightly old now and [they're] an older design. 05:16.000 --> 05:20.000 So mine can only do just over a kilowatt of power. 05:20.000 --> 05:25.000 So if I turn on the kettle and the sun isn't shining, it will still bring two thirds of electricity in from the grid. 05:25.000 --> 05:33.000 But these days, you don't need to do that. So you should make sure you have a kilowatt rating, which is at least about three, which will cover an oven or a kettle or something. 05:33.000 --> 05:38.000 But the other thing is how much energy you store, and that's your kilowatt hours. 05:38.000 --> 05:48.000 And ... there isn't a perfect simple answer, but generally you should think about carrying about a day's use. 05:48.000 --> 05:54.000 For example, if you're on solar, you fill it up during the day off your solar and it discharges overnight. 05:54.000 --> 05:57.000 And then you don't need to import overnight. 05:57.000 --> 06:04.000 Now, if someone said to you, oh yes, let's have a big store of energy. Why don't we give you a big can of diesel and put it in your hallway? 06:04.000 --> 06:07.000 You would probably think, that's not such a great idea. 06:07.000 --> 06:16.000 So a battery, a battery actually stores less, much less energy per size and per weight than diesel by the can considerably less. 06:16.000 --> 06:20.000 But you wouldn't want in the can of diesel sitting in your hallway. 06:20.000 --> 06:29.000 So the rules have changed recently to make it clear that you shouldn't put batteries somewhere that might be an escape route like your hallway or somewhere, preferably not in the house at all. 06:29.000 --> 06:35.000 So Alan has a garage, you have a garage. I have a porch, so mine's going to have some of the porch. 06:35.000 --> 06:40.000 Garage. Right. So if you've got a garage, that's the best. 06:40.000 --> 06:43.000 Keeps the rain off them as well. It stops them getting frost. 06:43.000 --> 06:52.000 But otherwise, the porch ... Don't have them in the house on the whole. So I've got a friend who's in an attic apartment and wants to have one. 06:52.000 --> 06:59.000 And I'm suggesting not or at least keep it well away from the fire exits. 06:59.000 --> 07:09.000 So how much? So I'm suggesting with PV, you maybe want to go for a day so that ... this being Britain, we're not guaranteed solid sunshine for the whole of summer. 07:09.000 --> 07:13.000 So sometimes a little bit more so you can coast through some of the next day as well. 07:13.000 --> 07:22.000 Where where storage really helps is in the shoulder months, not the summer, not the winter, where you've got some rainy days and some sunny days. 07:22.000 --> 07:29.000 So something like a summer day's consumption is a good rule of thumb for PV, battery and PV. 07:29.000 --> 07:35.000 But if you want to do what Dan or Alan are doing, you get an off-peak rate. 07:35.000 --> 07:45.000 You fill up the thing overnight on cheap electricity and you run your house off it, unless you know it's going to be sunny, in which case you leave space for the solar to fill it up for you. 07:45.000 --> 07:49.000 You can save quite a useful amount of money. And this is what the grid is going to need to do anyway. 07:49.000 --> 07:55.000 So you're helping save the planet, in which case you should be covering not a summer day's consumption. 07:55.000 --> 08:02.000 You should be covering at least a winter's day consumption. If that's including your heat pump, that's going to be a lot more. 08:02.000 --> 08:08.000 So for us [a] summer day's consumption is about five or six kilowatt hours, excluding any heating stuff. 08:08.000 --> 08:14.000 Winter: I can't actually remember, maybe 15, so three times more for us.