Benguela

Hi Temp, Thanks for helping me think this through. Part of the problem is that I don't know exactly what our roof construction is at the moment, except that it was re-done about 5 years ago by the previous owner. From the inside I can see the exposed rafters with plasterboard either above or in between them. The outside is pan tiles. In some rooms I know it is insulated plasterboard (because we've had to drill it for electrical work) but in other rooms I can see there is plain plasterboard, with some kind of foil-faced insulation above that. How can I figure out what we have exactly? Should I cut or drill into it from the inside to have a look? Or should I go onto the roof and lift a few tiles to have a look? I feel like, without knowing what the roof is at the moment, I also don't really know how to improve it.

Hi all, I live in a barn conversion with open rafters. What I have at the moment is some kind of foil backed insulation board between the rafters... with part of the rafter exposed towards the interior. Satisfactory in most of the house, but I have one tricky corner where two sections of roof meet that was never insulated and I now want to insulate it. I want to shove some semi rigid breathable insulation between those rafters. Maybe something like Hemspan, but I know there are alternatives made of wood wool. My thinking is it is easy to cut, easy to shape to size, and I can fit it with friction, no fixing needed. Question: once I've got the breathable insulation in between the rafters... how do I finish it? I guess I would ceiling board over the whole lot, but my question is do I have to leave an extra air gap once again between the ceiling board and the insulation? I was kind of thinking that the breathability of the insulation means that I don't need an air gap.

Hi Myatix! I'm also interested in getting the SMA Home Manager.... because I can integrate it with my Stiebel Eltron GSHP. 1. Is it any good? 2. What inverter do you have for your solar PV?

Hi Spacey73, Interesting! What inverter do you use with that Seplos battery?

Hi Figure 11, For those of us who are unhappy about what we're being paid for export: 1. Energy Local sets up local energy clubs allowing pv owners to sell their export locally. See here Welcome to Energy Local | Energy Local. But it's not cheap or easy. Needs £5k to start and needs an anchor partner who produces more than 30kW and has a three phase meter. 2. Support the Local Electricity Bill. The Community Energy Revolution — Power for People

Looks good!

Yes, just a typo, we've got a G99, all above board and legal.

Hi All, Got a SolarEdge based PV system (5000 HD Wave Inverter) this summer. Works a treat but can only be DC coupled with LG Chem or SolarEdge high voltage batteries. I'm a bit fed up spending money after going the 'premium' route with the SolarEdge stuff (and I'm not quite sure it was the right choice). So I'm wondering: What is the cheapest, simplest to fit AC coupled battery solution that I could scrounge from the ads on Facebook Marketplace? I see various Victron, Solis and Solax inverters on there for £300-£400 upwards. And I see Pylontech batteries for about £600 upwards. So surely it's feasible to: - start by getting the right inverter - wait for a good price on a Pylontech battery that someone is throwing out - get the whole system up and running - let it run for a season to see how it works - buy more Pylontech batteries if I like the setup and can find one at a good price. To show the depth of my ignorance, I'll admit that I basically don't know what inverter I need. Am I looking for an inverter/charger? Or an inverter and a separate charge controller? It looks like they're sometimes packaged in the same device and sometimes separate. And how would I end up controlling the whole setup? Presumably, an aftermarket AC coupled system isn't going to talk to my SolarEdge inverter, so I will need to tell the AC coupled battery system when to charge and when to supply. Any useful hints and tips about integration? I know very little, as you can see, so I'll get my friendly electrician to fit it at a day rate. But the whole thing must still be simple and foolproof enough that he doesn't puzzle over it, take days, go to Screwfix for some parts and then tell me that I bought all the wrong stuff. As it'll be fairly small scale, hopefully it won't affect the G98 that I've already got in place?

True... but if you're going for an AC coupled solution then you need yet another inverter. You'll have your SE inverter to turn your DC solar into AC for use in your house. And then you'll take that house AC and, using another inverter, invert it back to DC to store in your AC coupled battery. So why not just have one inverter from the start? Hence my advice to start with the inverter that you want and to build everything else around that.

Feed in tariff is gone. But you can get Smart Export Guarantee. Also, Octopus Outgoing tariff is very good at the moment. I've got a SolarEdge inverter and, it is as you say: if you install SE you are tied to using SE. My advice would be to start your planning around the inverter that you want. Find the right inverter first because that's the brains of your system. Then build everything else around that.

My jaw hit the floor! That's so much more reason why it's unfair that you can't be on Go and Outgoing at the same time. Take Joth's reasoning. If I'm on Outgoing and my neighbour is on Go, then the net effect on the grid is the same, right? One car gets charged and one PV system exports to the grid. So what is so wrong with house number 1 and house number 2 being the same place?

How many FIT installs there are compared to non-FIT installs is certainly relevant... but it is not the heart of the argument. Let me sharpen up the questions: Question 1: Do domestic PV owners who export excess energy on average get market value for the electricity they export. To work that out, we'll have to find out what is the average price paid for a unit of exported solar PV, taking into account all of the people getting FIT, what FIT rate those people are on (not all the FIT rates are wonderful) and all the people not getting FIT. Then we compare the average price to the wholesale market price or, if you like, to the ahead prices that other solar producers are getting. It is possible that PV owners are getting compensated just fine on average. But that will be mostly due to FIT pulling the average up. Us lot who only get SEG are getting between 1p and 4p. We are either 'idiots for missing the boat' or 'forced to sell at below market value' depending how you want to read the situation. The more interesting question to me is this one: Question 2: Are domestic PV exporters compensated for their excess energy on the wholesale electricity market... or is the rate for excess energy calculate outside the market. As I understand it, FIT payments come from the green levy... Am I right or wrong about that? So that's outside the market. Where do SEG payments come from? I think it comes from the electricity suppliers on the principle that the SEG scheme says 'you've got to have at least one SEG rate and that SEG rate has to be >0'. The electricity suppliers calculate SEG not by looking at how much the electricity is worth in the market, they just pay as little as possible. (Except obviously the Octopus Agile tariff that tries to create a little electricity market.) This leads on to the most interesting question of all for me: Question 3: What happens to the actual market value of all of the exported solar? Who gets that? Me and Radian worked it out and we call it £260million, but could be wrong.

Outgoing = 7.5p, Go = 7.5p, SEG = 4.1p According to their logic you can either have a cheap night time rate for your EV or a good rate for your solar excess, but not both. Here's what they write about it: Currently, you can't be on both Outgoing Octopus AND Octopus Go, our electricity consumption tariff designed for electric vehicle drivers. We've made this decision because both are such incredibly good value tariffs that it would be unsustainable for us as a business – the equivalent of letting people buying goods in a shop using a "3 for 2" offer and then bringing them back for a full price refund! The combination of Outgoing and Agile works really well and offers potential for great savings. You can choose to be on Octopus Go and join our new SEG tariff for Outgoing, offering 4.1p / kWh for your export – just get in touch with our team to take this option. https://octopus.energy/blog/outgoing/ They're basically saying 'this special offer cannot be used in conjunction with another special offer'. It strengthens my view that the electricity companies (or Octopus at least!) doesn't see SEG as a market rate that they are paying for a good that I provide. They see it as a loss leader.

Don't get me started on this issue. Octopus Outgoing is 7.5p. Octopus SEG is 4.1p. I'm on Octopus Go to charge my EV and Octopus won't allow you to be on the Go rate and the Outgoing rate at the same time. If you get Octopus Go, they will only allow you to go on the Octopus SEG rate. Their reasoning is 'we've already got your business, you're tied to us now, so we're not going to give you a good Outgoing rate'.

We're in a barn conversion complex. Not on mains sewage and have a shared sewage treatment plant between three barns. At the moment, my neighbour whose house is physically closest to the sewage system provides the electricity... It's on his supply, but it has a separate meter, so he pays for the electricity and then, once a year, reads how much the sewage plant has used and asks for a contribution from me and the other neighbour. I recently got PV and I think I can run the plant off my PV pretty much for free for six months of the year. I suppose we could run a new supply cable from my house to the sewage system and disconnect the old one, so that my house supplies the electricity. But isn't there a better way to do it without running a new supply? Could we somehow change the metering arrangement?

I yield to your research, Steamy Tea. Of the roughly 960k home solar installations in the UK, 268k look like they are entitled to FIT (27%) and my numbers above were clearly wrong. We can see how much people got paid through FIT at the table here https://www.ofgem.gov.uk/publications/feed-tariff-fit-tariff-table-1-april-2022 Column F shows all the different FIT rates between 2010 and 2019 and the tariffs were much higher in the earlier years and dropped as the years went by. In 2010 the highest tariff I see being offered for PV was "60.23". In 2019, the lowest tariff I see being offered for PV was "0.05". But is that figure in pounds or pence? I can't see directly. Either some lucky sod was being given £60 per KWh in 2010, or some poor mug was being stiffed with 0.05p per KWh in 2019. Or they changed from pence to pounds halfway through their own spreadsheet. 🤣 It doesn't matter as I'm just giving a rough picture. Still, my point is that not everyone who is on FIT is getting a great deal anyway and about 73% of PV owners having nothing better than SEG. I'm speculating, but I think the reason for that is that us PV owners are not treated as 'suppliers' on the grid. We are not being contracted to produce power (like the nuclear or gas or even big renewables suppliers). We just dump electricity on our local grids intermittently and are probably regarded as a form of background noise. We get a little pat on the head in form of SEG, but the amount of SEG isn't determined by market forces, the law says SEG must be >0p, so the electricity companies give us the least they can get away with and then the wholesale market just says 'thanks very much' and throttles down the gas peaker plants when the sun is shining. Anyone who understands the electricity market better, please correct me, but it looks like there is maybe 1,000GWh of electricity swirling around per year that the market doesn't pay for, or as Radian puts it above £260million. (Fag packet numbers, totally ready to be corrected.)

But I found there are There is actually a form of this already in Wales. See here https://energylocal.org.uk/ I don't totally understand how it works, but it looks like electricity users and small generators club together and then pool their production and use during half hour periods. Going to see if I can find out more and then maybe we can get one where I am.

Sure! We all know the game, we entered it and I'm not being all sour grapes. I like my system. It's just an interesting phenomenon: us Solar PV producers do our local grids a favour by magically dumping energy into it. No-one contracts us to do it (we're not contracted suppliers) and no-one bothers to pay us... much. So, seeing as there is about a million of us, isn't it rational to try to see if we can get a better deal. That's all. It's not Peterloo or anything.

Only doing some quick googling there, ProDave, and more than happy to acknowledge that the question 'how many UK homes with Solar PV do and do not get FIT?' is still open. But there's enough to be an interesting question, right?

We can start to guestimate by doing a quick google. If I get anything wrong, feel free to correct, I'm just doing this on a paper napkin. In 2020 there were 970,000 homes with solar panels in the UK (https://www.theecoexperts.co.uk/solar-panels/popularity-of-solar-power#:~:text=using solar panels.-,Residential,homes with solar panel installations.) and let's say the average installation is 4KW, producing maybe 3,000 KWh per year. So home solar produces about 2,910GWh? How much of that is exported... maybe a third or half? Of those 970,000 homes, 80,000 receive FIT. ( https://www.which.co.uk/reviews/feed-in-tariffs/article/feed-in-tariffs/what-was-the-feed-in-tariff-aAsa36S95iJy) People who got in at the beginning of FIT got a princely 50-something pence per kWh exported for 20-something years, but at the tail end of FIT it dropped to about 5p, I think. (In fairness, the capital outlay was considerable at the beginning.) Take away point: if there really are 970k homes with solar panels in the UK, only about 80k homes probably get more than 4 or 5p per kWh exported. The majority of us get the princely sum of £40/MWh that Steamy Tea quoted above. The day ahead wholesale price for electricity yesterday was £290/MWh. https://marketwatch.zenergi.co.uk/price/16-09-2022/ So collectively we are producing quite a bit and we are also selling our leccie to the grid quite cheap. Or, to put it another way, the market currently gives us few other options except to take a low price for it.

Not a totally fair comment... The easiest way to become a proper energy supplier is the Ofgem Licence Lite Route and that isn't pain free https://www.ofgem.gov.uk/sites/default/files/docs/2015/04/482_an_introduction_to_licence_lite_factsheet_web_0.pdf ... for one thing, you need to partner with a national energy supplier. The point of my hypothetical above wasn't to say I personally want to be the Gordon Gecko of energy markets... it was genuinely to check what people think about the Local Electricity Bill. For my part, I hope it could allow PV owners to club together as cooperatives so that, together, our coop could become a local electricity supplier giving us a little more bidding power in the market.

I'm a solar pv owner (6.6 kW of panels, 5kW inverter) and it sticks in my craw that I'm purchasing electricity at 30p/kWh and exporting excess energy to the grid at 4p/kWh (Octopus SEG tariff). I self-consume as much as I can by shifting use and charging my EV from solar and I'm also well aware that I can increase my self-consumption by getting a hot water diverter (£ 400) or a EV charger diverter (£800) or a home storage battery (£how-long-is-a-piece-of-string). But that requires me to spend more capital to increase my self-consumption rate. Why can't I just sell my electricity to my neighbour for 20p/kWh when I've got a bit of excess. Sun is shining, I plug in my EV and I tell my neighbour to quickly switch on her washing machine, to use up all my excess energy that I sell to her at a discount. Everyone is a winner: me, my neighbour and also the grid (because they don't have to generate energy using gas to allow my neighbour to do her washing... flattening the curve). It doesn't even have to be my direct neighbour... it can be anyone on the local grid who just happens to be switching on their washing machine right then. The more I think about it, it's not that I'm a mug who doesn't self-consume his excess electricity. It's that the market is set up wrong: for every kWh of electricity I produce, someone else pays 30p. And who grabs that money? The power distributor. They bill someone else 30p for electricity that I produce at 4p. And they don't add any extra value to that electricity... it's the same electricity, so their 26p profit comes not from some magic sauce they add to my electricity, it just comes from their position in the market vis a vis me. What's the answer for a more 'market-based' solution (rather than a home-engineering solution)? Should all us PV owners fight for something like the Local Electricity Bill? Info here: https://powerforpeople.org.uk/ Or is there any chance that the SEG market will ever begin to pay us more decent rates?

Does anyone know why SolarEdge single phase hybrid inverters are only compatible with high voltage batteries (StorEdge and LG Chem Resu)? The three phase SolarEdge hybrid inverters are also compatible with any 48V battery.

Pylontech has some newer generation batteries out. Most people probably know the 'U' series batteries, but there is also the slightly newer 'Force' series batteries. See e.g. here https://www.zerohomebills.com/product/pylontech-force-l2-7kw-lithium-solar-panel-battery-storage/ It looks to me like the Force series is internally the same as the 'U' series... but they come in a more attractive stackable housing. But then there is also the Pylontech 'Pelio' series. https://www.pv-magazine.com/2022/05/11/smarter-e-products-new-residential-battery-from-pylontech/ I can't find all that much info, but it seems Pelio isn't just a re-packaging of the U series... there's an (overlong, corny) launch video from China on Youtube that says energy density is 60% up from the Force (U-in-disguise) series. Anyone know more? I wonder when the Pelios will start hitting the UK market. Hope they keep on being good value.

Lots of activity on this thread lately with a few contributors adding StorEdge batteries to their SolarEge inverters. Has anyone gone down the other two routes that are available: 1. Getting an LG Chem Resu Prime battery... These are a lot smaller and lighter. (Also a bit cheaper) 2. Going for a cheaper AC-coupled solution.