Solar Panels UK - is it worth it?

[Js1977]

6kw max export - anything over you apply again. What is the kwp of your solar array?

I think you can set powerwalls to export limit and that is one of the few certified by DNOs - so would that mean you could add as much as you like as long as you define no more than 6kw goes out to the grid?

Just had the email from installer and yes he said another application would be needed. Grrr… at least it’s a start.

I do t know how it all works… for the moment the 3 panels will probably be limited by the enphase micro inverters which I believe is 290w per. I can only assume that it’s whatever potential the solar with micro inverters is able to export if maybe not governed by the powerwall/gateway

 

[ACarneiro]

summer - solar
autumn - solar and batteries to stretch out lower gen
winter - scrape the last photons off the roof and lean on off peak electric.

its a killer (but expensive) combo.

I know, I know.
My 4 Powerwalls made for a very smug all-day-on-low-rates winter

 

[Mrklaw]

Just had the email from installer and yes he said another application would be needed. Grrr… at least it’s a start.

I do t know how it all works… for the moment the 3 panels will probably be limited by the enphase micro inverters which I believe is 290w per. I can only assume that it’s whatever potential the solar with micro inverters is able to export if maybe not governed by the powerwall/gateway

three panels? How big each panel? Do you not have existing solar (perhaps fitting a few extra to get the batteries VAT free)? If only three total - like 1.2kw then you could put another 5-6kw up as long as the inverter and/or the powerwalls limit to 6kw output - you could do that without another application

 

[PITA]

I know, I know.
My 4 Powerwalls made for a very smug all-day-on-low-rates winter

With extended 6 hours on Intelligent Octopus... we'll be very smug all-day-low-rates Winter this year as well... on just two Powerwalls.

I've also applied for an additional 4 kWp array, South Facing. Which should help a lot .

 

[WannabeOwner]

I'm going to increase from 2xPW to 3xPW. I don't know if the man-maths would work - might well do with current prices, which weren't in my consideration way-back-when. But there are enough times in summer when I have excess sun today, and mediocre tomorrow (where I am using some off-peak top-up ... maybe even some Peak ... or not be able to PV-charge car enough for next trip and then car is charging Off Peak), and in Winter I rarely get through the day without some Peak usage

I have a question mark is around whether I put some PV on my West side [nearer to North West] (I have 2/3rds on East [a bit South of East], 1/3rd on South) to delay when PV goes off-line in the evening. I have enough kWh already, so would just be to stretch the PV-day ... if I could have interseasonal storage of some sort ...

 

[amnlinc]

Anyone here had any experience of SunSynk inverters and batteries ?

In the demise of Just4Solar we have an offer from Contact Solar that seems appealing price wise but replaces the GivEnergy Equipment with SunSynk, who I haven't heard of before. Their 5KW Hybrid Inverter seems to have a greater output on battery (the full 5KW).

We've had the sunsynk 8kw with pylontech batteries for a couple of months now. Started with inverter and batteries to take advantage of the cheap overnight rate and the panels were added last week. The inverter has been performing great and we have pushed it to the max 8kw output on several occasions. The app and data logging aren't as polished as the givenergy offering, it only logs a snapshot of data every 5 minutes so if that bothers you I would suggest using a Pi with Home assistant.

The output on battery would also depend on the discharge rating of your batteries. We currently have 2 5.12kwh pylontechs but max output solely on battery is around 4.8kwh at the moment as they are rated for 50% max discharge rate

 

[PITA]

I'm going to increase from 2xPW to 3xPW. I don't know if the man-maths would work - might well do with current prices, which weren't in my consideration way-back-when. But there are enough times in summer when I have excess sun today, and mediocre tomorrow (where I am using some off-peak top-up ... maybe even some Peak ... or not be able to PV-charge car enough for next trip and then car is charging Off Peak), and in Winter I rarely get through the day without some Peak usage

I have a question mark is around whether I put some PV on my West side [nearer to North West] (I have 2/3rds on East [a bit South of East], 1/3rd on South) to delay when PV goes off-line in the evening. I have enough kWh already, so would just be to stretch the PV-day ... if I could have interseasonal storage of some sort ...

I've held off buying a 3rd Powerwall, as we'll have plenty of storage with two electric cars.

The minute V2H becomes a thing, we'll use the Skoda Enyaq VRS battery which is 80 kWh.

That'll be a game changer.

 

[Dilly]

The last 1400 miles in our 2 EV’s, since the end of March, have cost zippo.
All done on freebie solar that I’ve been paid to produce under the FIT scheme.
the cars have done a total of 11,500 miles at a cost of £108.00
I love Spring and Summer

 

[Mrklaw]

The last 1400 miles in our 2 EV’s, since the end of March, have cost zippo.
All done on freebie solar that I’ve been paid to produce under the FIT scheme.
the cars have done a total of 11,500 miles at a cost of £108.00
I love Spring and Summer

come on, rub it in - you’ve been paid to drive. How much do you receive for that 1400 miles? you have FIT *and* presumably deemed export - lay it all out..

 

[Mrklaw]

I'm going to increase from 2xPW to 3xPW. I don't know if the man-maths would work - might well do with current prices, which weren't in my consideration way-back-when. But there are enough times in summer when I have excess sun today, and mediocre tomorrow (where I am using some off-peak top-up ... maybe even some Peak ... or not be able to PV-charge car enough for next trip and then car is charging Off Peak), and in Winter I rarely get through the day without some Peak usage

I have a question mark is around whether I put some PV on my West side [nearer to North West] (I have 2/3rds on East [a bit South of East], 1/3rd on South) to delay when PV goes off-line in the evening. I have enough kWh already, so would just be to stretch the PV-day ... if I could have interseasonal storage of some sort ...

if you have a lowish wall to avoid scaffolding, how much would you save on the VAT and can you get a net saving by putting token solar up?

possibly worth waiting to see if recent lobbying gets the government to make home storage batteries 0% VAT on their own?

 

[Js1977]

three panels? How big each panel? Do you not have existing solar (perhaps fitting a few extra to get the batteries VAT free)? If only three total - like 1.2kw then you could put another 5-6kw up as long as the inverter and/or the powerwalls limit to 6kw output - you could do that without another application

Yes. the 3 panels and inverters and battery came under (just) the price of the battery on its own by the time the VAT was taken off. How big or powerful the panels are does not matter in this case because the inverters are only 290w... The panels are 330w I believe so an oversize here towards the inverter is a good thing. I have plans to renovate a couple of outbuildings and currently raising another and this is where I plan to put the bulk of the panels which for the most part will get sun until the evening. I could accomplish the same on the house roof but would need more panels as it would be a split on both sides so for some of the day (at the moment up to about 3 pm and past 3pm ) one side would be doing "nothing". Arrays here will be irrelevant as each panels will have its own micro inverter hence for the extra cost I ideally want to get the most of all the panels for most of the day.

 

[WannabeOwner]

've held off buying a 3rd Powerwall, as we'll have plenty of storage with two electric cars.

The minute V2H becomes a thing, we'll use the Skoda Enyaq VRS battery which is 80 kWh.

That'll be a game changer.

Yes, that would definitely change my game too. I could dump far more kWh into the Cars than I am likely to choose to pay for static batteries, and V2H would keep the house going for a significant period of overcast days (barring mid winter). Our 2nd-EV usages is local-journeys, and although I enjoy having all the Tesla API stuff integrated, I might consider a non-Tesla 2nd EV if Tesla haven't done V2H by then.

if you have a lowish wall to avoid scaffolding, how much would you save on the VAT and can you get a net saving by putting token solar up?

Thanks. In this instance lady luck has shined on me. Installer has a client who has a PowerWall and A.N.Other brand battery for some other purpose and they have some-and-some integration issues and have decided to standardise on "Other", and I've said I'll take the PW off their hands - so basically 2nd price without VAT, then installation cost on top.

I'm really struggling with whether I want any more PV on West side. I have 48 panels East/South, its more than enough ... but if I could think of a better use for any excess I'd be happy to do it. Clearly my PV is going to be exporting same "Day Peak" as everyone else's so I don't see a future in having excess PV for a "better export tariff" at some future point, the only valuable export tariff will be from Battery as an alternative to Peaker Plants

However, I have contemplated whether I might fund a massive battery for the whole village. No idea if I want to bother to go down that rabbit hole though ... I expect a fair amount of herding-cats involved, and I don't have time & energy for persuading people when (assuming IF ) the figures tell the whole story, let alone persuading players who then get wobbly for whatever reason.

I'm pondering making an investment into some sort of energy store project. Maybe there is loads of big money in that sector already and no room for a small player? This Electrek article peeked my interest; admitedly its new-build, each house having PV and PowerWall, and collectively forming a micro-grid. I can't help thinking they would have been better off with a Megapack rather than individual PowerWalls, but I suppose PowerWalls-per-house is scalable, and makes it a "domestic" sized project rather than "commercial".

 

[ACarneiro]

Well, there are mutterings of flow batteries becoming a commercial “thing”.
Supposedly much cheaper and a lot more storage (but also larger, although that would be less of a problem in static batteries).

If something like Forever Energy ever become a viable product then things may become very interesting indeed.

 

[Dilly]

come on, rub it in - you’ve been paid to drive. How much do you receive for that 1400 miles? you have FIT *and* presumably deemed export - lay it all out..

Never fully done the sums before but it works out that the power used to charge the 4 EV’s we’ve owned since 2018 has earned £1170 in FIT & Export. In truth that’s like a Government statistic. I’d have earned that anyway

The last 1400 miles earned £81.

when I had my previous EV, an Ioniq Electric, I did once calculate that I was being paid about 2p per mile for driving it at the time

 

[Mrklaw]

today is the end of my octopus billing month. Had my solar+battery installed since 9th May so the first full month with it installed. Hoping for a good one but last couple of days has shown you need to be careful. Yesterday we ended the solar day around 5 due to the thunderstorms coming over and it being so dark, bit of AC nibbled the battery, and got to this morning with 23%. didn’t charge overnight as today’s forecast was 28kwh. But already my wife has put the tumble dryer on for two loads of bedding which has me down at 10% and its slowly charging. Hopefully will be ok but if its cloudy again that could be a long slog to charge the battery back up. And no AC allowed until its full

 

[WannabeOwner]

Hopefully will be ok

When cars have V2H that will take care of it ... huge buffer for the, reasonably rare, occasions when prediction has got it wrong

Hurry up Tesla!

 

[Pete UK]

today is the end of my octopus billing month. Had my solar+battery installed since 9th May so the first full month with it installed. Hoping for a good one but last couple of days has shown you need to be careful. Yesterday we ended the solar day around 5 due to the thunderstorms coming over and it being so dark, bit of AC nibbled the battery, and got to this morning with 23%. didn’t charge overnight as today’s forecast was 28kwh. But already my wife has put the tumble dryer on for two loads of bedding which has me down at 10% and its slowly charging. Hopefully will be ok but if its cloudy again that could be a long slog to charge the battery back up. And no AC allowed until its full

Nice.

I’m thinking like this as an example which applies in your situation….

Might be worth an “insurance” cheap overnight charge. Maybe ‘50%’ ? Or whatever you might lose in generation or need to get to the next days sun up/ cheap window again.
20kW overnight “insurance” buffer charge will cost £1.5 on IO.
If it’s cloudy/thundery you’ve covered yourself at 7.5p/ kW. If not it’s stored in the battery “bank” for later.
If you generate over what you need, and battery ‘overflows’ you can dump it all in the car or export it at 4p. So even if you have to dump all of the excess to export; those 7.5p/kW you end up exporting will only cost you 3.5p/kW as an insurance policy.
So a 20kW “insurance” cheap overnight charge would (worst case) cost you 70p for the day. Less if you export less. Or nothing if you dump it in the car.
However if you have to buy all those 20kW at 42p then it’s an £8.40 cost.

The cost benefit of having a bit extra in reserve (even if you have to export it ALL) is massively skewed to having a bit extra and having to dump it in the car or export it back rather than having to buy at 42p.

If you get it wrong by importing too much, say 8 times a month it’s negligible (or max of £5.60), if you get it wrong and are short that’s £67 !

I think this will come into play a lot more in the shoulder months. Thoughts?

In other news… hopefully my install is happening within the next couple of weeks.
Yay

 

[Mrklaw]

I only have a 9.5kwh battery so its needing a bit of management but lots more in the shoulder months. I had it set to 20% charge - on givenergy you have to set a charge window otherwise it'll drain completely. As it was, it didn't bottom out - 23% at the end of cheap rate and was slowly charging so I took the decision to allow the tumble drying before the house heated up too much, and based on the solar estimate looking ok for the rest of the day (and both cars full).

but yes in shoulder months I'll probably set a 50% figure as the solar gets a bit more variable, and I'll start shifting the cars to offpeak. Thats a couple of levers I have so far. Like you say worst case you're wasting cheap electric but thats better than needing peak electric.

I'm estimating around 25% gets me from midnight to 7am with a dishwasher and washing machine load and no off peak charging (so thats everything using the battery. I'd need to set a higher target % for the battery to make the appliances use off peak grid right now). and about 20% to get from end of solar to midnight. So about 50% from end of solar to next start of solar. Not too bad.

Also have my eye on another battery as soon as they decide hopefully to do 0% VAT I think I'll jump on an 8.2kwh which is better value per kwh than the 9.5 currently.

 

[Pete UK]

I only have a 9.5kwh battery so its needing a bit of management but lots more in the shoulder months. I had it set to 20% charge - on givenergy you have to set a charge window otherwise it'll drain completely. As it was, it didn't bottom out - 23% at the end of cheap rate and was slowly charging so I took the decision to allow the tumble drying before the house heated up too much, and based on the solar estimate looking ok for the rest of the day (and both cars full).

but yes in shoulder months I'll probably set a 50% figure as the solar gets a bit more variable, and I'll start shifting the cars to offpeak. Thats a couple of levers I have so far. Like you say worst case you're wasting cheap electric but thats better than needing peak electric.

I'm estimating around 25% gets me from midnight to 7am with a dishwasher and washing machine load and no off peak charging (so thats everything using the battery. I'd need to set a higher target % for the battery to make the appliances use off peak grid right now). and about 20% to get from end of solar to midnight. So about 50% from end of solar to next start of solar. Not too bad.

Also have my eye on another battery as soon as they decide hopefully to do 0% VAT I think I'll jump on an 8.2kwh which is better value per kwh than the 9.5 currently.

Yeah, that’s probably a good idea to get more battery. Think you’ll appreciate the extra savings at 7.5p/kW a lot in the autumn/ winter.

The 8.2kW GE battery, though cheaper, has an 80% DOD, so it’s effectively only 6.56kW usable in reality. Just bear that in mind. If it’s less than 69% of the price of the 9.5kW one then it’s cheaper per kW. If not, it obviously isn’t !

I guess this time of year it’s fairly easy to manage the solar set-up. Gets a bit more tricky outside of the summer months.

Glad it’s all working well for you though. Got any more data? I’m getting slightly obsessed with this now the closed install time gets. Haha. Like how much in total did your north array generate this month?

 

[Mrklaw]

8.2 states 100% Dod. Only the 5.2 and 2.6 say 80%? I'd double check though. Might go for the 9.5 just for symmetry

tricky as my octopus is 13th-12th for billing, and the givenergy/myenergi dashboards are calendar months so I don't have a full one yet. I can estimate from weekly.. hold on

last four weeks, most recent at top. The bottom entry is a bit odd I had an issue with the battery which needed resetting remotely so perhaps ignore that one