Solar opinions/experiences
Discussion
Any of you here got solar panels and battery storage? We’re considering it and have been quoted around 12k for panels and an 8kw battery storage.
Our house faces directly South and with garage and extension we can have panels facing East and West as well as South to fully benefit form the Sun.
Chap reckons around £60 a month pay back to the grid as well based on our usage though I’d need to do the sums to confirm.
Most of our elec usage is evenings so battery storage is a must to fully benefit.
I’m just debating if it’s worth doing – we’ll be in this house the next 10 to 15 years so would certainly be long term. Initial calcs we should be paid back from savings and selling excess back within 7-8 years.
Our house faces directly South and with garage and extension we can have panels facing East and West as well as South to fully benefit form the Sun.
Chap reckons around £60 a month pay back to the grid as well based on our usage though I’d need to do the sums to confirm.
Most of our elec usage is evenings so battery storage is a must to fully benefit.
I’m just debating if it’s worth doing – we’ll be in this house the next 10 to 15 years so would certainly be long term. Initial calcs we should be paid back from savings and selling excess back within 7-8 years.
First off read the other thread about solar panels. https://www.pistonheads.com/gassing/topic.asp?h=0&... If its a 4kw system facing south it will likely produce around 4000 kwh a year. so about 11 kwh a day. This is based on my 4kw system facing south for the last 12 years. In January you will likely make very little at all.
There is another long running solar thread on here that maybe worth a browse.
For ref, we have one 9 year old 3.6kW system (typical max size for export limit) on a south facing roof that until recently was also supplying the household loads but without a battery. Our annual production is around 3-3.5 MWh, so worth only about £450 at an export rate of 15p/ KWh, assuming all the generated electricity were to be exported.
You will likely benefit more financially from having the battery to allow you to reduce peak electricity import costs by capturing PV energy in the summer and time shifting your import in the winter to use cheaper off peak electricity.
For ref, we have one 9 year old 3.6kW system (typical max size for export limit) on a south facing roof that until recently was also supplying the household loads but without a battery. Our annual production is around 3-3.5 MWh, so worth only about £450 at an export rate of 15p/ KWh, assuming all the generated electricity were to be exported.
You will likely benefit more financially from having the battery to allow you to reduce peak electricity import costs by capturing PV energy in the summer and time shifting your import in the winter to use cheaper off peak electricity.
Everybody's use pattern is different.
You can look at what panels typically deliver, and work out how that can save you money.
That really need s to be done for good/bad days/weeks for each month of the year.
Then you need to realise that future prices might be very different.
£12k is a lot of money. To us, it's more than 12 years electricity bill.
Some people have paid much less?
I think battery systems are still getting cheaper?
Last time I did the sums for my own case, I decided I'd only bother if I needed a new roof anyway, or could get a 4kW system for under about £4k.
You can look at what panels typically deliver, and work out how that can save you money.
That really need s to be done for good/bad days/weeks for each month of the year.
Then you need to realise that future prices might be very different.
£12k is a lot of money. To us, it's more than 12 years electricity bill.
Some people have paid much less?
I think battery systems are still getting cheaper?
Last time I did the sums for my own case, I decided I'd only bother if I needed a new roof anyway, or could get a 4kW system for under about £4k.
Got ours last Dec, see if there is a Council/Solar together scheme in your area.
Octopus quoted £10.2K for 5Kw panels, 5Kw battery and invertor, Solar together was £5700.
Things to note. Look at your usage carefully and work out how much you really use and at what time. We have 5kw batteries which now in longer days we can run the house on overnight until the morning, but we still need a couple of hours of import first thing in the morning. We have very low usage. I'd like more battery but cant justify the additional cost.
If you've cheap overnight power, then in winter you could charge the batteries to offset import costs.
On a sunny day, best I've seen is around 27kWh generation a day, last month was 604kWh, Jan was 146kWh, Feb was 178kWh.
Octopus give 15p per kWh export, really you need to be using as much of your generation as possible to offset the 24p import charge, so washing machine, dishwasher, oven cooking etc.
Octopus quoted £10.2K for 5Kw panels, 5Kw battery and invertor, Solar together was £5700.
Things to note. Look at your usage carefully and work out how much you really use and at what time. We have 5kw batteries which now in longer days we can run the house on overnight until the morning, but we still need a couple of hours of import first thing in the morning. We have very low usage. I'd like more battery but cant justify the additional cost.
If you've cheap overnight power, then in winter you could charge the batteries to offset import costs.
On a sunny day, best I've seen is around 27kWh generation a day, last month was 604kWh, Jan was 146kWh, Feb was 178kWh.
Octopus give 15p per kWh export, really you need to be using as much of your generation as possible to offset the 24p import charge, so washing machine, dishwasher, oven cooking etc.
We have a similar setup, but I bought it primarily to act as a home backup in the event of power outages which have been becoming more frequent round here. So for me the cost was set against the various things that seemed to be going on the fritz with the mains sagging and surging.
As others have said, you are probably not going to see a particularly quick payback. There are cheaper battery suppliers (e.g. Fogstar) which may be worth looking at since most of the saving is probably going to come from time-shifting energy usage rather than the solar generation. But I think in most cases payback arrives roughly at the same time the battery warranty expires ... at least when I was looking that seemed to be the case!
As others have said, you are probably not going to see a particularly quick payback. There are cheaper battery suppliers (e.g. Fogstar) which may be worth looking at since most of the saving is probably going to come from time-shifting energy usage rather than the solar generation. But I think in most cases payback arrives roughly at the same time the battery warranty expires ... at least when I was looking that seemed to be the case!
I paid £8K for 4.3kW panels and GivEnergy 8.2kWh storage, but that was in 2021 and we are in the South West.
The system has been excellent, very happy with it. Last month I exported £68 worth and imported £25 worth so net gain of about £43. Import mainly for my EV and charging the battery off-peak. However April this year was unusually sunny.
The system has been excellent, very happy with it. Last month I exported £68 worth and imported £25 worth so net gain of about £43. Import mainly for my EV and charging the battery off-peak. However April this year was unusually sunny.
119 said:
Sure I read that the batteries have to be positioned outside?
Not specifically, however there are recently updated guidelines to outlaw some internal locations like loft spaces. Also requirement for nearby smoke alarm if mounted inside a house etc. Outside wall or in a garage generally a better location if you can do it.Road2Ruin said:
No chance you will get £60pm export. More likely £40pm, in the summer and nothing in the winter. My total last year, was £240 ish, from a 4.4kwp split system.
4kW system should produce about 4,000 kWh per year. At 15p/kWh, that's about £50 a month average, if you export it all.Road2Ruin said:
No chance you will get £60pm export. More likely £40pm, in the summer and nothing in the winter. My total last year, was £240 ish, from a 4.4kwp split system.
Our system has only been live a couple of months, but April export was 85 quid. I appreciate the weather was good for April, but it's encouraging. 5kw system and 5kw battery. Fitted by Octopus at 10k. We are currently making more in export than gas and electric cost combined (only just, admittedly). There's only 2 of us, so not heavy users, but if cost allowed, a bigger battery would be better for a bigger household especially with the cheap overnight charging.Edit following re read of thread - battery is in the garage, Octopus fitted linked smoke alarms to house and garage.
Edited by Essel on Saturday 10th May 10:46
Number 1, figure out your daily electricity consumption, don't forget to include a dishwasher cycle, oven for however long you use it most days and washing machine if it's a lot (kids make it nearly a daily thing).
Number 2, take 2/3's of that figure in KW and that's about your battery size - you can take a risk and go lower if your panels are south facing and liable to generate more in the spring and autumn - for example mine are south-east so even in the summer generation is over by about 5:30/6pm when South face panels might generate a little more over the day.
Number 3, Figure out how many panels it would take to charge that battery in early spring and late autumn. This does depend on which direction they are facing, south east gets you morning solar power so your battery only needs to get you to about 7am even at this time of year, south west would only get you power from perhaps midday but to much later in the day.
Number 4, get yourself on a load shifting contract so that in winter/no sun conditions you can charge the battery cheaply overnight.
Number 5, check the battery specs (read Byker's issues about battery charging limitations against temperature), solar panel specs, warranty length, get a demo of how easy it easy to control and force overnight charging or daytime discharging.
Number 6, give up on the idea of making a ton of money from the network by selling back - as with all gambling, the house always wins. Look instead to maximise your solar gain to your house, game the overnight charging when you know it'll be overcast or not sunny the next day, and be prepared change your routines so that you are happy to do stuff like leave the dishwasher until the following day if its going to be sunny, or dishwasher overnight on a cheap rate if it won't be sunny, get the washing machine and tumble dryer on when it's sunny - I even put portable AC units on the summer instead of thinking about selling back to the grid.
Number 2, take 2/3's of that figure in KW and that's about your battery size - you can take a risk and go lower if your panels are south facing and liable to generate more in the spring and autumn - for example mine are south-east so even in the summer generation is over by about 5:30/6pm when South face panels might generate a little more over the day.
Number 3, Figure out how many panels it would take to charge that battery in early spring and late autumn. This does depend on which direction they are facing, south east gets you morning solar power so your battery only needs to get you to about 7am even at this time of year, south west would only get you power from perhaps midday but to much later in the day.
Number 4, get yourself on a load shifting contract so that in winter/no sun conditions you can charge the battery cheaply overnight.
Number 5, check the battery specs (read Byker's issues about battery charging limitations against temperature), solar panel specs, warranty length, get a demo of how easy it easy to control and force overnight charging or daytime discharging.
Number 6, give up on the idea of making a ton of money from the network by selling back - as with all gambling, the house always wins. Look instead to maximise your solar gain to your house, game the overnight charging when you know it'll be overcast or not sunny the next day, and be prepared change your routines so that you are happy to do stuff like leave the dishwasher until the following day if its going to be sunny, or dishwasher overnight on a cheap rate if it won't be sunny, get the washing machine and tumble dryer on when it's sunny - I even put portable AC units on the summer instead of thinking about selling back to the grid.
OutInTheShed said:
Road2Ruin said:
No chance you will get £60pm export. More likely £40pm, in the summer and nothing in the winter. My total last year, was £240 ish, from a 4.4kwp split system.
4kW system should produce about 4,000 kWh per year. At 15p/kWh, that's about £50 a month average, if you export it all.Road2Ruin said:
Ours is split SE and SSE, so jot going to get anywhere near those figures. Exporting it all, too, is a pipe dream. We have a battery that I fill every night at 6.7ppkwh and still use solar during the day. Our average cost per kwh, though, is around 8ppkwh. So quite happy.
Exporting it all is a baseline, if you take the battery away, you either export or save import.Typically export is 15p, import is >25p. So 'export all' is the worst case, until tariffs change.
Actually some people get excited about heating water they don't need or running the dishwasher every time the sun comes out, they are heading to the third option of 'wasting power'. While wearing out appliances and using more water.
If you add a battery you get complicated and have to compare solar + battery with just battery.
You can probably make a case for just having a battery being more cost effective than solar.
So it's quickly quite personal with your own use case and tariff predictions into the next 5/10 years.
If you are split over two roof directions, you can get more panels but limit peak export and/or peak generation and get a longer period of generation.
As soon as we move on from the simple case of 4kW of panels on a S facing roof, there are a lot of variables!
Even then, not every house gets the same quota of sunshine.
I came close to installing solar panels but didn’t, fortunately. The cost via the council’s Solar Together scheme wasn’t that great in retrospect. It just meant I would have got a system installed whereas at that time all the smaller tradesmen didn’t even respond to my query.
With interest rates having risen the return doesn’t compare well with the money sitting in a savings account. If you want a system with a battery to be independent of the grid and resilient against power cuts, then fair enough, go ahead. But as a money-saving or money-generating machine I don’t see that panels on their own cost in at all given current rates paid when selling to the grid. The up-front cost of the panels and battery would have to drop a lot more for that to happen. The only scenario where I think you might save money is buying power on a cheap tariff overnight and store in a battery for use in the day.
With interest rates having risen the return doesn’t compare well with the money sitting in a savings account. If you want a system with a battery to be independent of the grid and resilient against power cuts, then fair enough, go ahead. But as a money-saving or money-generating machine I don’t see that panels on their own cost in at all given current rates paid when selling to the grid. The up-front cost of the panels and battery would have to drop a lot more for that to happen. The only scenario where I think you might save money is buying power on a cheap tariff overnight and store in a battery for use in the day.
southerndriver said:
I came close to installing solar panels but didn’t, fortunately. The cost via the council’s Solar Together scheme wasn’t that great in retrospect. It just meant I would have got a system installed whereas at that time all the smaller tradesmen didn’t even respond to my query.
With interest rates having risen the return doesn’t compare well with the money sitting in a savings account. If you want a system with a battery to be independent of the grid and resilient against power cuts, then fair enough, go ahead. But as a money-saving or money-generating machine I don’t see that panels on their own cost in at all given current rates paid when selling to the grid. The up-front cost of the panels and battery would have to drop a lot more for that to happen. The only scenario where I think you might save money is buying power on a cheap tariff overnight and store in a battery for use in the day.
A lot of that depends on various things like you tax rate for savings, inflation rate etc.With interest rates having risen the return doesn’t compare well with the money sitting in a savings account. If you want a system with a battery to be independent of the grid and resilient against power cuts, then fair enough, go ahead. But as a money-saving or money-generating machine I don’t see that panels on their own cost in at all given current rates paid when selling to the grid. The up-front cost of the panels and battery would have to drop a lot more for that to happen. The only scenario where I think you might save money is buying power on a cheap tariff overnight and store in a battery for use in the day.
If you are 40% tax rate, interest 5% instant access, that's 3% net against 2.5% inflation.
The flip side of this argument is that prices of panels etc have not been inflating, they have been getting cheaper.
I've saved more by waiting for panels to get cheaper than I'd have saved on electricity.
People were paying £12k for what you can now get for £5k just a couple of years ago.
Where's the bottom of this curve?
But as they say, past performance is not always a guide etc..
I don't trust anyone's prediction of interest rates and inflation any more than I trust their prediction of electricity tariffs.
I think a proper analysis would include costs for maintenance over 25 years and writing off the panels over that period, and other components over other periods. There are also subtle costs, like batteries and inverters taking up garage space!
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