Just for fun, here is a "solar calculator". You stick in some basic info, find your property on a map, and bingo, it tells you stuff.
It tells you the two key things - an estimated installation cost, and an estimated annual saving. It doesn't, mysteriously, tell you the therefore expected payback, so you have to divide one by the other yourself.
In my case, (I chose a 6KW install), it suggests:
Installation cost:£7,913
Annual saving:£626
So therefore payback of 12.6 years.
All a load of nonsense no doubt, but be interesting to see the figures for others around the country, if anyone wants to try?
www.pvfitcalculator.energysavingtrust.org.uk/
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Quickly ran my details through it and I think it is giving a fair representation, compared to my own installation.
I think my actual annual ££ saving is higher, and my (old tech) panels appear not to have degraded much, as this year is my best ever (out of 10).
I have had to have a new inverter already (though I managed to get it nearer £500 than £700, but that was in the past!!) so their allowance for lifetime maintenance is probably about right.
I'd never calculated by CO2 saving but quite happy with the figure they've given.
A lot depends on the orientation and shading - I'm lucky, facing almost due south with no shading - but if you have significant shading even only affecting part of the array you'd need to make sure they used microinverters one each panel to avoid while string being killed by it.
It's better if you can have S facing but if your house is E/W then panels on either side would catch the morning and evening sun better than south does.
Just out of interest, my modest system is 2.73kW and generates between about 2000 - 2500 kW per year. It cost me £10500 in late 2011 and, being on on of the old but slightly less generous FIT arrangements, I got my money back by 2019. The payments are guaranteed for 25 years and at the moment my total income is about £1.5k a year, tax free. So maybe overall not a great ROI but I'm happy.
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Interesting.
Its suggesting 2800 kWH output for my 4KW system whereas Ive returned just over 3000kWHk ish, so I suppose its not far out.
I've not been anal over recording output and returns but only yesterday received a payment of £941 for 1510 kWH generated between 20/5/22 and 26/8/22. I cant find the email bit believe the previous quarter was over £600.
We bought in at the height 13 years ago and benefit from the high tariffs and paid £14K for the instillation (supposedly better panels) It has however been an exceptional summer so the returns have been very good.
As a matter of interest is there anything physical that lets you know your inverter has gone belly up other than the lack of recording output.
Last edited by: Fullchat on Fri 2 Sep 22 at 12:05
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I put a 2kw system in (not sure how many panels that works to?)
Install 3971
Maint costs 1450
Benefit 299/year.
Quite a long payback then.
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No, even anal me didn't realise for a few days. I'd managed to hook up the old inverter to my PC but didn't spot that no readings were coming down.
The new inverter has an app telling me what it's up to but I don't check it regularly. But I do note down the reading from emails every so often.
The initial inverter went at about 4 years old, warranty was 5 years yet it took 2 (summer!!) months to replace. Then the replacement went in 2020 and I found a local guy and it was done within three weeks. The fault code was the same both times so I suspect it was a weak point (in fact I found a number of instances on the internet of others with similar).
Finding a reputable contractor is, as always, difficult. Most of the early solar companies are long gone (probably along with the warranty that their work came with).
I suppose the other consideration if you are considering it is adding some batteries. AIUI the inverter is different and I wish I'd gone for the (slightly more expensive) battery one for futureproofing. Then you can save your excess generation for use in the evening (and if the cheaper overnight rates are still there to be had, top up your batteries overnight).
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Very late in what has been an exceptional season but we have a traditional hot water tank and immersion.
Have been looking at the diverters that automatically channel surplus output to the immersion instead of the grid.
There seems to be a lack of availability of products (looking for wireless) until November.
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I didn't have an immersion till a forced cylinder replacement at the start of the summer.
I then put in an iBoost. It has been quite effective in that we've only put the hot water on about once a week or less but it cost £320 and it will take a long long time to get my money back. Probably wasn't really worth it but my gas was actually £65 cheaper over the same period but that isn't solely due to the diverter. I don't have so much spare power as many would, being a smaller system.
The single best thing I have done this year is replaced the old freezer (documented elsewhere). I will re-work out the savings but I am using about half of the overnight power I used to.
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We're on oil.
The iBoost is on my list along with Solic which are cheaper but require a dedicated feed from the consumer unit to the immersion which is a bit of a faff here.
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I checked out here, west facing, and the new build, south east facing. The figues were almost identical.
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Solar calculator for fun and profit - smokie
