Solar power. Is it worth it?

[Mottie]

As above. Just had this through the door from Sad Khant.

 

[JohnW2]

As for the title of this thread, for what it's worth, my personal short answer would probably be "No" (in the UK).

Kind Regards, John

 

[DiyNutJob]

Your part of london has much sun? With it being on the roof, how much is the cleaning cost?

With my small car battery panel, it's not much good for 4-5 months of the year.

 

[SimonH2]

And the key thing here - it's a reverse auction so that means whoever will do the job the cheapest, and we know that cheapest generally means "is prepared to cut the most corners".

 

[JohnD]

without knowing what it costs, you can't tell.

I already have solar panels, and when I looked at the cost of adding a batt, it was not economically viable. Figures below.

IIRC it was about £6k at the time.

To be of use to me, I would want to store 6kWh, which is enough to run the tumble drier for free on a day that is not sunny, or on a day that was sunny earlier, then cloudy. As it is, laundry days are usually planned to take advantage of sunshine. So I already save in sunny spells, without needing a battery.

my overnight use is about 300w in summer, so if I could store 3kWh then, in summer, I could cut about 3kWh from my daily usage if the preceding day had been reasonably sunny (saving, what? 50p a day for the 6 months of the year? On the days that are fairly sunny ? Around half of them?)

Winter generation is negligible.

You get around 6 sunny months a year.



This march I generated an average of 5.5kWh per day, which is above average. Not much of it was exported because fridge freezers, PC, lights, stuff on standby gives a background load of 300W to 500W for 24 hours a day. Appliances are extra.

Last July I generated an average of 13.4kWh/day and probably exported most of it. I couldn't use it all because it is more than my usage.

If I had used it all, via a battery or otherwise, it would have saved me around £2 a day. How many £2 days are there in £6,000? There are 3,000 sunny summer days. Maybe 20 years?

If I had invested £6,000 (gross) in my managed pension 10 years ago it would be worth £14,100 today.
I don't have a 20 year figure, but it would be more.

A much better investment than buying a battery, even without the tax and NI advantages.

 

[oldbutnotdead]

without knowing what it costs, you can't tell.

I already have solar panels, and when I looked at the cost of adding a batt, it was not economically viable. Figures below.

IIRC it was about £6k at the time.

To be of use to me, I would want to store 6kWh, which is enough to run the tumble drier for free on a day that is not sunny, or on a day that was sunny earlier, then cloudy. As it is, laundry days are usually planned to take advantage of sunshine. So I already save in sunny spells, without needing a battery.

my overnight use is about 300w in summer, so if I could store 3kWh then, in summer, I could cut about 3kWh from my daily usage if the preceding day had been reasonably sunny (saving, what? 50p a day for the 6 months of the year? On the days that are fairly sunny ? Around half of them?)

Winter generation is negligible.

You get around 6 sunny months a year.



This march I generated an average of 5.5kWh per day, which is above average. Not much of it was exported because fridge freezers, PC, lights, stuff on standby gives a background load of 300W to 500W for 24 hours a day. Appliances are extra.

Last July I generated an average of 13.4kWh/day and probably exported most of it. I couldn't use it all because it is more than my usage.

If I had used it all, via a battery or otherwise, it would have saved me around £2 a day. How many £2 days are there in £6,000? There are 3,000 sunny summer days. Maybe 20 years?

If I had invested £6,000 (gross) in my managed pension 10 years ago it would be worth £14,100 today.
I don't have a 20 year figure, but it would be more.

A much better investment than buying a battery, even without the tax and NI advantages.

I really need to do some more sums. 'Free' electricity looks so tempting but it isn't actually free is it.....

 

[JohnW2]

I really need to do some more sums. 'Free' electricity looks so tempting but it isn't actually free is it.....

Indeed. A lot of the oldadages/proverbs have got more than a fiar bit of truth in them- so there is very rarely such a thing as a "free lunch/dinner", and most things which sound "too good to be true" usually are!

It's rather like the environmental benefits of re-cycling (which may seem 'obvious' until one starts thinking)- which will often/usually be cancelled, if not reversed, if one makes a 'dedicated' trip to a recycling centre using a petrol/diesel-fuelled vehicle. Even some of the recycling processes themselves are of questionable (or, at least, marginal) net environmental benefit.

Returning to context, one of the reasons why the sums about domestic solar generation are so potentially misleading is that (as sort-of implied by JohnD) , even if they are realistic, in terms of amount of sun etc. (which they very often aren't), they look at potential financial benefits over a very long period of time without considering 'cashflow'. Since the capital outlay is considerable, for at least the first few years one will inevitably be financially 'worse off' than would have been without the PV. Only after many years might one start seeing financial benefits but, depending upon one's age and circumstances, one might then not even 'still be around'!

Kind Regards, John

 

[joe384]

Returning to context, one of the reasons why the sums about domestic solar generation are so potentially misleading is that (as sort-of implied by JohnD) , even if they are realistic, in terms of amount of sun etc. (which they very often aren't), they look at potential financial benefits over a very long period of time without considering 'cashflow'. Since the capital outlay is considerable, for at least the first few years one will inevitably be financially 'worse off' than would have been without the PV. Only after many years might one start seeing financial benefits but, depending upon one's age and circumstances, one might then not even 'still be around'!

Or you might have moved house! Although I suppose you could argue solar panels might add to the sale price.

The other factor is that even if you do all the Math, there are so many unknowns - Will the unit price of electricity go up even more massively over the next few years? Will petrol prices go insane meaning that having an electric car being charged by your solar panels makes a lot of sense?

 

[ericmark]

It is an unknown, now there is no government incentive or guarantee on pay back, it is down to if the panels work as advertised, I think with a south facing accessible roof they are likely good, but the amount of wood burners local to me, cleaning is clearly some thing which needs considering. Even my own wood burner, although I have never used it, I may in the future so could result in tars adhering to the panels.

To build an estate of houses with solar panels and accessible roof for maintenance would clearly be a good idea, but price of scaffold to work on roof at moment exceeds the annual fuel oil bill, plus my roof is east/west, which was the best selection when the house was built as wind tends to go up or down the valley.

The whole save the planet thing seems to be how to make money, it is clearly better to electrify trains to doing cars and wagons, so why do we still have so many lines still not electrified? Adverts showing some one clapping to turn lights on/off after fitting a smart meter just points out the government is clearly lying, so I don't believe anything the government says.

 

[DiyNutJob]

Personally, I think it's extremely irresponsible for the government to be pedalling this for the UK where it is renowned for its rain.

 

[JohnW2]

Or you might have moved house! Although I suppose you could argue solar panels might add to the sale price.

That's really what I meant by "not still around" - not 'still around' the propoerty in question, although maybe still alive, somewhere However, it may also subtract from the sale price. It really all depends upon the buyer

The other factor is that even if you do all the Math, there are so many unknowns - Will the unit price of electricity go up even more massively over the next few years? Will petrol prices go insane meaning that having an electric car being charged by your solar panels makes a lot of sense?

There will always be massive unknowns, hence 'gambles', given that fuel prices can (and sometimes do) change dramatically almost 'overnight'. One can but do the maths on the basis of one's best attempt to predict what the future will hold.

Common sense might suggest that, if solar power is a reasonably viable option in a particular country (in terms of climate etc.), to have millions of (domestic etc.) micro-installations doing it is very unlikley to be the most efficient method of making use of what solar energy is available - just as it would probably make no sense to have every house generating its own electricity from fossil fuels or even nuclear reactors It's probably a situation in which "big is beautiful", despite the distraction losses/'costs' (in the broadest sense) when generation is centralised.

Kind Regards, John

 

[ericmark]

Maybe my thoughts on solar power have been influenced by what happened to my father-in-law.

OK these were DHW panels not electric, which to be fair daughter has in Turkey and they work well in Turkey. But in North Wales the result was very different.

After they were fitted we asked my FIL how they were going, and he reported a massive reduction in his electric bill, and we all thought they were working well until he had a smart meter fitted.

At this point he reported no DHW, so on investigation we found after turning off the gas, the installer has not re-lit the pilot flame on the boiler, however this was hight of summer, so should not need the boiler, found the pumps for the panels were labelled immersion heater, so FIL had turned it off as no longer had an immersion heater.

Turning it back on and water still did not heat up, so thought maybe over heated due to power being turned off, so got an installer to recommission the system, ensuring no air etc. Still no hot water from solar panels, FIL died, house sold, and panels left on roof, but all the pumps and tanks removed by new owner.

The main point is my FIL was convinced the panels were working and saving him money, where in reality he had moved from electric to gas water heating, and was getting no solar energy.

When some one pays for solar panels or an electric car, or any other new fanged appliance, it takes a lot of guts to say I was conned and it is no good really.

I know the local milkman where I use to live bought a Renault Kango long wheel base electric van for his milk round, he said yes it did save him money, electric was cheaper than diesel. But it had a claimed range of 110 miles, his milk round a fixed 64 miles, and he around once every two months would not get home before the battery was flat.

Clearly the manufacturers had way over estimated the range, and he never used the cab heaters as dressed to be outside.

The problem is things move on, look at the Renault Kango long wheel base electric van today has 170 mile official range, 2017 there was a huge chance, with a faster charger and a heat pump for cab heating, however clearly not asking about electric vehicles your asking about solar panels.

The point is however because a solar panel fitted in 2010 produces X kWh it does not mean the same applies to one fitted in 2022, so all we can go on is the manufacturers claims, what we can however do is look at their claims in the past and see if they were true, and if claims in the past were wrong, we can assume claims today are also wrong.

Shakespeare said the evil that men do live after them, the good is often interned with their bones, so where we know firms and governments have lied we have to assume they are still lying.

 

[JohnW2]

...The point is however because a solar panel fitted in 2010 produces X kWh it does not mean the same applies to one fitted in 2022, so all we can go on is the manufacturers claims, what we can however do is look at their claims in the past and see if they were true, and if claims in the past were wrong, we can assume claims today are also wrong.

Quite so. Whatever other information/data one uses as the basis for one's calculations and decision-making, one most certainly should not rely on 'claims' made by the manufacturers or sellers/fitters of PV systems.

However, that does (should) apply to most things in life, so I'm not sure why so many people seem to be so naive/'taken in' when it comes to PV.

Kind Regards, John