Solar Panels - The advantage?

[WullieD20]

Just wondering if anyone can put any sort of figures against the value in Solar panels, now that they've been around for a while? Is it possible to apply an estimate of their contribution and subsequent savings over a standard electrical supply bills?

The reason being that I have a neighbour who has had their system for a few years (exact date unknown, but not more than around 6 or 8 years) and has recently had two 'inverters' condemned as not functioning. Outcome: two new inverters will cost £4k (£2k each) and I can't imagine that her Solar panels have contributed £4k in the time the system has been installed? (despite the figures month by month as to how much the panels are earning - and of course to cost of the original installation!).

Subsequent outcome if this is the case is that her solar system is unviable and pointless.......? Her house is a 40 year old bungalow with 3 bedrooms, lounge, and usual spaces like small utility room and cupboards.

Any opinions or examples gratefully received guys. Thanks.

[StingRay]

Just wondering if anyone can put any sort of figures against the value in Solar panels, now that they've been around for a while? Is it possible to apply an estimate of their contribution and subsequent savings over a standard electrical supply bills?

The reason being that I have a neighbour who has had their system for a few years (exact date unknown, but not more than around 6 or 8 years) and has recently had two 'inverters' condemned as not functioning. Outcome: two new inverters will cost £4k (£2k each) and I can't imagine that her Solar panels have contributed £4k in the time the system has been installed? (despite the figures month by month as to how much the panels are earning - and of course to cost of the original installation!).

Subsequent outcome if this is the case is that her solar system is unviable and pointless.......? Her house is a 40 year old bungalow with 3 bedrooms, lounge, and usual spaces like small utility room and cupboards.

Any opinions or examples gratefully received guys. Thanks.

It depends when they were fitted, the Govt. payments have been falling. I did get a quote a few years ago but thought it was not worth it. You have to take into direction and shading as well. I think I would get back about £600 per year, that was for 16 panels (4kw), believe it will be lower now. The cost of those invertors seems too high, here is something about them: https://www.theecoexperts.co.uk/solar-panels/inverter-costs

https://www.moneysavingexpert.com/utilities/free-solar-panels/

[WullieD20]

Hi Ray. Thanks for that.
I'm fairly unknowledgeable about solar stuff (don't have it!), but was an engineering analyst in a past life so did a bit of digging.
Inverters can cost anything between £500 and £5000, depending on lots of things....... But I don't know if a scammer can just pull a plug or switch something off to create a panel indication of a red lamp and information telling that there is no contribution - indicating a fault with the unit!

[StingRay]

Hi Ray. Thanks for that.
I'm fairly unknowledgeable about solar stuff (don't have it!), but was an engineering analyst in a past life so did a bit of digging.
Inverters can cost anything between £500 and £5000, depending on lots of things....... But I don't know if a scammer can just pull a plug or switch something off to create a panel indication of a red lamp and information telling that there is no contribution - indicating a fault with the unit!

I don't have them either, don't know a great deal. I wonder if you still get the Govt. payback even if they are not working?

How did she know the invertors were not working?

[WullieD20]

I wonder if you still get the Govt. payback even if they are not working?. . . Good question, well asked!!! :D How would they know?


How did she know the invertors were not working?. . (Probably the reason for my initial question). She had a 'health check' undertaken by an independent 'power consultancy'. . .!! As I said in my OP the displays on both inverters were showing red lamps and messages indicating no power contribution. The company produced photos of both displays, but again, as I said, I don't know if these could have been contrived (or even photos form other inverters?), but I'm a sort of cynical twat.....(especially with my enquiring background).

[StingRay]

. . . Good question, well asked!!! :D How would they know?

. . (Probably the reason for my initial question). She had a 'health check' undertaken by an independent 'power consultancy'. . .!! As I said in my OP the displays on both inverters were showing red lamps and messages indicating no power contribution. The company produced photos of both displays, but again, as I said, I don't know if these could have been contrived (or even photos form other inverters?), but I'm a sort of cynical twat.....(especially with my enquiring background).

This independent 'power consultancy' is now quoting £4k to replace them? If so I would be very wary.

[MikeMusic]

Sounds like a stitch up to me
Get other suppliers in for a check.
Do not say the inverters are gone and see what they say

[Pigmy Pony]

This independent 'power consultancy' is now quoting £4k to replace them? If so I would be very wary.

Agreed. That quote is truly shocking. Years ago I was installing the panels, but wasn't involved in the electrical side. Even so inverter prices were nowhere near that, and not wanting to sound negative, I'm positive that current prices aren't much more. And as the installation of the new inverter is a straight swap, labour wouldn't cost the earth.

Sorry couldn't resist :)

[WullieD20]

Thanks all.

I can't and I wouldn't disagree with all the comments related to the possible 'scam' situation. But, with experience, would users of solar panels stand up and declare that they actually 'save money'?

Having read the links that Ray provided early on, it appears that some systems wouldn't pay for themselves in the users lifetime.....!!! Wot's the point?:scratch:

[StingRay]

Thanks all.

I can't and I wouldn't disagree with all the comments related to the possible 'scam' situation. But, with experience, would users of solar panels stand up and declare that they actually 'save money'?

Having read the links that Ray provided early on, it appears that some systems wouldn't pay for themselves in the users lifetime.....!!! Wot's the point?:scratch:

To be fair if you had got them over 6 years ago you would have got a decent payback but since then it has been reduced by the Govt.

[Andy831]

I have 12 panels in two arrays of 6. I bought them when the gov were offering max incentives and currently get about £0.54p per unit produced this amounts to about £900 a year. I have individual invertors for each panel which can be monitored for performance from my kindle. Each invertor is guaranteed for 20 years (Enphase).

I also use an AirSource Heat Pump which burns around £900 of electric to keep the house warm and supply us with hot water. So the panels pay for the electric.

As regards payback well the panels will take about 9 or 10 years for payback and the heat pump a lot less than that as the Gov pays me £1000 a year for 7 years under the RHI scheme meaning the heat pump only cost A grand.

Tell your neighbour to investigate Enphase invertors.

[dave2010]

We have had experience of installing two systems - on two different houses. If we only look at the obvious bottom line we may have lost money, as the installation cost exceeded the FiT repayments and the savings in electricity. However, we may have gained because we sold our previous house, and possibly the installation made that more attractive to buyers. Generally however, I think that buyers may take these installations, but are not usually willing to pay for them.

We installed another system in our recently purchased house - and it was much cheaper than the first. We still get a very small FiT return, but we were surprised to notice a definite drop in electricity use. With the FiT my calculations suggest a break even point of about 10-12 years, but without the FiT break even will probably take 15 years.

Regarding inverters, they are generally supposed to last between 10-15 years, though whether newer ones will last longer I don't know. Someone we know has a system comparable in age to our first one. What happens is that after a few years cold callers start to contact home owners, saying that the systems may need maintenance, and that they can be made more efficient. One efficiency measure suggested is to wire the panels in parallel, rather than in series, and this needs new control equipment. Personally I feel that these people are generally scammers, as they always try to suggest that changes are necessary. It seems quite possible, indeed likely, that the new configurations are slightly better, but the increased efficiency does not give such an increased output to match the substantial increase in overall capital costs. However, if the original systems really are failing, then having a new inverter does make sense, but should by now be a relatively low cost part of an update programme.

One other modification which can be done is to install a stand alone battery. Whether this makes sense or not is also open to question. typically the batteries are £7-8k with a Tesla battery and installation costs. Probably the Tesla batteries are good, but there would not be too much of a cost saving by storing electricity so any payback time might well be 20 years - assuming the batteries themselves don't need replacing. Where such a modification might be useful is in any area where power cuts are perhaps quite frequent, and if there is equipment which needs to be kept running.
For example, if food in freezers is vulnerable, a power cut can easily cost £500 in terms of lost food, and a battery might mitigate against that. It is nevertheless debatable whether most people would really feel such a battery is a worthwhile capital "investment".

One reason why people might install such equipment is because of a belief that in the long term this would be a good thing to do, but in terms of short to medium turn returns, these are not going to deliver.

Some people might benefit from having a solar hot water panel installed. Those are relatively cheap, and can make a significant difference to hot water supplies. However, that only really helps if a household uses a lot of hot water. Many appliances which could use hot water - such as washing machines and dishwashers are nowadays often only made as cold fill units, so there is very little benefit to be gained. However, these panels should offset the use of oil, gas or electricity for water heating, and should provide an environmental benefit.

It's still quite a complex issue though, as solar panel systems for hot water are often not compatible with other forms of domestic heating, and trying to integrate them into a system may be hard, or impractical, or benefits may be cancelled out by other factors. Air source heat pumps are probably the way to go for domestic heating, but then there may be limited benefit in also having a solar water heating system.

[WullieD20]

Thanks Andy and Dave.

Both replies make a good read, a lot of sense and help to make informed decisions. Cheers,

Gordon.

[Andy831]

Gordon

Just one other point, the further North you are (I note Dave is North of Inverness while you are in Fife) the less the panels will generate due to the suns elevation and time above the horizon. Ie If Dave and I have the exact some system facing the same way with me atop the Pennines in Yorkshire and Dave North of Inverness then my panels would make marginally more electricity.

You may have already realized this but I thought it worth mentioning.

Andy

[WullieD20]

You may have already realized this but I thought it worth mentioning.

:thumbsup:

[StingRay]

Gordon

Just one other point, the further North you are (I note Dave is North of Inverness while you are in Fife) the less the panels will generate due to the suns elevation and time above the horizon. Ie If Dave and I have the exact some system facing the same way with me atop the Pennines in Yorkshire and Dave North of Inverness then my panels would make marginally more electricity.

You may have already realized this but I thought it worth mentioning.

Andy

Is that correct? In winter yes the days are shorter but in summer the days are longer than down south. I was surprised how late the sun set in Scotland in May.

[Andy831]

Ray it was an off the cuff comment that I had not particularly thought through, it was not based on any science LOL.

The Panel manufacturer's will tell you the panels require daylight to work rather than sunshine or heat.

In saying all that I distinctly remember a TV programme about PV questioning the viability of panels anywhere north of the Midlands (Birmingham)

When I look at the performance of my panels I do find that at the extremes of the day the panels produce very little power and really get going in the middle of the day when the sun is high in the sky, similarly in June / July when the sun its very high the panels produce far more power than they do on a similar Sunny December day when the sun is a lot lower in the sky.

So maybe whilst the summer daylight time is longer in Northern Scotland maybe because the sun elevation is lower my assertion may still be correct.....but I am no scientist LOL.

Andy

[dave2010]

Gordon

Just one other point, the further North you are (I note Dave is North of Inverness while you are in Fife) the less the panels will generate due to the suns elevation and time above the horizon. Ie If Dave and I have the exact some system facing the same way with me atop the Pennines in Yorkshire and Dave North of Inverness then my panels would make marginally more electricity.

You may have already realized this but I thought it worth mentioning.

AndyIndeed I think you would get more output in Yorkshire than in Inverness. There are several factors. One is the strength of the sun - and also the cloud clover, and another is the day length. Overall though I would expect less output further north.

What you need to look at is a table of insolation - such as this one - http://applet-magic.com/insolation.htm

Having said all that though, I think there is some merit in having panels even up as far as we are in Inverness. This depends on the costs of the panels continuing to drop, or at least stay as low as they are at present. If the panels were more expensive, then it probably wouldn't be worth it in financial terms, yet if the panel prices drop even further and the inverters and other auxiliary equipment continue to become cheaper, then solar electricity generation would become viable in almost all of the UK.

Regarding giving some of you information to "help" you decide whether to go for panels or not - I think there's an element of beliefs and priorities here. I would say if you have spare cash and care about the environment then go for them. If you don't have spare cash, and definite pressing needs in other directions, then spend your money on those first. I probably don't need to tell anybody who doesn't care about the environment what to do.

FWIW the government ought to be insisting that new build houses have this kind of system built in - and preferably with the currently rather expensive units which look like, and effectively are, tiles. Houses should also have much higher insulation standards, as that's where a lot of the energy in the UK is wasted - domestic heating - and it would not be unreasonable to have building standards which mandated some form of energy efficient heating - which currently I think means air source heat pumps or gas heating (even though gas is a fossil fuel, and would increase CO2 emissions) - though if insulation were done to much higher standards, then there wouldn't be so much need for heating anyway. It is possible to design and build houses which have very low requirements for heating, but enthusiasm for such in the UK is really rather low. There are experts in so-called passive houses, who have designed and built houses with minimal requirements for energy for heating. Using electricity for heating unless there is a considerable glut of electricity at any time, is nonsensical, though in the future the may be sufficient generating capacity for such a glut to be a reality. I wouldn't expect generating capacity to reach that state for at least 50 years.

Remember also that whether you have panels or windmills or whatever to generate electricity, or offset the use of electricity of gas with solar heating panels, these are all forms of micro generation. A question remains whether it would be better in efficiency terms to have very large macro generating systems, either for electricity or heat, constructed and run by public/private enterprises, and then use distribution networks to use the energy effectively. There would be losses in the distribution netowrks, but they might be offset by greater generating efficiency. One approach which has barely been looked at in the UK is the use of district heating - which is a feature of some other cities, such as Copenhagen, where power stations burn fuel from waste (waste that can't otherwise be recycled) and the surplus heat is then used for heating local offices and houses, rather than being used to heat up local rivers and disturb local ecosystems.

[StingRay]

Ray it was an off the cuff comment that I had not particularly thought through, it was not based on any science LOL.

The Panel manufacturer's will tell you the panels require daylight to work rather than sunshine or heat.

In saying all that I distinctly remember a TV programme about PV questioning the viability of panels anywhere north of the Midlands (Birmingham)

When I look at the performance of my panels I do find that at the extremes of the day the panels produce very little power and really get going in the middle of the day when the sun is high in the sky, similarly in June / July when the sun its very high the panels produce far more power than they do on a similar Sunny December day when the sun is a lot lower in the sky.

So maybe whilst the summer daylight time is longer in Northern Scotland maybe because the sun elevation is lower my assertion may still be correct.....but I am no scientist LOL.

Andy

It is an interesting one. I know near the equator the sun goes down fast and it's gets dark much quicker than say 4,000 miles north or south of the equator. In Iceland in June and July it does not get dark at all.

[Pigmy Pony]

Solar panels need sunshine (as opposed to daylight) to work optimally. The clue is in the word 'solar'. I was told at the time I was installing panels that if they are all on one 'string', and one panel becomes shaded by a chimney for example, none of them work. I'm not an electrician (part P or otherwise), so I don't know if he was having me on.

The further south you are, the more overhead the sun will be, and with less atmosphere to diffuse the solar energy, the more effective it will be.