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Thread: Solar Panels - The advantage?

  1. #11
    Join Date: Jan 2008

    Location: Out on the wild and windy moors Lancs / Yorks Border

    Posts: 592
    I'm Andy.

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    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.
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  2. #12
    Join Date: Feb 2010

    Location: Moved to frozen north, beyond Inverness

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    I'm Dave.

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    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.
    Last edited by dave2010; 14-10-2020 at 15:51.
    Dave

  3. #13
    Join Date: Feb 2020

    Location: Fife, Scotland

    Posts: 160
    I'm Gordon.

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    Thanks Andy and Dave.

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

    Gordon.
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  4. #14
    Join Date: Jan 2008

    Location: Out on the wild and windy moors Lancs / Yorks Border

    Posts: 592
    I'm Andy.

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    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
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  5. #15
    Join Date: Feb 2020

    Location: Fife, Scotland

    Posts: 160
    I'm Gordon.

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    Quote Originally Posted by Andy831 View Post
    You may have already realized this but I thought it worth mentioning.
    Technics SL1000R, DynavectorXV1t, Garrard 401, Jelco SA750LB, Decca Reference, ATVM750SH, AT33Mono, Hana Umami Red, Reimyo CDP777, EarYoshino 912, Ear Yoshino 509s, JBLK2 SL5800s, ART Dram interconnects / speaker cables.

  6. #16
    Join Date: May 2020

    Location: Suffolk

    Posts: 246
    I'm Ray.

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    Quote Originally Posted by Andy831 View Post
    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.
    Last edited by StingRay; 14-10-2020 at 16:25.

  7. #17
    Join Date: Jan 2008

    Location: Out on the wild and windy moors Lancs / Yorks Border

    Posts: 592
    I'm Andy.

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    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
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  8. #18
    Join Date: Feb 2010

    Location: Moved to frozen north, beyond Inverness

    Posts: 2,602
    I'm Dave.

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    Quote Originally Posted by Andy831 View Post
    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
    Indeed 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.
    Dave

  9. #19
    Join Date: May 2020

    Location: Suffolk

    Posts: 246
    I'm Ray.

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    Quote Originally Posted by Andy831 View Post
    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.

  10. #20
    Join Date: Jun 2014

    Location: Chorley Lancs

    Posts: 14,592
    I'm Steve.

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    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.
    I just dropped in, to see what condition my condition was in

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