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Thread: Domestic solar panels

  1. #1

    Domestic solar panels

    Domestic photovoltaic panels are still very expensive to purchase and install. They produce most of their electricity in the middle of the day, when families normally need it the least. So what often happens is the owner either sells it to the grid for close-to-zero, or store it in a battery (very expensive, and with limited lifespan).


    Payback time seems to be 10-15 yr.


    Of course there other aspects beyond the economic one, enviromental or geopolitical for instance.


    What's your opinion on the economy of domestic solar PV panel, with or without battery, good or bad?

  2. #2
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    We got our panels back in 2011, when the feed-in tariff was 41p/kWh (if I remember correctly), so we sell our power to the grid for a reasonable sum, not "close-to-zero". We get around £900/year from the feed-in-tariff, from 2.22kW installed capacity, which cost £8000 to purchase and install (and could have been near double that if we hadn't hunted around for special offers). So, including the savings from reduction in our bills, we must be getting fairly close to payback, after 7 years.

    I wanted them mainly for environmental reasons, but I only decided that I could afford to make the investment after a friend who's a Professor of Economics had them installed on his house!

    I don't know anything about batteries, but I believe the technology has advanced a lot since we had the panels installed. My main concern is that the inverter is only guaranteed for 10 years, and that would be quite expensive to replace if it went wrong.
    In his lifetime he suffered from unreality, as do so many Englishmen.
    Jorge Luis Borges

  3. #3
    Sure, with the older FIT things used to be different.
    Now that politics has decided to lower the FIT ...

    I'm tempted to get them but not yet fully convinced ...

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    Master ba-ba's Avatar
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    My parents went water-heating first, later getting PV. It still confuses me when visiting I get back from a muddy run and am told 'there's enough hot water for a shower'. All mod cons!
    There's been a recent breakthrough in panels that capture energy from rain-drops to reduce power drop-off when it's not sunny, but real-world application is still a while off.
    Nic Barber. Downhill Dandy

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    I feel you're planning on selling your house soon (within 10 years!) make sure that you actually own the panels and it is not a lease agreement or similar. When doing a purchase/sale 2 years ago, the agent said he wouldn't touch a house with panels unless they were owned as they 'almost always fall through'. Parents and parents-in-law both own theirs and have a decent FIT, make back the investment within 10-15 years.

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    Quote Originally Posted by anthonykay View Post
    We got our panels back in 2011, when the feed-in tariff was 41p/kWh (if I remember correctly), so we sell our power to the grid for a reasonable sum, not "close-to-zero". We get around £900/year from the feed-in-tariff, from 2.22kW installed capacity, which cost £8000 to purchase and install (and could have been near double that if we hadn't hunted around for special offers). So, including the savings from reduction in our bills, we must be getting fairly close to payback, after 7 years.

    I wanted them mainly for environmental reasons, but I only decided that I could afford to make the investment after a friend who's a Professor of Economics had them installed on his house!

    I don't know anything about batteries, but I believe the technology has advanced a lot since we had the panels installed. My main concern is that the inverter is only guaranteed for 10 years, and that would be quite expensive to replace if it went wrong.
    We also got ours back in 2010 as it was too good an investment to miss. They've been great so far. However, we had them installed on the byre roof which has been fine. Friends had there's installed on the main roof of their house and now, at the point of selling the house, they've been asked to show the structural engineer's report that the roof is sufficiently sound to take the weight of the panels and any wind pressure, etc.. Shouldn't be a problem for them to commission one, but perhaps on some roofs this could be an issue.
    Am Yisrael Chai

  7. #7
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    Smile

    Quote Originally Posted by Gambatte View Post
    Domestic photovoltaic panels are still very expensive to purchase and install. They produce most of their electricity in the middle of the day, when families normally need it the least. So what often happens is the owner either sells it to the grid for close-to-zero, or store it in a battery (very expensive, and with limited lifespan).


    Payback time seems to be 10-15 yr.


    Of course there other aspects beyond the economic one, enviromental or geopolitical for instance.


    What's your opinion on the economy of domestic solar PV panel, with or without battery, good or bad?
    Used to be good, now not so. A quality 3.6kw system would cost about £12000-£14000 and give you 3000 units a year. At around 5p a kw hour that would give you £135. Then you save money on your bills depending on your ingenuity.

    The key is understanding the power of all your appliances and manipulating their use depending on the weather. For instance a kettle will use around 2500w but if you put it on a dull day when the panels are producing 300w you are still paying for 2200w.

    So what you have to do is think ahead. If you've got an induction hob for instance you can put it on low power and slowly heat your water. It's a bind but if you're at home it's free. You can then store some in flasks for night time.

    Washing machines are the same. You have to wait for the brightest time of day before you dare put it on. And you can't put the kettle on at the same time because the two together drain the power. Anything rechargeable like phones or computers are put on during daylight and if you have to put charge in them at night just enough to keep them going.

    A fridge costs about £50-£60 a year to run so what you do is turn it up during the day so the temp inside goes down and put the white blocks in the freezer. Then when the sun starts to go down, you turn it down and put the blocks in the fridge to keep it cool.

    On a bright cold day when everything is done you can heat the house. Just use the electric oven and open the door for an hour or so. Free central heating.

    The worst thing though is even if you become an expert, the rest of the family won't appreciate it and it'll hack you off when they start turning an excessive number of electrical appliances on at the same time. Then you'll want to chop them up into pieces for being so inconsiderate but you'll change your mind when you realise the chainsaw needs 2000w but the panels are producing only 1900w.

    Paranoia is an understatement.
    Last edited by CL; 17-03-2018 at 12:45 AM.

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    Brilliant, CL, I knew there was a reason I decided it would be too much bother trying to maximise my savings on electricity consumption.
    In his lifetime he suffered from unreality, as do so many Englishmen.
    Jorge Luis Borges

  9. #9
    Quote Originally Posted by CL View Post
    Used to be good, now not so..
    By which you mean the Govt. finally stopped shovelling money at householders to encourage them to install a grossly inefficient system...
    Last edited by Graham Breeze; 17-03-2018 at 08:12 PM.
    "...as dry as the Atacama desert".

  10. #10
    Master BritNick's Avatar
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    Quote Originally Posted by Graham Breeze View Post
    By which you mean the Govt. finally stopped shovelling money at householders to encourage them to install a grossly inefficient system...
    Spot on.

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