Solar water heating panels, back boiler logburner, insanely long ROI?

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  • Solar water heating panels, back boiler logburner, insanely long ROI?
  • Premier Icon BlobOnAStick
    Subscriber

    Have you investigated the new RHI (renewable heat incentive) for solar thermal, it’s the equivalent of the feed-in-tariff for solar PV?

    Stoner says it’s worth 19.2p/kW ……

    Edit: here http://singletrackworld.com/forum/topic/anyone-installed-solar-panels#post-5443307

    trail_rat
    Member

    How are your diy skills .

    Globalgti showed me how reasonable a preheater system can be done for …..circa 700 quid. Wont qualify for rhi but who gives a toss im all for microgeneration rather than the money earning. ( esp when its 4100 pounds cheaper)

    trail_rat
    Member

    Cheers – cba trawling back posts for it – links saved on works favorites 🙂

    Premier Icon geoffj
    Subscriber

    I’ve got this setup + oil. It cost me around £6k to install using mates rates from a mate who is an MCS installer.
    Fag packet estimates says it’ll save me at least £1k per year mainly in oil (at todays prices), but some RHI and some leccy savings from the summer when I don’t use the immersion.

    There are a couple of deal breakers IMHO

    1. No access to mains gas; and
    2. Access to free or very cheap logs

    The log side is also a bit of a lifestyle choice if you choose to process them yourself.

    markwsf
    Member

    Excellent info gents – favorites saved…

    Geoffi – yes, the house has no mains gas (in the street though so could be installed for a few hundred £££). Cheap / free logs maybe, but there may well be a plentiful source of broken wooden paletts from work which should burn just nicel.

    Trail rat – are you able to share “Globalgti” scheme / instructions ? I’m quite happy with / much prefer the DIY option for the panels – that would be my ideal first choice.

    Premier Icon Stoner
    Subscriber

    how do you get to £65 per year?

    If you very roughly assume that 1sqm of effective collection will collect something like 4kWh per day on average from May to September you will collect 4 x 30 x 5 = 600kWh per sq m.

    Your alternative energy source may be gas (4p/kWh) Oil (7p/kWh) or electricity (12p/kWh) so each metre will save between £24 and £72 each year. A typical 20 x 58mm array of tubes has an effective collection surface area of about 3 sq m.

    I dont know how many sqm of collection your £4,800 is buying, nor what kind of additional tank & coil and controllers the price includes. You can buy a 20 tube array for <£500.

    However, as I said on the other thread, if the RHI rate for solar thermal is 19.2p/kWh then it suggest that DECC think that solar thermal payback is v v long. But that’s for an MCS certified installation eligible for RHI. DIY’ing it though like globalti (who introduced me to the stuff) and I have done should pay it’s way.

    I have 9 sq m of collection which cost me £2k. SO I can collect more than the average 20kWh of energy I need daily for domestic hot water (9 x 4kWh = 36kWh). So if I were on Oil paying 7p/kWh for my alternative 20kWh then Im saving £200-250 year, or 8-10yrs payback.

    However that’s all moot for me as my alternative is “free” wood, but the solar installation means I dont have to lug logs around and light the furnace every couple of days throughout summer. So the solar thermal saves me time and effort instead.

    b r
    Member

    Have you considered just putting in an electric shower and then below-sink heaters for the hot water?

    FWIW We’ve solar panels that were put in +20 y/o which ‘pre-heat’ the water before it goes into the tank. We’ve also an AGA which then takes the water and heats it up, and back into the tank. But when it is off/low we’ve also an immersion on the tank.

    My folks put the panels in, not looking at payback but more that they had the money and were retiring so thought they’d keep the bills lower for when they retired.

    giant_scum
    Member

    I have done work for a mate who is an MCS installer and instead of invoicing him I have asked for a Solar Thermal system for my house.

    Through the green deal assessment you are getting a £600 money off voucher at present, So with those 2 things combined I am getting it done for ‘free’, obviously I still need to install it but will be getting a hand from my mate!

    I think cost price for the kit is about £2000.

    markwsf
    Member

    I’m considering solar water heating panels on the roof in the future, it seems like a neat solution when combined with a back boiler log burner.

    Until I made a quick internet check on the payback times for the solar water heating panel part of the plan……… 73 years until return on investment (assuming £4,800 install cost, and £65 per year payback) !

    Has anyone done this and found that it can actually be installed for a fraction of this so giving the free lunch that water heated up by the sun deserves to be?

    samuri
    Member

    We bought a house with solar panels and a log burner already installed.

    HTH 😉

    Tracker1972
    Member

    Nobody mentioned Navitron yet? They were always my first port of call for “green living” daydreams. Relatively inexpensive kit for DIYers to have a go at.

    Eyepic
    Member

    Run now… don’t look back just keep running.

    I got sucked in by Stoner’s thread ….. couple of years down the line I have solar thermal and log burner (with back boiler)as my sole heating and I bloody love it …..but it can be a lifestyle choice.

    As ever thanks Stoner…. but seriously run now … you will become addicted.

    Eyepic
    Member

    Navitron can be very good BTW.

    Eyepic
    Member

    BTW approx total electricity bill for year £720 no gas or oil in my house.

    But I chop loads of wood.

    Premier Icon mikewsmith
    Subscriber

    Just moved out of a house with Solar Hot water. Down here in Tas we get about 2500 hrs of sunshine per year (http://en.wikipedia.org/wiki/Climate_of_Tasmania) south of England hits around 1900 (http://en.wikipedia.org/wiki/Climate_of_the_United_Kingdom)

    For over 6 months of the year we paid for no hot water with a medium sized tank and 1 panel for a house of 2 people – used for showers/taps etc. over the other 6 months we were using a short boost and that was it, only on the days over winter where we had no sun for 3-5 days was there a real problem and it relied on the electric.

    Given that conventional energy prices are rising (10%? my Dad was telling me about last night) and going up again then isolating yourself from the energy market will provide longer term returns.

    He is in the NE and looking at some home made preheat options like black drums in the sun etc. to knock some of their heating costs down.

    Premier Icon Stoner
    Subscriber

    top work Eyepic. Did I miss a pic-heavy thread about it or are you being lazy? 😉

    Bear
    Member

    Stoner – good facts and figures but if as you say 4kwh per sq m then you don’t need much more than that to heat your water (3kW immersion heater will nearly heat a medium sized cylinder in an hour or so). Possibly not from stone cold but then the solar wouldn’t be needing to heat the water from stone cold so you need less energy there too. Real world water heating is a fraction of your energy bill, space heating accounts for far more.

    You are basing your figures on what you can produce and not what you need to heat your water surely?

    Basically spend as much money as possible to reduce your space heating bill.

    trail_rat
    Member

    bear – doesnt stoner run his UFH from his heat store – ergo his space heating ? but perhaps im imagining that ……

    trail_rat
    Member

    DOUBLE POST.

    Bear
    Member

    Think so but you don’t usually need space heating when the sun shines! Also solar into a thermal store of some description means more collectors, more controls, more money…..

    Back to saving it on space heating, cut down air movement, insulate.

    Premier Icon Stoner
    Subscriber

    As you say, bear, I don’t turn on my UFH until well into the down season for solar. I’m aiming at November this year and solar collection is already Virtually nill.

    As I put in my post though, although I can collect on average 4kwh per day per metre we only use on average 20kwh per day. But the range of collection can be anything between a couple of kwh a day and 50kwh. The benefit of the buffer is that ability to smooth out the peaks and troughs but have average collection remain above average consumption.

    I calculate my benefit off my forecast consumption not collection: 20kwh/day vs 35+kwh/day. I’ve calculated that in peak, cold winter I might be using over 150 kwh to heat the house. Maybe even 200 kwh.

Viewing 23 posts - 1 through 23 (of 23 total)

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