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heating a green house from solar panles.

richardleehollingsrichardleehollings Posts: 5
in Tools and techniques
Does anyone have experience of heating a green house to prevent frost with solar power and electric heating. ?. 
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  • amancalledgeorgeamancalledgeorge Posts: 2,736
    With the limited amount of strong daylight this time of year I'd very much doubt it's possible...but open to be proven wrong. If most solar lights with new improved panels can barely produce a few hours of light, heating which is much more wasteful in converting energy would seem impossible.
    To Plant a Garden is to Believe in Tomorrow
  • FairygirlFairygirl Posts: 55,117
    Did you mean putting panels on the greenhouse @richardleehollings ?
    I can't see how you could do that, but if you have somewhere else where they could be put in, it might work.
    Not sure how good it would be, but it would also depend on the location and how much warmth you need to generate. 
    It's a place where beautiful isn't enough of a word....



    I live in west central Scotland - not where that photo is...
  • wild edgeswild edges Posts: 10,497
    You'd need to use them to charge batteries and then use the batteries at night to run the most efficient electric heaters you could get hold of but the chances of having enough bright light to charge the batteries each day would be slim unless you had a lot of panels.

    I've seen DIY systems that used solar thermal panels of various types to heat a big store of water or concrete but nothing that was easy to make for most people. 
    If you can keep your head, while those around you are losing theirs, you may not have grasped the seriousness of the situation.
  • Pete.8Pete.8 Posts: 11,340
    wild edges said:
    You'd need to use them to charge batteries and then use the batteries at night to run the most efficient electric heaters you could get hold of but the chances of having enough bright light to charge the batteries each day would be slim unless you had a lot of panels.

    I've seen DIY systems that used solar thermal panels of various types to heat a big store of water or concrete but nothing that was easy to make for most people. 
    I agree.
    I remember one of the gardening programmes showed a diy setup a guy had built.
    Much as @wild edges describes above.
    He had the panels mounted on an adjacent wall and they heated tanks of water under the benches in the greenhouse with the plants on top. He said it kept his (small lean-to) greenhouse frost-free.
    I would imagine quite damp too with all that water.



    Billericay - Essex

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  • BobTheGardenerBobTheGardener Posts: 11,385
    While it could be done with solar water heating panels feeding a tank inside the greenhouse, I think you can completely forget about using photovoltaic (PV) solar panels as their efficiency is so low (~10%) and even worse when used to charge batteries which would be needed to power the heater at night.  I have a 60W solar panel mounted on one of  my greenhouses and it only provides enough power to drive a couple of 6" fans which I use to provide good airflow (that works extremely well as the stronger the sun, the faster the fans spin.)
    Some calculations:
    A 12v, 120AH fully charged 'leisure' battery (cost ~£100) could provide only enough power for a little 100W tube heater for 12 hours and it would take a 12V, 120W PV panel (cost ~£100 + charge controller ~£50) 10 hours to charge, assuming all-day summer sun.  In the winter, you'd need roughly 500W worth of solar panels to charge it in the same time period (cost ~ £500.)
    In the end you would only be warming up the greenhouse by the same amount as an old-style glass 100W lightbulb would.  That might be enough to keep it frost free if it was insulated with bubble-wrap though.  I suspect the battery would only last a few years too.
    A trowel in the hand is worth a thousand lost under a bush.
  • KT53KT53 Posts: 9,016
    I don't know if it actually works but I have seen suggestions of putting candles inside inverted terracotta flower pots.  Theory is that the pots heat up enough to keep frost out of the greenhouse. 
  • treehugger80treehugger80 Posts: 1,923
    I use a space heater type of arrangement at work.
    I have a IBC (about 1000 litres) in a large polytunnel that i've filled and then put the cap on the stop evaporation, I then painted it matt black, it warms in the sunshine and then gives out the tiniest amount of heat at night.
    I store my really tender plants directly on top of it. I work on the theory that its only frosty after a sunny day, if its cloudy or raining it tends to be warmer, the only problem comes if it snows heavily enough for it to build up on the polytunnel (small amounts just slide off).
  • natalie.roberts2119natalie.roberts2119 Posts: 2
    Maybe solar panels to make heat greenhouse is useful because I think it is safer, cheaper, and better for the environment.  
  • LynLyn Posts: 23,190
    @natalie.roberts2119 are you in USA by any chance? 
    Gardening on the wild, windy west side of Dartmoor. 

  • natalie.roberts2119natalie.roberts2119 Posts: 2
    Lyn said:
    @natalie.roberts2119 are you in USA by any chance? 
    Yeah! I'm in USA. What's up?
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