Solar powered greenhouse

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Dyno
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Solar powered greenhouse

Post by Dyno » Tue Nov 21, 2017 9:39 am

I have a dream... That I can someone rig together a solar panel to heat my greenhouse in the spring so the missus doesn't go tonto with all the plants lying around the house.
I understand that a solar panel would be used to charge a 12v battery which would in turn power a fan or heater or whatever. What I don't understand is how to attach sensors to gauge the temp, solenoids to turn the heater on and off or control boards to have it all running smoothly.
Is there any sparks on here who could give me some advice?

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willard3
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Re: Solar powered greenhouse

Post by willard3 » Tue Nov 21, 2017 1:44 pm

Why not let the sun on the greenhouse heat the greenhouse and skip all the equipment?

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Re: Solar powered greenhouse

Post by Dyno » Tue Nov 21, 2017 2:18 pm

willard3 wrote:Why not let the sun on the greenhouse heat the greenhouse and skip all the equipment?
Ideally I'd live in a country where that was possible. But I can't get my plants out into the unheated greenhouse until mid may at the earliest. I'd like to heat the greenhouse over spring so the plants can go outside by a the beginning of April.

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willard3
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Re: Solar powered greenhouse

Post by willard3 » Wed Nov 22, 2017 1:54 pm

Insoilation falls at a known rate on t square foot of surface. If you try to heat a greenhouse with solar panels, the area of the solar panels may exceed the area of a greenhouse.

Is that what you,intend?

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ChilliJez
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Re: Solar powered greenhouse

Post by ChilliJez » Fri Nov 24, 2017 1:56 pm

Dyno, I understand your need! When I was keeping fish in there, I was really keen to find anything to warm my greenhouse through the winter period.

Before going down any investing, I'd have a think about how much temperature gain you need to achieve. Also, how much space you need to warm. If your plants are needing to go outside in late march and they're mostly new plants that's a lot less demanding than 20 overwinters that have to be outside by the end of february.

I'd start by minimising losses, so sealing any gaps in greenhouse glazing, draught excluders and the like. It's a pain to work with but I've used the spray insulating foam to fill all gaps.

Anything that's on the north side will benefit from a layer of insulation. Bubblewrap or polystyrene sheet. It doesnt need to let light through.

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ChilliJez
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Re: Solar powered greenhouse

Post by ChilliJez » Fri Nov 24, 2017 2:04 pm

Next up, I'd look to be harvesting the daytime warmth to be released at night. For that, I'd use containers of water, painted matt black. Water is freely available and provides a good heat sink. The matt black allows the heat to be absorbed. You do need volume. I had access to 225 litre blue plastic barrels for a while. They would be very good.

I'd plan how much space, as I said earlier, and then build a tent that was just big enough to house my plants. Don't heat the whole mansion when you only live in the east wing! By building a tent you double glaze as well.

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Re: Solar powered greenhouse

Post by ChilliJez » Fri Nov 24, 2017 2:13 pm

Those blue barrels were a waste issue for the farm. They contained teat dip for milking cattle. The farm was happy to be rid of them. Consult your yellow pages or ADAS and you will be able to find a farmer willing to give them to you. The contents are iodine based and would need thorough washing for plant watering but as a simple reservoir, no issue. And no algae! And hey! Free and functional.

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Re: Solar powered greenhouse

Post by Dyno » Sat Nov 25, 2017 9:27 am

ChilliJez wrote:Dyno, I understand your need! When I was keeping fish in there, I was really keen to find anything to warm my greenhouse through the winter period.

Before going down any investing, I'd have a think about how much temperature gain you need to achieve. Also, how much space you need to warm. If your plants are needing to go outside in late march and they're mostly new plants that's a lot less demanding than 20 overwinters that have to be outside by the end of february.

I'd start by minimising losses, so sealing any gaps in greenhouse glazing, draught excluders and the like. It's a pain to work with but I've used the spray insulating foam to fill all gaps.

Anything that's on the north side will benefit from a layer of insulation. Bubblewrap or polystyrene sheet. It doesnt need to let light through.
I'm really just looking to keep the greenhouse heated from April to May, and possibly at the end of the season. I'm under no illusions that heating through winter would be a massive undertaking, I've ruled that out.
I had thought about passive solar heating, I might give it a go this year as a test. Thanks for the advice mate.

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