solar panel powered heat sink for your greenhouse

i thought this was such a fantastic idea to heat your polytunnel or greenhouse and such a simple idea. if any of you remember a tv programme called its not easy being green on bbc 2 a few years ago, basically the overall idea was to radically reduce our carbon footprint in every day life. dick strawbridge took on a farm in cornwall and made his own electricity, compost loos (not for everyone i know) water supply to his house and own bio diesel amongst many many other brilliant ideas. you can apply this to any greenhouse or tunnel to bring the temperature in the winter significantly so you can keep growing all year round. make it as big or as small as you want :)


greenhouse heating system using a 10 Watt PV Solar Panel, a 12V battery, a small fan, some PVC waste pipe, and 1 cubic metre of crushed glass.

The aim of the greenhouse heatsink is to keep the greenhouse warm at night, and also to keep the greenhouse from getting too hot in the day.

Making a Greenhouse Heatsink System

A hole - the bigger the better, but ideally 1 metre wide and deep - is well insulated (using polystyrene and foil) and filled with anything through which air can pass which stores heat. Dick Strawbridge used crushed glass, however pea gravel (available from builders' merchants and pictured above) could be used instead as could small pieces of metal, small recycled bottles of water, fire bricks, etc.
Note that if a material feels cold to the touch, it will work well as a heatsink/heat store.

The solar panel charges the battery which in turn drives a small recycled PC cooling fan (shown above) 24 hours per day. The fan sucks air in from the top (apex) of the greenhouse where the air is hottest and pumps it through the 38mm standard PVC waste pipe into the base of the heatsink hole. The hot air then rises through the heatsink warming the heatsink material and cooling the air which emerges through a vent (e.g. an old chimney pot or waste pipe) and into the greenhouse.

At nighttime the now cool air at the top of the greenhouse is pushed through the now warm heatsink heating up the air and cooling down the heatsink material. This warm air then passes through the vent into the greenhouse where it helps to keep up the temperature.


give it a go and you should see results straight away and reduce your heating bills and more importantly your carbon footprint!