We’re at the stage now where we have mounted the solar thermal panels on the roof of the building. We’ve installed 5m² of these Scottish-made flat plate solar panels from AES Solar which will harness the sun’s energy to provide hot water, but will also be used for space heating.
We’ve installed the highly-efficient panels at a fairly high angle to capture as much winter sun as we can to maximise the energy the panels generate. The panels are connected to insulated pipes that run across the roof and down into the plant room.
This is where our chosen system gets really clever.
A normal household water tank will have one boiler coil that works to heat the water. A normal solar tank will be a twin-coil version, with the boiler coil and a second coil which water heated by the solar panels will run through, giving two different methods of putting heat into the tank.
We’ve got a really smart Solar 3C cylinder that has an additional third coil that is designed to take the heat out of the tank and into the underfloor heating loop when we’re not using the hot water, thus using the solar panels for space heating.
As we have a highly-insulated house, we don’t need high flow temperatures in our underfloor heating in order for the house to feel comfortable warm, so even in winter months when the solar panels may only be able to heat the water to around 35° (compared to 50-60° in the summer months), it’s likely to be enough to heat the house.
This is one of the secrets to low energy architecture. You want to exploit all the little bits of energy that you have ambient around the building to reduce your reliance on fossil fuels.