Home Solar Thermal (hot water) System

I have now had a medium sized, professionally installed, solar hot water system installed at my house. This is because I have been so impressed with the idea of solar energy, that I decided I wanted a thermal system large enough to provide all our hot water, in the summer months, for the whole house. It was fairly expensive, but I believe it was worth it, as it reduced our carbon footprint still further and I am hopeful that the new Renewable Heat Incentive (RHI) will give us a small financial payback as well.

The system was installed for me by a local firm called Solarworks who I would fully recommend to anyone. Mark, the MD, worked hard to give me exactly what I wanted and nothing was too much trouble for him and his team.

I had seriously considered doing all the work myself, but then I realised that to qualify for the local authority grant and the RHI payments, I would need a professional MCS approved installation. Also the work had to have Building Regulations approval, so I filled in the appropriate forms in advance and after an inspection of the completed system, we were all legal and certified.

Thermomax HP200 tubes Thermomax HP200 tubes from ridgeline

The system uses 30 x Thermomax HP200 evacuated tubes on the main WNW facing roof. This is not the ideal direction, but was all I had available, as my ESE facing roof was already used for my large solar PV system. I chose to have evacuated tubes, rather than flat panels, because I wanted to harvest as much energy as I could in cold conditions.

Solar thermal equipment in loft Loft gauges and pump

My hot water was originally heated just by a condensing gas boiler, but now the boiler only fires up in the early evening, to top up any shortfall from the solar system, particularly in the winter months.

Airing cupboard cylinder and controller Flow gauge

The airing cupboard houses the new 197 litre hot water cylinder, with 3 coils heating fitted and the controller. The pump, pressure gauge, flow meter and expansion vessel are up in the loft.

Controller Roof manifold

The controller switches on the pump when required and regulates the speed, depending on how much heat is available. I chose the option to have an extra heat sensor fitted on the HW return, to enable the controller to give an indication of heat generated in kWh. The system produced 293kWh between 26th July and 16th October 2010. This averages out at 3.53kWh per day - not bad for a west facing roof!