4kW domestic PV system, home is also the office. V4home also installed and a timer on the emmersion heater which not using at the moment as there is not enough surplus electric being generated each day in April.
As a company we have non thermally bridging cavity lintels www.litelco.uk which reduce both condensation and heat loss/gain above windows where traditionally steel lintels are used, and airtightness tapes. also Road Energy Systems extracting heat and cold energy from asphalt roads etc.
If using a V4home make sure they take out of the system any electric showers or water heaters and the oven as otherwise the shower may not be hot enough in winter when water temps are low and the oven can take an age.