|1.35kWp Solar PV using Kyocera 135W panels + 2kWp Solar thermal using 100W Thermomax tubes.|
|3.5kWp Solar PV, using Hyundai 250W panels.|
|The limescale-coated bulb at the bottom is very hot!|
|The current-sensing transformer is the black thing around the red wire, sitting on the black fuse.|
As the company that installed the upgrade had previously only installed systems to properties previous without Solar PV, they thought that I would receive the current Feed-In Tariff rate, which is 16.56p/kWh, including 50% export Tariff. This is much lower than the Feed-In Tariff rate that I was receiving for my 1.35kWp installation, which was 47p/kWh, including 50% export Tariff. They suggested that I phone ScottishPower (my energy supplier) for clarification.
The good news is that I will receive 47p/kWh for 1.35kW and 16.56p/kWh for the additional 2.15kW, making a net Feed-In Tariff of 28.3p/kWh, including 50% export Tariff. That's 71% more than I thought I'd get.
Based on PVGIS data (postcode-dependent), the system should generate 3,210kWh/annum. That's £908/annum in Tariffs + ~£240/annum in saved electricity consumption + ~£50/annum in saved gas consumption = ~£1,198/annum. The system cost £7,700 including VAT, so ROI is 15.6%. Feed-In Tariffs increase by ~5%/annum and energy prices increase by ~14%/annum, so the system should pay for itself in ~5 years.