Photovoltaics

In January of this year we finally did what we had been considering for some years - bought a machine for home-making electricity. Our house is ideal for photovoltaics: this half of the roof faces south, its pitch is almost perfect, and this part of Suffolk has a good sunshine record. However, by the time we made this decision the grant from the government to small energy producers such as us, the so-called Feed in Tariff (FiT), had dropped to its lowest and was about to be withdrawn altogether - so much for the UK government's green credentials!

This didn't stop us from going ahead. We considered a small array but finally chose to cover the roof with 32 panels each with its own micro-inverter, so each panel functions separately and can be monitored. This is our on-line 'Enlighten' display, showing that at 3.15pm on August 1st each panel was functioning at about 800w, and the panels had produced just over a Kw of electricity in the previous 15 minutes, bringing the day's total so far to 26.23Kwh.

Over the time we've had the array we've produced over 7 megawatts of electricity. This display shows the daily production since it was installed - the lighter the square, the more electricity produced - highlighting May 14th when we had one of our best days, producing 65.2Kwh.

We receive the FiT for all the power produced and an export tariff for 50% of it. We are also free to use all our electricity, so....

....this control panel starts our day by diverting all our home-made electricity to the immersion heater until it's hot, topping it up as and when we use it. This means that, during the summer months, we have used no gas at all to heat our hot water. When the immersion isn't working we can use our power for things like cooking - we changed from a gas to an electric cooker - charging 'phones and computers, working the bread-maker, using an electric shower, and so on. As a result we have already saved several hundred pounds when compared to our utility bill last year.

The panels are guaranteed for ten years, and have a likely working life of more like twenty. The installation should pay for itself in about eight years.