Solar Thermal, PV and FITs. What’s it all about?

Find out all about it; from fitting solar thermal panels to photovoltaics for power generation.

What does it cost, what are Feed-in tariffs (FITs), how much power can I generate and what is the pay-back time?  This is the story of one Salisbury couple’s personal experience.

“It was a long and dark December, from the rooftops I remember there was snow, white snow………”

Yes (with apologies to Coldplay), when it snowed, the sun could not penetrate the thick white layer until Jimmy wielded a long-handled brush and removed it!  From dark and dismal December when solar generation was at the annual minimum of 35 units for the month (see graph below) we seem to have turned the corner of winter and January has been much brighter.   However the potential for winter generation when the weather is clear and sunny was demonstrated by the only 3 dawn to dusk sunny days in December when we generated 5 units on each day and Sunday 30^th January when 6 units were produced.

We took our first steps into harnessing the sun’s power by installing 3 panels to provide hot water in  summer 2005.  Since then we have not used any gas for water heating in the summer months and it provides a useful supplement even in the winter when the water temperature often gets to over 40°C on a sunny day.  Taking it one stage further, we had solar photovoltaic (PV) panels fitted to the roof in late January 2010 and so have recently completed the first year of electricity generation.   We took the decision in late 2009 when grants of up to £2500 were still available and obtained 3 quotes for the installation, all of which were within £100 of each other, giving us confidence that we would be paying the going rate, and chose Ecofirst (www.ecofirst.net), a company based in Yeovil, to do the job.  We have a semi-detached 4-bedroomed 1950s house with a large roof area facing south in the ideal position and angle to get the maximum benefit from the sun. Installation took 3 days and commissioning another few hours on another day and then we were off.The system has 9 roof panels, an AC/DC inverter in the loft and a generation meter in the understairs cupboard where the electricity and gas meters are also housed.  (Technical details at the end for those who are interested).  The wiring was fitted neatly down a wall and skirting board in white trunking.  Scaffolding was necessary as the house has 2 storeys.

The introduction of Feed-In Tariff (FIT) payments in April 2010 as well as the grant of £2500 has made it

very cost effective even though the initial outlay of just over £10k seemed a lot of money to pay out.  FIT payments of 41.3p per kWh (1kWh=1 unit) plus an extra 3p for exported units are more generous than anticipated when the payback time for our system was estimated.  Up to early December

we had received £617 and will receive approximately another £35 for the remaining months.  Since the FIT was only available from April 2010 this is not as much as we would receive in a full year which would be over £700 for the total generated this year.  This represents a tax free return on the initial investment of almost 7% per year, and the payback time is likely to be about 14 years.  However, this excludes the reduction in electricity usage when running appliances while the system is generating, the grant we received and the annual increase in FIT so the actual payback time for us might be less than 10 years.  The FIT is guaranteed for 25 years and from April 2011 the rate will increase in line with inflation, but the initial rate for new systems installed after 1^st April 2012 will decrease, and in subsequent years decrease further so the time to get started is now! On a sunny day, we find that the system will support the use of most appliances in use during the day (fridge/freezer, computer, battery/phone/ipod/toothbrush charging) as well as those drawing a heavier current (washing machine and  dishwasher, but not at the same time).  Things that create a lot of heat like kettles, irons and hair dryers draw too much current to be completely run on solar but it contributes to the total used.  A slow cooker allows you to cook an evening meal while generating.  Any units generated that we don’t use get exported to the National Grid.  It’s much more efficient to use the electricity generated on site if

possible so where possible we wait for a sunny day to do the washing and dishwashing. In the summer months, if our solar thermal panels haven’t warmed the water enough during the day, we top up with an immersion heater before the PV panels stop generating.  It’s too early to quantify how much electricity we have saved as our meter was replaced in October.  When we have more information on this we will update this article.