Wednesday, August 22, 2007


This could be a help in my quest to decide on the merits, ROI and enviROI, of solar: Solar photovoltaic panels could lead to cheques from your electricity supplier

It comes from a post in Treehugger, which has other worthy info.

Nice to see the UK on top of such issues, and with our weather that it can seem to work!


Dave said...

Just a little word of caution here. The average price per unit of electricity is ~8p to ~9p per KwH - that's what you pay for the power coming into your home from the mains grid.

If you have a sufficiently large and efficient PV array on your property, you can export any excess power to the grid. The problem here is that most of the major players will only offer you ~1.5p to ~1.8p per KwH for your excess power. So if you really want to make money out of it, you need to install a huge PV array grossly oversized in proportion to your property's requirements. Which, of course, means an even gigger capital outlay!

Peter said...

Caution noted. And why I am grateful to those on this blog who can add a touch of 'envi' to the 'ROI' considerations.

Of course the enviROI still looks potentially OK if one is prepared to 'invest' in becoming an energy production facility at the required scale.

Though many I suspect will not be able to afford the giga-capital required!

The question is why the gross difference in what you buy vs. what they pay? I can see some difference to allow for logistics and admin, but by a factor of 4?

Dave said...

I have to withdraw the figures I gave you - they are now way out of date - it appears that the big power boys had their knuckles rapped by central government (OFT) and are now forced to pay a much more reasonable rate!

For example, EDF Energy's Green Tarrif will now pay 7.64p per unit of electricity exported to the national grid.

Ecotricity and Good Energy will pay you 4.5p per unit you generate, whether you use it yourself or not. You so lose the right to apply for ROC's with both of these though.

In all cases you effectively require three meters, a generation meter, an import meter and an export meter. This little lot costs something like £300-£500 installed.

Lawrence Clark said...

The difference in price was fair in some ways because PV systems export power when demand is low (during the day), and produce none when demand is highest (early in winter evenings).

However, as power companies have been given their tradable permits to emit CO2 under the EU Trading Scheme, I'm sure they will be able to cope with paying a bit extra!