How is the introduction of an additional clean, renewable and potentially financially viable energy source, not a measurable benefit to society as a whole?
Martyn.
Because it is insignificant in the context of the actual electricity consumption of the UK. According to one of Ted's links on the green building forum there is now 630MWp of installed PV on the less than 4kWp tariff. That's about 1% of peak UK demand, which counts as negligible to me. Unfortunately that is peak capacity. Average capacity is about 10% of peak for PV, so that's 0.1% of UK demand - not a meaningful benefit and arguably not a benefit at all.
But you're answering the question in terms of todays generation and todays subsidies. What about tomorrow?
I'm not trying to be difficult, but if domestic installs become financially viable, and I believe commercial is on a tipping point right now, then future subsidies (additional subsidies) go down, and generation goes up. Regarding domestic generation, with installs close to 1% of households, and average generation about 2/3 of average consumption (2,500 & 3,600 approx), then that accounts for over 0.5% of domestic demand. Yes it's small, tiny even, but doesn't every bit count, and it's early days, with a 50% cut already in subsidies.
I'm not trying to be blind to the issues today, I'm just trying to look ahead, possibly 5 years?
Mart.