Some Maths - PV
There is still a decent payback on pv..... and remember this maths takes no account of increasing electricity costs.
Currently:
A 3kw well-orientated system produces 900 units per kwp = 2,700 units per year, which earn 43.3p FIT = £1,169
Say, 50% of the units are exported, so 1,350 units earn 3.1p = £42, and 50% are used meaning that 1,350 units are not bought from the Grid at 15p per unit = £202
The total savings and earnings are £1,413 pa
The cost of the system would be £4k a kwp = £12,000. There is therefore an 8.5 year payback, or 11.7% return
Planned changes to FIT in Dec 2011 (now March 2012), though not affecting billing until April 2012:
Only the FIT changes to 21p so FIT now = £567
Exported = £42
Savings on purchases = £202
The cost of systems will drop to £3k a kwp (according to Energy Saving Trust, others think more) = £9,000. Therefore the payback is 11 years, or 9% return.
In short, not as good but still not bad. Things will settle.