We have a wood pellet boiler, solar (thermal) panels and thermal store. Pellet boiler working really well as are the solar panels. The thermal store is undersized however but am learning to live with it!
Also now have solar PV (3.9 kWp system with microinverters, installed April 2011).
Previously we had an oil fired combi-boiler and no solar panels. Pay-back time was not the major consideration in our case as at current energy prices the pay-back time looks to be around 15 to 20 years! Just trying to do our bit I suppose.
I am a GOFER and spend most of my spare time helping others with DIY type jobs (Haven Helpers voluntary project) or doing similar in my own home.
Have installed additional loft insulation and internal insulation to exterior walls and sloping ceilings in our dormer bungalow. Also have fitted secondary DG to Velux windows and capped redundant chimney.
Ensure that you use one person/company to do all the work rather than different people in a piecemeal fashion. Check what installations the proposed installer has actually installed and go and talk to their clients (if possible). I have an uneasy feeling that my wood pellet boiler/solar thermal installer has learnt a lot at my expense!
Re: solar PV. It is probably common knowledge now but back when I had my solar PV system installed I was not told that I had to register with my proposed FIT suppler asap after installation. Hence I lost about 6 weeks payments. To their credit the PV installers agreed to reduce my bill by the same amount that I had lost.