Green Deal really isn’t for PV or solar water heating, you’re better off claiming FIT and RHI (when available). You probably won’t be able to claim for either if you have the units installed through Green Deal.
Green Deal/ECO is good for insulation especially if you live in a hard to treat house (solid wall or off the gas network). Should be some subsidies available if living in a HTT home.
Check out page 11 for the list of qualifying measures for ECO subsidies http://www.decc.gov.uk/assets/decc/11/tackling-climate-change/green-deal/5504-which-energy-efficiency-improvements-qualify-for-g.pdf
the qualification for the subsidies are:
Affordable warmth – on a benefit of some sort (there’s a specific list of those that qualify)
Carbon reduction – anyone who lives in a HTT home. You would have to pay for the measure up until the measure stops paying for itself in it’s own lifetime – ECO provides the rest.
Carbon saving communities – homes in low income areas (the lowest 15% in the country).
Green Deal and ECO are available in England, Wales, Scotland but not Northern Ireland.