On 1 July, 21:23, "tim...." wrote:
I guess that this is off topic but I suspect that I will find some experts
here.

My sister has had a man around to quote for this and I've been tasked with
checking out if what she was told makes sense.

She has a bungalow with a shallow sloped roof and the quote was to install
14 panels on an Easterly facing roof because the Southerly facing one is
shaded by a tree. *So the figures a

Expected output 2928 kWh per year.

Returning 41.3 feed in tariff plus a saving on her electric bill of 50% of
the output at say 12p and the other 50% output gains 3p from the electric
company.

The prices a

a) A "leasing" scheme whereby the householder pays an "installation" fee of
2610.00 and receives the "free electricity plus the "3p" but the company
receive all of the 41.3 feed in tariff.

b) Outright purchase costing 18237.00 whereby the householder keeps all of
the returns.

I calculate that (a) returns around 220 pounds (8.4%) and (b) returns 1430
pounds (7.8%).

So the question is, are these figures actually achievable and is the cost
price competitive?

Does anybody know?

tim

Ask on what basis they arrive at the expected output. I think you will
find its a back of an envelope calculation based on theoretical
maximums which are never achieved in reality.
Not using a South facing aspect is going to approximately halve the
available energy so either the tree goes or forget it in my opinion