Hi Nick,
Welcome to the association and welcome to Rutland Water. I also have my boat at Rutland Water at the sailing club. As some one who has just bought their first boat, you have made a wise choice, congratulations.
With regards the electric engine, I have the MinnKota 50, which pushes the boat along at about 2.5 knots on full power, on flat water with no head wind. I find this enough to maneuver in and out when there is no wind. Please be aware that all these electric engines are of relatively low power and cannot cope with any amount of head wind. Of course if you have wind then you can sail !
I use a small 40 Amp sealed car battery to power mine. It is not very big but gives about 30 minutes drive at medium speed, which is plenty to dodge around the pontoons and moorings. I chose this size because it is about half the size of a car battery and is much lighter to handle. You will need to charge it at home and take it with you each time. A solar panel to recharge this kind of power drain would be the size of your cockpit. I bought my battery from Halfords and it has a handy carrying handle.
If you decide to go down the solar panel route, be careful to buy the fully flexible type as both the rigid and semi rigid ones will not bend enough to match the radius of the Parker Coach roof should you decide to mount it there. I would suggest that a solar panel will only be suitable to keep your boat battery topped up and would not be sufficient to recharge an engine batter.
In practice, I find I only use the engine on the odd day the wind dies away and I need to get back to the mooring etc. This happens about twice a year.
What is the name of your boat and sail number? I will be sailing this Saturday, hope to see you around.
Regards
Graham Ebb
235/25 Blue Jazz