Lead acid storage = Bad.

It only really works if the panels are connected to the grid on an in / out reciprocal arrangement. If not, then the green plus is lost to the green negative of disposal of lead and acid.

Just my tupp'orth

There are a lot of "financial" companies flogging P-V investment opportunities in France at the moment due to EDF being forced by gouv.fr to buy 15%(?) of their electricity from renewables.

Not only does this seem pretty dumb in a country where 85% of generating capacity is nuclear and a further 10% hydo, but the figures being bandied about as to the annual generating capacity of a fixed sourth facing panel inclined at ~25 deg are frankly absurd.