Adam,
Solar panels for golf carts have been out on the market for a little while. They cannot replace the batteries they are meant to charge so there is no weight savings, only lighter batteries, plastic parts, etc., can do that. Even the best are only saving %'s of recharging costs.
Additionally, most of these existing panel systems are incredibly expensive, I've seen some at $1,800.00. So, if you're a club who presently leases carts and want solar, be prepared to spend quite a bit more per season per cart.
A club that owns its own fleet might do better if they keep the carts for several years or trade the carts but keep the panels.
Right now I think it's just like buying a Prius, you don't save jack but you do look 'green'.