2006 56 elise R battery

[kazino]

Hi chaps,
have read this article

http://www.lotustalk.com/forums/f321/battery-choic...

which was very informative but some of those battery are mighty expensive compared to a Bosch battery :

41ah Bosch S3 Battery For Lotus Elise (uk 063) with 3 Year Warranty

Would this be a good option or would there be a better suggestion please.
I leave the car for long periods without starting and I park it on the road so I can't attach a trickle charger.

[kambites]

How about a solar charger?

[kazino]

I have one in the garage somewhere, do they work?