actually since i was thinking of buying this rollout solar panel
http://www.ebay.com/itm/SOLAR-Flexible-Roof-Panel-124-watt-UniSolar-/280722002063?pt=LH_DefaultDomain_0&hash=item415c55d08f#ht_1421wt_1139
maybe use that to charge the batteries during the day time and then ...hmm not sure but i would like to integrate that as well