Solar battery charger for 2011 X3

Hi Everyone,

My dealer replaced the battery on my 20 month old 2011 x3 and told me that I'm not driving the car enough and need to hook it up to some type of battery tender on a regular basis to keep it fully charged. Since I live in NYC and have no garage, I have to park my car in the street. This being the case, I can't easily connect a regular battery tender or trickler to my car by running an electrical extension cord from my house to my parked car.

My question: can I use one of the solar powered battery tenders I've heard about and, if so, what size and model do you all recommend?

Thanks!