I am planning to construct a solar power ventilator. But before constructing it I have quite a bit of queries. If I use only one 12 volt DC solar panel, how many fans would I be able to operate? Is there any need of a battery and a charge controller? What can be done with DC input? Also tell me what to do with the setup of the whole system while making solar power ventilator? I would really appreciate an early response. Thanks.