I just got a 7watt panel and a 10000 MAH battery. That should do fine I think. Its just her Ipod, my Iphone, and a Go PRo. If not, I will add a second 7 watt panel and battery to her bike I spent 36 bucks on both. Thank you Amazon. Oh I forgot about our lights they are USB too, but we wont use them much as we wont ride after dark. So only if low visibility.