Asking yourself "how big should my solar panel system be?" Want to know "how do I size my home battery?" You've come to the right place. These solar panel calculators will help you with sizing your renewable energy solar panel system, including figuring out the number of solar panels and what size battery you need for your system. Your monthly electric consumption plays a big part in determining your solar array size calculation, so to get the most out of altE's solar panel and solar energy calculators, make sure to have your monthly electricity bill handy.