Before you purchase the components to build a solar power system, you need to determine how much electricity you expect to use. To do this, collect your electric bills from the past several months, and look for your average usage per month and year. Plan to purchase a system that will deliver more power than you. Rigid solar panels for rooftop installation are relatively lightweight and designed to last at least 25 to 30 years. Still, you should ensure that your roof structure is sound enough to hold. Once you know what you need, you can work with a manufacturer or retailer to identify the right components to deliver the electricity you expect to use. For off-grid solar power systems, the equipment you'll need includes the. If you're going for a fixed installation, you'll most likely install your solar panels on the rooftop. Begin by determining the optimal rooftop locations and. The battery or batteries in solar power systems store the electricity your solar panels generate. Depending on the energy delivery you need, you.