Key specifications to consider when evaluating solar panels are the wattage or power rating, efficiency percentage, operating voltage, current output, and the temperature coefficient that indicates how the panel's performance is affected by temperature changes.
Broadly speaking, there are four different types of retailers where you can shop for solar panels. To start, check out websites (like Amazon), big-box stores (like Costco and Sam's Club) and home improvement stores (like Lowe's and The Home Depot), and then see what solar.