The average cost per watt ranges from $2. 50, including equipment, installation, and any other necessary components. For example, a 10 kW system might cost around $25,000, resulting in a cost of. Each year, the U. Department of Energy (DOE) Solar Energy Technologies Office (SETO) and its national laboratory partners analyze cost data for U. These benchmarks help measure progress toward goals for reducing solar electricity costs. A solar battery storage system costs between $10,000 and $20,000. National Renewable Energy Laboratory (NREL) at www. Solar battery prices are $6,000 to $13,000+ for the unit alone, depending on the capacity, type, and brand. A home solar battery storage system connects to solar panels to store energy and provide backup power in an. It really comes down to how much you're paying for each unit of power, according to Robert Flores, a solar expert at The University of California, Irvine.