Calculation is an estimate (using 19.5 kWh and 39 kWh capacities) based on typical use of electrical appliances as provided by the Silicon Valley Power Appliance Energy Use Chart. Customer experience will vary based on location, actual usage and system size. SunPower does not warrant or guarantee this performance. Some appliances may not be compatible with storage system. Your SunPower installation contractor can help you determine which appliances and devices are compatible.