Most homes need 5-10kW systems to offset electricity bills. Optimize output by choosing south-facing orientation, proper tilt angle (roughly equal to latitude), minimizing shading, and keeping panels clean. Divide your system size (kW) by panel wattage. For 6kW with 400W panels: 6000 ÷. System output depends on three primary factors: panel wattage (modern residential panels range from 370W to 430W), peak sun hours at your location (ranging from 3. 5+ hours in the Desert Southwest), and system efficiency losses from inverter conversion, wiring. Caution: Photovoltaic system performance predictions calculated by PVWatts ® include many inherent assumptions and uncertainties and do not reflect variations between PV technologies nor site-specific characteristics except as represented by PVWatts ® inputs. For example, PV modules with better. Estimate solar system size, panel count, annual generation, roof fit, installed cost, tax credit, bill offset, payback period, and long-term savings using simple or advanced assumptions. Calculator is for informational purposes only. If you're willing to make such an investment, it may be a good idea to compare the cost of going solar versus solar savings.
