Photovoltaic Solar Planning Guide
A photovoltaic project starts with the daily load. The load tells you how much energy the site uses each day. A good estimate includes appliances, pumps, lights, tools, and standby loads. It also includes future growth. This calculator uses daily or monthly energy data. It then adjusts the load by your safety margin.
Panel and Sun Hour Sizing
Panel sizing depends on peak sun hours. Peak sun hours are not the same as daylight hours. They describe usable solar energy. A site with five peak sun hours can produce more energy than a cloudy site with three. Losses also matter. Dust, heat, wiring, inverter loss, and shade reduce output. The calculator combines these values into one performance factor.
Array Capacity
The required array size is the load divided by useful sun energy. After that, the tool rounds panel count upward. Rounding upward is important. You cannot install part of a panel. The installed array may be slightly larger than the exact need. This helps during weak weather and seasonal changes.
Battery and Inverter Planning
Battery sizing is based on backup energy. Autonomy days show how long the system should run without strong sun. Depth of discharge protects battery life. A lower discharge limit needs more battery capacity. The battery voltage converts capacity into amp hours. This helps compare battery banks.
Inverter sizing checks peak load and array ratio. The inverter must serve the highest expected AC load. It should also match the DC array size. Charge controller current is estimated from array power and battery voltage. Extra current margin is added for safe design.
Cost and Review
Cost results are only estimates. Local labor, mounting, permits, cable distance, and protection devices can change the price. Incentives lower net cost. Energy savings depend on self consumption and export value. Payback improves when daytime loads use more solar power.
Use the results as a design starting point. Check local codes before buying equipment. Confirm roof strength, shade, orientation, and utility rules. A qualified installer should verify string voltage, grounding, disconnects, protection, and inspection needs. Good planning prevents undersized systems. It also avoids expensive overbuilding. Review the assumptions often. Solar performance changes with weather, seasons, cleaning, and load habits. Store the input sheet. Compare the result with real bills after installation each year.