Photovoltaic Panel System Calculator
Estimate the solar panel wattage, number of panels, and battery storage needed for your energy consumption.
Calculation Results:
Total Daily Energy Needed: 0 Wh/day
Total Panel Wattage Required: 0 Wp
Number of Panels Needed: 0 panels
Estimated System Cost (Panels & Inverter): $0.00
Battery Storage Estimates:
Required Battery Bank Capacity: 0 Wh (0 Ah at 0V)
Number of Batteries Needed: 0 batteries
Understanding Your Photovoltaic Panel System
A photovoltaic (PV) panel system, commonly known as a solar panel system, converts sunlight into electricity. This calculator helps you estimate the key components needed for a grid-tied or off-grid solar setup based on your energy consumption and local solar conditions.
How Solar Panels Work
Solar panels are made of photovoltaic cells that absorb photons from sunlight and release electrons, generating an electric current. This direct current (DC) electricity is then converted into alternating current (AC) by an inverter, making it usable for household appliances or feeding into the electrical grid.
Key Factors in Sizing Your System
- Average Daily Energy Consumption (kWh/day): This is the most crucial factor. It represents how much electricity your home or business uses on an average day. You can usually find this on your electricity bill.
- Average Peak Sun Hours (hours/day): Also known as "solar insolation," this is the equivalent number of hours per day when solar irradiance averages 1,000 watts per square meter. It varies significantly by geographic location and time of year. For example, a location might have 4.5 peak sun hours, meaning the total solar energy received throughout the day is equivalent to 4.5 hours of full, direct sunlight.
- Individual Panel Wattage (Wp): This is the power output of a single solar panel under standard test conditions (STC). Common panel wattages range from 300W to 500W.
- System Loss Factor (%): No solar system is 100% efficient. Losses occur due to factors like temperature, wiring resistance, dust, shading, inverter efficiency, and degradation over time. A typical system loss factor ranges from 15% to 25%.
- Estimated System Cost per Watt ($/Wp): This is a general estimate of the total cost of a fully installed solar system (panels, inverter, racking, labor, etc.) divided by its total wattage. Prices vary widely based on location, system size, and component quality.
Battery Storage for Off-Grid or Backup Systems
For off-grid systems or grid-tied systems with battery backup, you'll need to consider:
- Desired Battery Autonomy (days): How many days you want your system to run solely on battery power without any sunlight (e.g., during cloudy weather).
- Battery Bank Voltage (V): The voltage of your battery bank (e.g., 12V, 24V, 48V). Higher voltages are generally more efficient for larger systems.
- Individual Battery Capacity (Ah): The amp-hour rating of a single battery.
Example Calculation
Let's say your home uses 15 kWh/day, your location gets 4.5 peak sun hours/day, you plan to use 400 Wp panels, and you estimate a 20% system loss. The estimated cost is $2.50/Wp. You also want 2 days of battery autonomy with a 48V battery bank using 200 Ah batteries.
- Total Daily Energy Needed (Wh): 15 kWh * 1000 = 15,000 Wh/day
- Total Panel Wattage Required (Wp): 15,000 Wh / (4.5 hours * (1 - 0.20)) = 15,000 Wh / (4.5 * 0.80) = 15,000 Wh / 3.6 = 4,167 Wp
- Number of Panels Needed: 4,167 Wp / 400 Wp/panel = 10.42 panels. Rounded up, you'd need 11 panels.
- Estimated System Cost: 4,167 Wp * $2.50/Wp = $10,417.50
- Required Battery Bank Capacity (Wh): 15,000 Wh/day * 2 days = 30,000 Wh
- Required Battery Bank Capacity (Ah): 30,000 Wh / 48V = 625 Ah
- Number of Batteries Needed: 625 Ah / 200 Ah/battery = 3.125 batteries. Rounded up, you'd need 4 batteries.
This calculator provides a useful estimate, but for precise planning, always consult with a professional solar installer who can conduct a detailed site assessment and provide an accurate quote.