Solar & Battery Sizing Calculator
Estimate the battery capacity, inverter size and solar panel capacity required for your home, office, shop or backup power system.
1. Enter Your Power Requirements
Enter the appliances or electrical loads you want to operate. Add each load, its power consumption, quantity and daily operating time.
2. Battery & Solar Settings
3. Solar Panel Settings
Your Estimated System Size
Recommended System
Solar & Battery Sizing Calculator
Choosing the correct solar panel, battery and inverter size starts with understanding how much electricity your appliances consume. This calculator estimates the solar array, battery capacity and inverter size needed for your electrical loads.
Enter your appliances, power consumption, quantity and operating hours. The calculator then estimates your daily energy requirement and recommends a suitable system size based on your selected battery type, system voltage, solar hours and panel wattage.
How to Calculate Solar Panel Size
Solar panel capacity depends mainly on your daily energy consumption and available peak sunlight.
For example, if your home uses 6,000Wh per day, receives 5 peak sun hours and the overall solar system efficiency is estimated at 80%:
A practical system would therefore need approximately 1.5kW of solar capacity before considering additional design margin.
How Many Solar Panels Do I Need?
Once the required solar capacity is calculated, divide it by the wattage of the solar panel you plan to use.
The result should be rounded up to the next whole panel because you cannot install 3.4 panels, despite humanity's continuing enthusiasm for awkward compromises.
How to Calculate Battery Capacity for Solar
Battery sizing depends on how much energy you need during the period when solar power is unavailable or insufficient.
Lithium batteries generally allow a greater portion of their nominal capacity to be used than traditional lead-acid batteries. The actual usable capacity depends on battery chemistry, manufacturer specifications, temperature, battery age and operating conditions.
Ah vs Wh for Solar Batteries
Battery capacity is commonly shown in amp-hours (Ah), while energy is measured in watt-hours (Wh).
For example, a 48V 100Ah battery has a nominal energy capacity of approximately 4,800Wh, or 4.8kWh.
What Size Inverter Do I Need?
Inverter capacity should be large enough to handle the appliances that may operate simultaneously. A margin should normally be allowed above the calculated running load.
Appliances containing motors, such as refrigerators, pumps, air conditioners and some washing machines, can require substantially more power when starting. The inverter must therefore have adequate surge capacity as well as a suitable continuous power rating.
Why 48V Battery Systems Are Common for Larger Solar Systems
Higher battery voltage allows the same power to be delivered with lower electrical current. This can make larger battery and inverter systems more practical.
Small systems may use 12V or 24V, while larger systems often use 48V. The battery voltage must always be compatible with the selected inverter and battery configuration.
Solar Battery Sizing Example
Suppose your appliances require 6kWh of energy per day and you want enough battery capacity to cover approximately one day of backup.
With a LiFePO4 battery using an assumed 90% usable capacity and a 90% inverter efficiency:
This means approximately 7.4kWh of nominal battery energy would be required under these assumptions.
Solar & Battery Sizing for Home Backup
A complete home backup system normally consists of three major parts: solar panels, a battery and an inverter.
- Solar panels: Generate electrical energy during sunlight.
- Battery: Stores energy for later use.
- Inverter: Converts battery DC power into AC power for household appliances.
The correct system size depends on whether the system is designed for daytime solar use, nighttime backup, load shedding, off-grid operation or whole-home backup.
Solar Panel Size for a Home
There is no single solar panel size that is correct for every home. A household using a few fans, lights and a refrigerator will have very different requirements from a home using air conditioners, electric water pumps, washing machines and other high-power appliances.
Start with your actual electrical loads and daily energy consumption rather than choosing a solar system based only on the size of your home.
Important Factors That Affect Solar & Battery Sizing
- Appliance power consumption
- Daily operating hours
- Peak simultaneous load
- Motor startup surge
- Battery chemistry
- Battery usable depth of discharge
- Inverter efficiency
- Solar panel efficiency
- Peak sunlight hours
- Panel orientation and shading
- Temperature
- Wiring and system losses
- Required backup duration
Frequently Asked Questions
How many solar panels do I need for my home?
It depends on your daily electricity consumption, peak sunlight hours, system efficiency and panel wattage. Enter your loads above to estimate the required solar capacity and number of panels.
How much battery capacity do I need for solar?
Battery capacity depends on how much energy you want to store and how long you need backup power. Battery chemistry and usable depth of discharge also affect the required nominal capacity.
What size inverter do I need for solar?
The inverter should be sized according to the maximum appliances that may operate simultaneously, with additional capacity for startup loads and system margin.
Is a 48V solar battery better than a 12V battery?
Higher-voltage battery systems can be more practical for larger power requirements because they operate at lower current for the same power. The correct voltage depends on the complete system design and inverter.
How many watts of solar do I need?
A simplified calculation is daily energy divided by peak sun hours and solar system efficiency. Actual solar production varies according to weather, season, shading, panel orientation and system losses.
Is this calculator suitable for an actual solar installation?
It is intended for preliminary planning and estimation. A qualified solar installer should verify the final system design, inverter specifications, battery configuration, protection equipment, cable sizing and installation requirements.
Solar & Battery Sizing Calculator
Estimate the battery capacity, inverter size and solar panel capacity required for your home, office, shop or backup power system.
1. Enter Your Power Requirements
Enter the appliances or electrical loads you want to operate. Add each load, its power consumption, quantity and daily operating time.
2. Battery & Solar Settings
3. Solar Panel Settings
Your Estimated System Size
Recommended System
Solar & Battery Sizing Calculator
Choosing the correct solar panel, battery and inverter size starts with understanding how much electricity your appliances consume. This calculator estimates the solar array, battery capacity and inverter size needed for your electrical loads.
Enter your appliances, power consumption, quantity and operating hours. The calculator then estimates your daily energy requirement and recommends a suitable system size based on your selected battery type, system voltage, solar hours and panel wattage.
How to Calculate Solar Panel Size
Solar panel capacity depends mainly on your daily energy consumption and available peak sunlight.
For example, if your home uses 6,000Wh per day, receives 5 peak sun hours and the overall solar system efficiency is estimated at 80%:
A practical system would therefore need approximately 1.5kW of solar capacity before considering additional design margin.
How Many Solar Panels Do I Need?
Once the required solar capacity is calculated, divide it by the wattage of the solar panel you plan to use.
The result should be rounded up to the next whole panel because you cannot install 3.4 panels, despite humanity's continuing enthusiasm for awkward compromises.
How to Calculate Battery Capacity for Solar
Battery sizing depends on how much energy you need during the period when solar power is unavailable or insufficient.
Lithium batteries generally allow a greater portion of their nominal capacity to be used than traditional lead-acid batteries. The actual usable capacity depends on battery chemistry, manufacturer specifications, temperature, battery age and operating conditions.
Ah vs Wh for Solar Batteries
Battery capacity is commonly shown in amp-hours (Ah), while energy is measured in watt-hours (Wh).
For example, a 48V 100Ah battery has a nominal energy capacity of approximately 4,800Wh, or 4.8kWh.
What Size Inverter Do I Need?
Inverter capacity should be large enough to handle the appliances that may operate simultaneously. A margin should normally be allowed above the calculated running load.
Appliances containing motors, such as refrigerators, pumps, air conditioners and some washing machines, can require substantially more power when starting. The inverter must therefore have adequate surge capacity as well as a suitable continuous power rating.
Why 48V Battery Systems Are Common for Larger Solar Systems
Higher battery voltage allows the same power to be delivered with lower electrical current. This can make larger battery and inverter systems more practical.
Small systems may use 12V or 24V, while larger systems often use 48V. The battery voltage must always be compatible with the selected inverter and battery configuration.
Solar Battery Sizing Example
Suppose your appliances require 6kWh of energy per day and you want enough battery capacity to cover approximately one day of backup.
With a LiFePO4 battery using an assumed 90% usable capacity and a 90% inverter efficiency:
This means approximately 7.4kWh of nominal battery energy would be required under these assumptions.
Solar & Battery Sizing for Home Backup
A complete home backup system normally consists of three major parts: solar panels, a battery and an inverter.
- Solar panels: Generate electrical energy during sunlight.
- Battery: Stores energy for later use.
- Inverter: Converts battery DC power into AC power for household appliances.
The correct system size depends on whether the system is designed for daytime solar use, nighttime backup, load shedding, off-grid operation or whole-home backup.
Solar Panel Size for a Home
There is no single solar panel size that is correct for every home. A household using a few fans, lights and a refrigerator will have very different requirements from a home using air conditioners, electric water pumps, washing machines and other high-power appliances.
Start with your actual electrical loads and daily energy consumption rather than choosing a solar system based only on the size of your home.
Important Factors That Affect Solar & Battery Sizing
- Appliance power consumption
- Daily operating hours
- Peak simultaneous load
- Motor startup surge
- Battery chemistry
- Battery usable depth of discharge
- Inverter efficiency
- Solar panel efficiency
- Peak sunlight hours
- Panel orientation and shading
- Temperature
- Wiring and system losses
- Required backup duration
Frequently Asked Questions
How many solar panels do I need for my home?
It depends on your daily electricity consumption, peak sunlight hours, system efficiency and panel wattage. Enter your loads above to estimate the required solar capacity and number of panels.
How much battery capacity do I need for solar?
Battery capacity depends on how much energy you want to store and how long you need backup power. Battery chemistry and usable depth of discharge also affect the required nominal capacity.
What size inverter do I need for solar?
The inverter should be sized according to the maximum appliances that may operate simultaneously, with additional capacity for startup loads and system margin.
Is a 48V solar battery better than a 12V battery?
Higher-voltage battery systems can be more practical for larger power requirements because they operate at lower current for the same power. The correct voltage depends on the complete system design and inverter.
How many watts of solar do I need?
A simplified calculation is daily energy divided by peak sun hours and solar system efficiency. Actual solar production varies according to weather, season, shading, panel orientation and system losses.
Is this calculator suitable for an actual solar installation?
It is intended for preliminary planning and estimation. A qualified solar installer should verify the final system design, inverter specifications, battery configuration, protection equipment, cable sizing and installation requirements.