If you’re considering installing solar panels, batteries, and inverters, you may wonder how to determine the appropriate capacity for these components. Drawing from our practical experience, the guide below can assist you in making informed decisions.

How to Calculate Your Solar Panel, Battery & Inverter

How do I calculate how many solar panels I need?

Step 1: Load Calculation

To calculate the load, it’s advisable to utilize a high-quality clamp meter. Let’s assume we’re using a clamp meter supporting 600A for this calculation. With this tool, you can determine the power consumption of various settings such as homes, offices, shops, schools, medical clinics, and petrol pumps. Follow these steps to calculate power consumption:

Activate all appliances.
Utilize the clamp meter on the phase wire of the electric meter.
The clamp meter displays power consumption in amps (e.g., 5A, 10A, 20A, etc.).
As the Indian grid voltage range is typically between 220V-240V, ensure to check the voltage using the clamp meter.
Load Calculation = 220V * 5A
= 1100W

Step 2: Backup Time

After determining power consumption, assess how many hours you may need to run appliances during a power cut. For instance, if you require 4 to 5 hours:

Battery Storage = Total Load * Backup Time
= 1100W * 4 hrs.
= 4400W

Step 3: Battery Capacity

Based on the required battery storage, consider the available battery technologies in India – lead-acid and lithium batteries. For lead-acid batteries, the popular 150Ah battery stores 1300 Watts each. Therefore:

Battery Capacity = Required Battery Storage / Battery Storage
= 4400W / 1300W
= 4 Batteries
Typically, 4 batteries of 150Ah come in 48V configurations.
For lithium batteries, a single 5kWh, 48V battery suffices.

Step 4: Inverter Capacity

With the battery capacity and voltage determined, calculate the required inverter capacity. In simple terms, for a 48V & 5kW battery system:
Inverter Capacity = Load + Load * 20%
= 1100W + 1100W * 20%
= 1100W + 220W
= 1320W
Therefore, you require approximately a 1.3kW inverter capacity.

Step 5: Solar Panel Capacity

Lastly, compute the solar panel capacity. Remember, solar panels generate DC voltage ranging from 22V to 50V. Hence:
Solar Panel Capacity = 3 * Battery Capacity
= 3 * 600Ah
= 1800Watt

This implies you need a 1.8kW capacity of solar panels, and the highest wattage available in India is around 540W. Opting for these solar panels, you’ll require approximately 4 units to charge your battery and power your home loads efficiently.