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While you decide to install a solar power plant at your rooftop, it is important to select right size of solar PV system. Here are 5 key considerations which you should consider while deciding the solar PV system size for your home or in your commercial building as per your need.

CONSIDERATION 1: Check your monthly and annually electricity bill.

It is important to analyse your monthly and annual electricity consumption. If you check your monthly bill, then you should check your monthly bill for summer as well as winter. Typically, if your monthly electricity bill is of Rs 3000 in winter and Rs 6000 in summer, then it is good to go for 5 kW solar PV system. As if we consider the average electricity price somewhere around Rs 8/unit. In that case your monthly electricity consumption varies between 500 units to 1000 units depends on seasonal variations. Typically, 1 kW of solar plant produces about 4 units in a day. Hence, about 120 units in a month. Hence, a 5 kW system will be producing about 600 kWh/month.

CONSIDERATION 2: Check your daily power usage kWh/day.

If you have 1000 kWh/month consumption that means about 30-35 units/day of daily energy consumption. In that case, you can estimate your solar system PV size and number of panels with the following considerations. Please note that typically 1 kW of solar system produces about 4 units. Hence, you will need about 6-8 kW of PV system to meet your daily energy requirement.

CONSIDERATION 3: Check your daily solar radiation.

It is important to consider the solar radiation and daily sun hours. Typically, in India we get about 5-6 hours of direct sunlight on your roof. Though this direct sunlight reduces during winters. However, you get reasonably good solar exposure on your roof during summers. The direct sun exposure of your building will decide whether you are able to produce 4 units/day or 5 units/day on each kW of solar panel installation. Following formula can be useful to estimate your solar PV system kW requirement.

kWh per month / (Avg sunlight per day * 30) = kW solar system

CONSIDERATION 4: Check your grid power availability.

If you have an intermittent power supply and the grid power supply is not available between 5-6 hours in a day, then it is important to consider the solar PV system with energy storage. The solar PV system with energy storage is also known as Hybrid solar PV system. You can use this system to meet your power requirement. However, in the absence of grid electricity, the same system will be able to provide you power under the off-grid conditions. Though the hybrid power system cost will increase significantly as the battery cost/energy storage system cost is very high. However, it is equally important to consider the option of energy storage while you are deciding your solar PV system.

CONSIDERATION 5: Check how many solar panels can be installed on your roof.

It is important to access the size of roof as well. Though you may be having energy requirement which is met by 8 kW solar rooftop system. However, if the roof is not adequate to install about 25-30 solar panels on your roof then it is not possible to meet all your energy requirement through solar panels. Hence, part of your energy requirement can only be met by solar PV panels. Balance requirement shall be met by grid electricity.