Get your basics on installing solar panels right

Solar panels on roof and say goodbye to bills

Yes, you can. Solar panels (photovoltaic) on rooftops are the easiest way to get free-of-cost green energy. They convert sunlight to electricity, are practically maintenance free, and come with a life of more than 25 years.

Things You Will Need

Any space (rooftop, garden, balcony) which gets direct sunlight from sunrise to sunset – approximately 100 sq ft for 1 kW. Higher efficiency panels (=higher cost) require less area.

How Much Solar Power Do I Need?

The best way to determine how much Solar power you need is to check your electricity bill. The number of ‘units’ consumed in a month is the energy consumption in kilo-watt-hours (kWh). 1 unit = 1 kWh. You need to divide this by 30 to get the per day power consumption. Please note that power consumption is higher in summers (higher usage of air conditioners and fans) and lower in winters for most parts of India. We recommend using the summer numbers.

A 1 kW solar panel typically produces 4-5 units in a day depending on the amount of sunlight you get in your area. 1 kW solar setup (panels, batteries, inverter, controller) costs an average of INR 1 lac.

A typical 3 BHK house with five fans, one AC, one refrigerator, one light in each room would consume around 500 units a month. That means around 16 units a day. Solar panels of around 4 kW are necessary to go completely off the grid. Also, you can partially power from solar, with or without batteries too. Such a setup can start as low as INR 60,000 per kW. Covering the base load (minimum consumption) or day time load can be done with a no-battery system. You can also sell excess energy back to the grid and earn money if your state supports net metering. We will cover more on net metering and batteries later.

Few Things To Keep In Mind

Before you go solar, it is important to cut down on energy load by replacing inefficient appliances with BEE 5 star rated efficient appliances (inverter ACs, LED lights, 5 star fans, laptops/tablets instead of desktop). Generally, older appliances consume more power. For example, a new 5 star rated AC can consume around 40 percent less power than the 10 year old ones. This way you will require a smaller investment in terms of solar panels, and also save energy.

Alternatively, you can calculate the wattage of every appliance you use and want to be powered by solar. The best way to determine this is to check for labels mentioned in ‘watts’ on the appliances itself. Here is a rough estimate of power consumption of appliances:

Ceiling fan – 80 watts
Tube light – 40 watts
Incandescent bulb – 100 watts
CFL – 10-25 watts
LED – 5-18 watts
Refrigerator – 250 watts
Air conditioner (1.5 ton) – 1600 watts
TV – 150 watts
Electric iron – 750 watts
Laptop – 50 watts
Desktop PC – 300 watts
Washing machine – 400 watts
Microwave oven – 1000 watts
Induction cooker – 2000 watts
Mixer grinder – 750 watts
Water pump – 750 watts

Please note these are very average numbers. Efficient appliances can consume a lot less while non-efficient ones can consume much more. Power consumption multiplied by the number of hours you use in a day will give you the watt hours. Divided by 1000 = kWh or units.

Sounds confusing? You can use an online calculator or best stick to the electricity bill method. Solar power installers will definitely calculate it for you and give you the details.

Image source: Wikipedia Commons

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