Key Questions You Must Ask Before Installing Solar Power

You have taken the right decision to help save the environment by generating your own clean electricity through solar. We understand that if you are installing solar in your home for the very first time, then you may have many questions about it. We would like to give you the right information about installing solar in India. Below are some commonly asked questions and their answers:

What should be the size and configuration of my off-grid solar system?
When you are installing solar in your house you would want to know how big of a system do you really need. The answer to that depends on how much energy will your appliances use over a period of time.

The power consumption of appliance is generally given in Watts (e.g. an FL tube light consumes around 40 Watts power (this information can be found on the data sticker that most electrical items have). To calculate the energy you will use over time, just multiply the power consumption by the hours of intended use. The 40W tube light in this example, on for 4 hours, will take 40×4=160 Watthour (Wh), further if you have 2 such lights required to run for 4 and 3 hours respectively, the total energy consumption will be(40×4 = 160) + (40×3 = 120) = 280Wh. Repeat this for all the appliances you wish to use, and then add the results to establish total energy consumption.

Let's say that your electricity consumption is of 1500Wh. It is recommended that the size of your solar array should be at least 35% of daily energy consumption, preferably 40%. In this case, you should go for a solar panel of 1500×40%= 600Wp.

What about the size of solar inverter/PCU?
Solar PCU is a standalone unit which serves as an inverter and has an inbuilt solar charge controller. It is recommended that the size of inverter in off-grid installation should be at least 40% more than the total power of solar panels. So if you are installing solar panels of 600Wp, then your solar inverter should be 1.5kva.

How to calculate the size and capacity of battery
You need batteries to store the extra solar energy you generate which can be used later (in the absence of Sun). The size of battery depends on the energy usage during backup time that you would like from the batteries. Battery capacity should be at least 160% of the energy consumption. Let's say that your total load is 1500Wh
So you need minimum 1500×160% = 2400 Wh capacity. Means 12V/200Ah or 24V/100Ah battery.

It is advised to select capacity of battery approximately 1.25 times of the above calculation for reliable operation. In above mentioned example you can use 2nos. 12V/120Ah batteries.

What if I chose a grid-tie/on-grid system?
If you want a grid-tie solar system then capacity of grid tie system shall not be more than your average AC load. So if your average electricity requirement is 2000 watts, you would go for a grid-tie inverter of 2000 watts. 2kW capacity solar array and solar grid tie inverter can be use for this application.

How much rooftop space do I need?
Most of the solar panels are installed on rooftop. However, in some cases they can also be mounted on ground. You would need a shadow-free area of approx 12 sq metres to accommodate 1kWp solar panels. Please make sure that the area gets maximum sun light. Your solar installer will select the best angle for solar panels.

For how long will I be able to run my connected appliance on solar? How much electricity will it generate?
An offgrid 1KWp solar system can provide an average of 4 units (AC energy) electricity per day. While a grid tie system can provide an average 5 units per day.

How do I calculate solar savings?
Most of the times, the number 1 reason for installation solar at home in India is to save money - fair enough. Going solar really helps people who usually get very high electricity bills because they get to make their own electricity for free. Let's say that you have a 5kW system, then it will generate 20 units of electricity per day - 600 per month - 7200 per year. If 1 unit of electricity costs Rs 9 then it would cost Rs. 64,800. You would make Rs. 64,800 worth of electricity through solar - this is your savings.

Is there a subsidy that I can get from the government if I install solar?
Yes, some states in India do have subsidy schemes and some offer to buy the extra solar electricity that you make (through grid-tie systems). However, in reality very few people use subsidy because it requires too much paperwork and takes too much time. Our advice would be to forget about subsidies and select a solar system that gives you a good ROI. We have seen that some people recover the cost of installation in just 5 years!

After I install solar system do I need to worry about maintenance and service?
Solar panels are quite rough and tough and come with a warranty of 25 years. However, with time the solar power system (panels, inverter and battery) may get some technical problems. So it is very important that you buy your solar system from a reputed brand that offers good service. We discourage you from buying cheap Chinese solar products because they are very unreliable. When you are installing solar unit, think of it as an investment. Good investment will bring great returns.