India produces its most of electricity through coal power plants and hydropower plants. Electricity produced through sources is getting expensive by each passing day. India produces its one-third of total electricity through coal and consequently harmful to the environment. Time had arrived we must think about the renewable source of energy. Installing rooftop system can help in great extent.
The government of India is promoting the rooftop solar system under Jawaharlal Nehru National solar Mission through Ministry of New and Renewable Energy (MNRE).
Many people have started feeling the need of installing the rooftop solar system for home, office and residential complex. Turning your home into a mini power plant can save a good sum of money on the electric bill. If your are one of them, but don’t know where to start?
In this article, we will guide how to install rooftop solar system.
Calculate your daily electricity consumption
First of all, you need to calculate your daily electricity consumption. It would help you to estimate the capacity of the solar project needed.
You can easily calculate it by your monthly electricity bill. Find out electricity consumed in the whole month and divide it by the number of days in that month. Repeat the process for last 4-6 months electricity bills to be more accurate.
lat’s take it 300 units (kWh) in a month.
The daily consumption would be 300/30=10 kWh. Now you know that you need a system which can generate at least 10 kWh electricity per day.
1 kW solar PV can produce 4-5 kWh electricity in a normal sunny day. On an average it could be taken as 4 units/day, therefore you will need to install 3 kW Solar PV to generate 12-15 kWh electricity per day.
Types of solar panels
Based on solar cell solar PV can be devided in 2 catogories:
How to select type of rooftop system?
There are 2 types of rooftop systems available.
1. On-grid rooftop system
On-grid rooftop system is connects to grid supply via net metering.
- Extra electricity transmitted to grid supply.
- You can earn money by selling surplus electricity.
- Installation and maintenance cost is relatively low.
- You can avail govt subsidy up to 30% on total installation cost.
- This system depends on grid connectivity if there is outage in power supply it would not generate electricity.
- No backup for Night.
2. Off-grid rooftop system
Off-grid system has its own battery bank to store electricity.
- It is a standalone system so can work without grid connection.
- Reliability: Electricity stored in battery bank can be utilized in night and cloudy day when sun is not available.
- Installation cost is relatively more due to additional cost of battery bank.
- Need extra space to install battery bank.
How to select solar inverter?
Solar inverter changes direct current (DC) from the panel into alternating current (AC) that your appliances can use, So the inveter is crucial component in solar PV system.
You can convert your normal power inverter to a solar inverter with the help of a charge controller. But there is a limitation with this system: You can’t use it for large rooftop systems.
Solar inverter capacity must be paired with solar PV capacity. If are planning to install a 3 kW system, Inverter must have 3 kW rating.
Select mounting structure and installation space
With crystalline panels, you have three options for location: Mounting the panels on your roof, on the ground. Most people think that a roof mount is the most convenient and aesthetically pleasing, but there are many reasons that people choose other options: if your roof is small, unstable, or in the shade. If you have enough open space, a ground mount may be better. Sizing of solar panels depends upon the efficiency of PV, more the efficiency of PV less the space required.
Standard size of panels are: 100w, 150w, 200w,250w, 280, 300w and 315w.
Efficiency of solar panels varies from 10%- 18% furthermore efficiency depend on Standard size of a solar panel. It is recommended to choose solar panel with efficiency of 12% therefore, a 1 kw project would need 100 sq ft area with this 12% efficiency.
(Source: solar PV sizing information on energysavers.gov).
Though the initial investment for a solar rooftop system is high, the return on investment has become increasingly attractive with the increase in prices of conventional energy. The payback period depends on the utilization, site of installation and fuel replaced. Although chines solar cell is cheaper, life is exceptionally low. MNRE issues the strict guidelines and monitors quality of MNRE approved products, therefore it is recommended to buy MNRE approved manufacture/supplier product. The expected life of solar rooftop is considered up to 25-35 years.