Frequently Asked Questions ?

How Can We Get Electricity From the SUN?

When certain semiconducting materials, such as certain kinds of silicon, are exposed to sunlight, they release small amounts of electricity. This process is known as the photoelectric effect. The photoelectric effect refers to the emission, or ejection, of electrons from the surface of a metal in response to light. It is the basic physical process in which a solar electric (OR) photovoltaic (PV) cell converts sunlight to electricity.

Sunlight is made up of photons, or particles of solar energy. Photons contain various amounts of energy, corresponding to the different wavelengths of the solar spectrum. When photons strike a PV cell, they may be reflected or absorbed, or they may pass right through. Only the absorbed photons generate electricity. When this happens, the energy of the photon is transferred to an electron in an atom of the PV cell (which is actually a semiconductor).

With it's new found energy, the electron escapes from its normal position in an atom of the semiconductor material and becomes part of the current in an electrical circuit. By leaving its position, the electron causes a hole to form. Special electrical properties of the PV cell-a built-in electric field-provide the voltage needed to drive the current through an external load (such as a light bulb).

What are the different types of solar power systems.?
i) Grid - Tied System

In this type of system, our system will work in conjunction with the grid. Solar power is the primary source of electricity. The electrical grid supplies power during night and cloudy days. The inverter shuts down the system during power failure.

ii) Off - Grid System

In this type of system, battery backup or diesel generator is present. The system works independent of the conventional grid. Using the inverter, the battery backup or diesel generator powers the load during night and cloudy days.

What are the factors to be considered prior to installation of a solar rooftop plant?
The factors to be considered are as follows:
i) Location

Your location determines the amount of solar insolation (sunlight falling on the panel per day). Overall, the location of the rooftop is by far the most important factor that determines the solar power plant output. Location determines the DNI (Direct Normal Irradiance). DNI at a location is the amount of solar energy falling per sqm per day at that location. India has good solar DNI

ii) Orientation

A system with solar panels facing in a southerly direction will generate far more than one with a northerly aspect. However, east/west installations can be a good option depending on the installation scenario.

iii) Panel Efficiency

Efficiency of the panel is calculated as ratio of capacity of the panel (kWp) with respect to the size (area) of the panel (m2), expressed as a percentage. The efficiency of the panels matters where the rooftop space is limited. As the lower efficiency panels occupy a greater area than higher efficiency panels, we will be able to install fewer panels in the same size roof. Fewer panels mean lower plant capacity, and therefore lower power output from the plant

iv) Ambient Temperature

Solar panel temperature is an often ignored but critical parameter in a hot country like India. Though it might seem counter-intuitive, solar PV panels generate less power in very hot summers as the heat reduces their efficiency (the voltage reduces). In Chennai, the month of January delivers better output than May.

What are the savings from installing a solar rooftop palnt?
System size 50 kWp 100 kWp 200 kWp 300 kWp 500 kWp
Area required (sq. feet) 5000 10000 20000 30000 50000
Annual generation 75,000 1,50,000 3,00,000 4,50,000 7,50,000
Yearly savings @ Rs. 11.15/unit 8,36,250 16,72,500 33,45,000 50,17,500 83,62,500
Yearly CO2 emissions avoided(kg.) 87,390 1,74,780 3,49,570 4,48,950 7,48,250
Is there any Maintenance Involved?

With an grid connected system, there is very little maintenance required. Electronic components should be maintenance free. Weekly cleaning of solar panels is recommended for optimum output.

How Big a Solar Energy System Do I Need?

The size of solar system you need depends on several factors such as how much electricity or hot water or space heat you use, how, the size of your roof, and how much you're willing to invest. Also, do you want the system to supply your complete energy usage or to supplant a portion of your higher cost energy usage? You can contact a system designer/installer to determine what type of system would suit your needs.

What Happens in Rainy Season & in the Night Time ?

Solar energy does vary throughout the year. In practice, grid-tie system owners don't usually worry as rainy season months have low production. We calculate annual energy production estimate on 300 sunny days. Solar Grid Tied System will not work in the night because Solar Modules need sunlight to produce power.