Solar Calculator




So let's start with the technical details.

Solar energy is clean, renewable energy production. India is blessed with 300 days of clear sunshine. Solar fixes the energy costs, avoiding utility rate increases. The life of a solar power plant feature a 25 year output warranty. This system will produce free and reliable electricity for decades. As an investment in your factory, office building will enhance its value while delivering clean, quiet energy for you to use.

a. 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.

b. 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.

There are two basic components:

Solar array: Ten to Hundreds of kilowatts of solar panels, typically mounted on unused south facing roof space.

Inverter: Converts solar energy (DC) in AC to match utility power. Inverter output is connected to the Grid Panel.(Distribution Box). Priority is set for Solar Power & then for Grid Supply. So your maximum utilization of energy will be from Solar System.

The grid connect inverter will automatically shut itself off within a few milliseconds of a blackout, to avoid the potential of a dangerous “brown-out” in your facility and to prevent back feeding into the grid. Therefore even though you have a solar system during a blackout you will not have power available. If you want to keep on having electricity available during a blackout then you would need to have back up batteries installed as well, which will add to the cost of the system.

The factors to be considered are as follows:

a. 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

b. 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.

c. 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

d. 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.

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

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.

The inverter has a display that shows the cumulative energy produced by the solar array. Also we are providing monitoring system on your local PC. Detailed graphical analysis of system performance can be accessed from your local computer.

Yes. Additional solar panels can be added at any time to increase generating capability but you might have to upgrade to a larger inverter. Alternatively you could purchase an larger inverter when installing the system initially and then plan to add some extra solar panels later.

A solar rooftop plant has a lifespan of 25 years. Solar modules have been tested in the field showing small reductions in power output after 20 years, mostly because the glass surface becomes a bit dull and reflects more light. All our solar panels carry an output warranty of 25 years. The electronic components such as inverters, being the most sensitive, will last 10 -15 years.

Outright Purchase Solar Lease/PPA
Cost savings Levelised cost of solar is as low as ` 5/unit. Cheaper than both grid electricity and PPA model PPA’s are signed for 20 years at a price of about ` 7-8 /unit which is cheaper than grid electricity but higher than outright purchase.
Payback period Payback period – 5-6 years plus free electricity for a period of 20 years Requires long term payment and the owner pays up to 2-3 times more than the cost of rooftop system. Sometimes it requires end of term buy out contract, new contract or system removal fees
Upfront cost Solar PV systems have high upfront costs No upfront cost in solar lease agreement
Tax benefits/ capital subsidy Tax benefits/capital subsidy are available to home owner which makes system cheaper Tax benefits are availed by third party providing system on lease
Internal rate of return Rate of return is higher Rate of return is lower than in outright purchase

The solar photovoltaic(PV)modules are warranted for performance output. 90% of the rated PV module output is guaranteed for a period of 10 years and 80% of the PV module output is guaranteed for total period of 25 years. For optimal performance, weekly cleaning of solar panels should be done to avoid bird droppings and other dust.

Following benefits are available for grid-connected solar rooftop plant:

a. MNRE central financial assistance i.e 30% of the benchmark cost for selected categories

b. Accelerated depreciation for industrial and commercial buildings

c. Customs Duty and Excise Duty Exemption

d. 10 years tax holiday

e. Net metering

f. Provision of bank loans as a part of home loan/home improvement loan

g. Loan for system aggregators from Indian Renewable Energy Development Agency at concessional interest rate (9.9% to 10.75%)

h. Loans available up to Rs. 15 crore for renewable energy projects and upto Rs. 10 lakhs for individual loans under priority sector lending

When the levelised cost of power production from an alternative source of energy like solar becomes equal to or more than the power supplied from the grid, the energy source is considered to reach grid parity. Today solar is on its way to reach grid parity. The kind of fall observed in prices of photovoltaic module recently clearly suggest the lowering of capital cost investment in this sector thereby reducing the capital cost of project.

In a grid-tied solar PV system, electricity can flow through your meter in either direction, depending on the amount of electricity your system is producing and how much electricity you are using. When your solar PV system is producing more electricity than you need, the surplus is pushed back into the grid, spinning your meter backwards. When surplus is pushed back into the grid, one receives credit from the respective distribution licensee as mentioned in their regulations. Maharashtra has recently adopted the net metering policy and set guidelines to avail this benefit.

Under the MNRE implemented “Grid-connected Rooftop and Small Power Plants Programme”, CFA of 30% of benchmark cost is available for following categories:

a. All types of residential buildings

b. Institutional buildings like schools, health institutions, including medical colleges & hospitals (both public and private), R&D institutions etc

c. All government buildings

d. Social sector like community center, welfare homes, old age homes etc.

Note: Private, commercial and industrial buildings rooftops are not covered this subsidy

The system weighs approximately 27 to 30 kilograms per square meter (a 1KW system is approximately 10 square meters).

Rooftop solar power is much cheaper than power from diesel generators. Compared to solar power’s Rs.4.0-5/kWh, diesel generators generate power at about Rs. 16/kWh (a litre of diesel generates around 3-4 kWh). Diesel power can be even more expensive once other losses such as pilferage, evaporation, etc. are considered.

Typically, no; it might be possible in some cases based on factors such as the nature of the load, timing of load shedding, etc. but for many commercial/industrial units 100% replacement of diesel power with rooftop solar is unlikely, while partial replacement of diesel consumption is possible.

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.

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