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Frequently Asked Questions

1. Introduction

A solar power plant using photovoltaics is different from the heat/thermal power plant used to heat water, steam or generate power. This is using semiconductor solar cells, soldered together to form a solar module generally of the size of 230 to 300W each for commercial use in roof top/ground mounted plants. Multiple solar modules are strung together in a series to get required voltage and many such strings are connected in parallel to get required current. The output is Direct Current (DC) which is then converted by an inverter into Alternating Current (AC), what we get from grid at home, office, factories.

The output of inverter is fed direct if it is 230/415V 3 phase or increased to 11-33-66KV as the case may be using transformers. A meter is generally available in each inverter, but the payments are done by utiity approved calibrated meters.
Usually this is directly fed into the grid for local consumption or exporting excess into the grid for net metering (bill = import-export). Where these is no local load, the whole of energy generated is sold to Government utilities or 3rd parties at a predetermined Power Purchase Agreement (PPA) rate. PPAs with government is generally signed for 20-25 years, often at a fixed rate.

2. Site
2.1. How much land is required to setup a solar power generation Unit?
Ground mounted: 1 MW power plant setup is around 4.5-5 acres for Crystalline/CdTe/CIGS technology and around 6.5-7.5 acres for amorphous Si Thin-Film technology. This is only a rough benchmark and may vary based on technology and efficiency of panels.
Rooftop: 1KW requires 100sq ft if flat surface, 75-85 sq ft if tilted in south (preferred) or east west (2nd best) orientation

2.2. What is the life-time of a typical Solar Power plant?
The useful life of a typical Solar Power plant is considered to be 25 years. This is the duration for which long-term PPAs are signed and financial models are built. However, Solar Power plants can run beyond 25 years while producing a lower output. Many Solar Panel manufacturers guarantee an output of 90% at the end of 10 years and 80% at the end of 25 years.

3. Generation
3.1. What would be the total project generation?
Most parts of India have 300 sunny days and 5-5.5KWHr/m2/day solar radiation on horizontal surface. With optimum south facing tilt (= latitude of location) it generates approx.1500 units/KW or 15Lakhs/MW. Detailed engineering design will give exact estimates. NASA data for average of over last 50+ years for solar radiation and ambient temperature is used for estimation, using software like PV Syst,
For east west roofs and depending on exact tilt etc., it may be lower by 3-7 % in most parts of Maharashtra.

4. Cost
4.1. What would be the total project cost excluding the cost of land?

Make sure the cost is considered per KW/MW DC (or KW/MW peak). Total project cost per MWpeak=MWp (as is called for MWDC) would be in the range of Rs.5.5 Crores-Rs.7 Crores depending on the kind of technology you are using, whether or not you are using tracking systems, soil, wind, voltage of power evacuation, scope (within battery limit, land, transmission lines, bays, Govt. fees and liaison) the kind of EPC Contractor you choose for power plant system etc. CERC recently announced the benchmark tariff for setup of Solar PV and Thermal Plants in India. {It is Rs.5 crore/MW for PV now!!}


Approx. land cost (barren) is < Rs.5-6 Lakhs/acre
Transmission line may be extra at Rs.6-15Lakhs/km dependent on voltage (11-33KV) and type of structure single or double pole and Right of Way (RoW) costs.

For roof top: it is typically Rs.50-70,000/KW

Q: [What is a Lakh (also called Lac) and Crore in India?]
A: [Lakh is 0.10 million and Crore is 10 million, so 100 Lakhs = 1 Crore - we love to be different! We invented the Zero! :)]

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