40 GW from rooftop PV by 2022 still a myth!

15th Oct 17  

Solar rooftop potential

India has played an active role when it comes to deployment of renewable energy sources. It has played a leading role in forming the International Solar Alliance (ISA)with the prime objective to focus on utilization of solar energy. Additionally, India itself has set an ambitious target of 100 GW from solar power by 2022 which is divided into 60 GW of utility scale plants and 40 GW of rooftop scale plants. While the uptake of utility scale solar power plants has increased, the solar rooftop market whose installed capacity stands at mere 1,396 MW at the end of March 2017 is yet to see the light of the day.

There has been significant number of study which gives out the rooftop potential for the country/state/city. The data from such studies show that the potential of rooftop is huge. The study carried out by Greenpeace and Bridge to India for the city of Delhi(Figure 1) estimates that the city’s total potential is 2.5 GW. Another study carried out by IIT Bombay and Bridge to India for the city of Mumbai (Figure 2) (only Greater Mumbai) estimates that the city’s total potential is 1.7 GW. It is hence clear that the metro cities (and the entire country) have huge potential for solar rooftop power plants.

Figure 1: Estimated rooftop capacity of Delhi city

Figure 2: Estimated rooftop capacity of (Greater) Mumbai city


While there have been many mentioned common advantages of utilizing solar energy, few advantages of using solar rooftop system are presented below:

  • Reduction in Transmission & Distribution (T & D) losses : The current policy for solar energy exempts the applicability of Transmission and Wheeling losses for Interstate and (few) Intrastate transactions for solar energy generators. Hence currently the central/state utilities have to bear such losses. Based on our estimates, with the installation of 40 GW of rooftop solar in 2022, the central/state utilities would avoid T&D losses equivalent to 8,000 MU of energy. Such energy saving would be advantageous for the country as a whole and such saved energy can be routed to un-electrified villages.
  • Savings to Distribution Company (Discom): The Discom is known to be the weakest link in the entire value chain of power supply. While schemes like UDAY have been launched by the Govt. of India, the Discom (except few) still remains financially stranded. These utilities have a mandatory obligation to supply power meaning at many times a day when they are short of power; they have to buy power from the energy exchange market (spot power). Such power is highly variable in nature and comes at hefty cost which adds financial burden to the already stranded Discom. Installing adequate solar rooftop would lead to lower power requirement and the excess energy (from solar rooftop plant) (if any) are bought at a rate significantly lower than the spot market leading to adequate savings to Discom.
  • Increase in tail end voltage:The supply at our homes happens at 220/230 V (in case of single phase connection) or 440 V (in case of three phase connection). However it is a lesser known fact that these supply voltages are at the sending end sub-station of Discom and the supply voltage at our homes is less due to losses. Solar energy power plants are form of distributed generation plants which would boost the tail end voltage and also the quality of power supplied.
  • Long termreliability of power supply: There has always been surge in energy prices. This can be manifested from the previous tariff orders of various utilities. It is expected that the energy prices shall strongly rise in the near future. Solar power plants which has a fixed per unit energy price (for 25 years) can come to the rescue of the consumers.


Few issues that act as a barrier in implementing solar rooftop systems are presented below:

  • Resistance from Discom: The consumer, in order to enjoy benefits on net metering has to obtain a grid connectivity certificate (essentially a NOC) from Discom (which still owns the grid). Discomas a service provider needs to have adequate power supplier (in form of Power Purchase Agreement (PPA)) in order to meet their demands. There are few PPA’s which are of long term in nature (meaning they are signed for 25 years). Hence, by installing solar rooftop system, a consumer would draw certain amount of his requirement from solar power plant leading to loss of revenue to Discom. The Discom fearing to the loss of revenue delays or denies (in some cases) the grid connectivity certificate citing various (bizarre) technical reasons.
  • Frequent power cuts:The inverter currently available in market come with anti-islanding feature. This feature enables the inverter to disconnect the entire system with the grid and would stop supplying power to the load in case of power cut. This prevents the reverse flow of power to grid which gives added protection to person(s) working on the grid (if there is breakdown). However such power cuts (if frequent) may lead to reduction of energy generation and hence the loss in revenue.
  • Operation and Maintenance (O and M) of power plant:While it may not seem an important activity after installing a solar power plant, O & M has a significant impact on plant performance. The fact that solar power plants need cleaning is well known. But the plant also needs regular maintenance for checking the inverters and the Balance of System (BoS). While this is done in large scale plants, the small scale rooftop power plants tend to ignore this leading to loss in energy generated and hence the revenue in log term.
  • Myth on transformer capacity limitation:The transformer acts as an important link between the Discom and the consumer. It converts the incoming high voltage power to usable (at homes) low voltage power. It is a general notion that the transformer would get fully affected if we feed in reverse power (from solar power plant) which is not true. It can take a reverse power flow at a safe limit (20% of rated power capacity of transformer) and the same is adopted by various utilities.
  • Other factors: The reduced uptake of rooftop may be directly linked to the lack of awareness amongst consumers. There are special portals for solar energy set up byfew government bodies (like by Surat Municipal Corporation) which would lead to attitude shift with passing time. It is also important to note that the time lag in commissioning the plant to receiving the subsidy is significant.

While there are issues, we at Waaree Energies Ltd. believe in efficient and optimal utilization of rooftop space for installing solar power plants. Waaree has just commissioned a 2.3 MW of solar rooftop plant in over 12 stations in Mumbai metro without any accidents.India currently contains 300 million houses, but not all of them can hold the traditional solar PV modules (i.e. some of them require frameless and/or flexible modules). There are only few leading manufactures in the world capable of producing such modules and Waaree is one of them. Our flexible Merlin modules (Figure 3) comes with a state of art technology which enables maximum flexibility and can deliver performance even if there are micro cracks (and even cracks) in solar cell. These modules are already tested on various transport vehicles and have been found to work perfectly. They can be customized according to the consumer requirements based on their area or power.

Figure 3: Waaree Merlin modules and its testing (on a truck)

Let us all pledge to make solar energy the primary source of energy in the near future.