Frequently Asked Questions (FAQs)

What is a Solar Roof-top System?

In a solar rooftop system, the solar panels are installed in the roof of any residential, commercial, institutional and industrial buildings. The following are the types:

  1. Solar Rooftop System with storage facility using battery. These systems are suited to remote locations where a grid connection is not available, i.e, when there will be no continuous power supply in the grid. The battery bank is sized to provide a certain number of days of storage in the installation. These systems store the electricity produced by conversion in batteries and utilize the stored energy by converting it back to AC as and when required. The reduction in battery prices over the years has further brought the system cost down.
  2. Grid Connected Solar Rooftop System - These systems have no storage other than the grid itself. Any excess electricity generated from the solar system is fed back into the grid. At night or during times, the installation draws power from the grid. These systems are designed to work in conjunction with the grid or simply put your electricity supply. The electricity you generate using this system is fed back to the grid. A net meter is installed along with this system to keep track of the electricity consumed by you versus what you generated and fed back to the grid resulting in savings which gets reflected in the bill.
  3. Grid-Connected – Hybrid (Grid-tied with Storage) – These systems are grid-connected, but also have some storage capacity by way of a small battery bank. They provide some measure of continuity when the grid goes down at the same time as there is not sufficient solar input.


What is a Solar PV (Photovoltaic) system and how does it work?

PV, short for Photovoltaic, derives its name from the process of converting light ('photo') directly into electricity (‘voltaic’). “Photovoltaic” is composite of two words. “Photo” means Light. “Voltaic” means producing Electricity. The term “photovoltaic” taken from Greek. Phos meaning “Light” and the name of Italian Physicist-Volta, after whom the volt (and consequently voltage) are named. The term “Photovoltaic” means producing electricity in the presence of Light. When sunlight is used, the relevant term is “Solar photovoltaic. A photovoltaic (PV) cell is also called as a Solar cell, which is a basic building block, is a device that converts sunlight into electricity.

A PV system is made up of different components. These include PV modules (groups of PV cells), which are commonly called PV panels; one or more batteries; a charge regulator or controller for a stand-alone system; an inverter for a utility- grid-connected system and when alternating current (ac) rather than direct current (dc) is required; wiring; and mounting hardware or a framework. Many cells put together are known as a module, and many modules assembled together to form an array. A PV system will consist of an array of modules generating DC electricity, an inverter (which converts D.C energy into A.C. energy) can be stored in battery storage banks or fed into the Electricity Grid.

Simply put, a Solar PV system is a power station that generates electricity from sunlight. The main components of a Solar PV system are:

  • Solar Panels/Modules:Solar panels consist of a group of small cells made from semiconductor material. When the sun’s light falls on the modules, it excites the electrons, thereby creating direct current (DC).
  • Storage Battery:The best use of solar energy is to consume it while it is being generated. If the requirement is to store this power and consume it in the non-sunny hours, then solar energy can be stored in batteries for later consumption
  • Solar Inverter: The DC electricity goes into an inverter that converts it into alternating current (AC). We use AC for running our household or office or factory equipment.

Solar Modules and Inverters are the main components of a solar power system and the constitute 70% of the project cost.


What is the lifespan of a PV system?

PV systems are currently considered to have at least a 25 years lifespan. Most panel manufacturers give warranty of 25 years, however there have been plants in operations for 40 years as well. PV modules are covered with a long term performance guarantee (usually 10 years with less than 10% decrease and 20 years with less than 20%) by all the most important manufacturers. Guarantees for electronic components such as UPS can also be extended for several years beyond standard terms. The Inverter with a guaranteed period of 5 years of performance is given. ESCOM will sign a Power Purchase Agreement (PPA) with Solar rooftop PV generator which will be in force for 25 years.


What is a solar panel all about?

A solar panel comprise of multiple PV (photo voltaic) cells that convert sunshine to electricity. Two types of PV Panels are there - while one comprise of "Polycrystalline Cells", the other one contains "Monocrystalline Cells". Polycrystalline cells are effectively a slice cut from a block of silicon, consisting of a large number of crystals. They have a speckled reflective appearance and are very thick. They are less expensive to produce and more suited for Indian conditions. Monocrystalline cells are much thinner and have a smoother feel to them. They are costlier to produce as compared to its polycrystalline counterpart. Based on the area available for solar installation, the required capacity of solar panels can be calculated. Call our solar expert to know your solar potential and get your solar journey started.


My electricity bill is huge, can I do something about it? How much electricity bill will I save when I use Solar?

Choose an On-Grid solar power system. These systems are designed to work in conjunction with the grid or simply put your electricity supply. The electricity you generate using this system is fed back to the grid. A net meter is installed along with this system to keep track of the electricity consumed by you versus what you generated and fed back to the grid resulting in savings which gets reflected in the bill. But keep in mind that it does not work when the grid is down, so if power back up is your objective, go for an off-grid solar solution.

The electricity bill you save is proportional to the capacity of the solar panel installed. In tropical country like India, we can expect average 4-5 hours of good sunlight for about 300 days in a year. A 1000 Wp panel installed on a South facing roof, will generate about 4-5 units per day on a sunny day. However, the energy generation depends upon the weather conditions and reduces for an East or West facing roof.


How much PV panel should I connect? How to know the solar installation size for my home?

It depends on the extent of power you want to generate. Contact us to provide consultancy regarding the same. Solar PV system can be used to power your entire home’s electrical systems, including lights, cooling systems, geysers, water pumps, refrigerator and other appliances. The best way to do it is to call a professional like PlasmaSolar llp. to help you out as there are many aspects and methodologies which needs to be taken into account before one arrives at the recommended system size for a particular site. Therefore it is advised to book a site survey with us and let our solar expert inspect your roof to suggest the best possible solution for you.


What is a Solar Rooftop System with Storage facility?

Such rooftop system has battery as storage facility. The solar electricity is stored in the battery and can be utilized during night also when the sun is not available.


I have power cut issue, which type of solar solution should I go for?

Go for Off-grid solar power systems. These systems store the electricity produced by conversion in batteries and utilise the stored energy by converting it back to AC so that you can keep running you appliances during power cuts. It's a boon if you are living or planning to live in an area with no mains connectivity. The reduction in battery prices over the years has further brought the system cost down.


Why is proper installation important? What benefit could a brand deliver as compared to local installer?

Installation by a trained technician is very important. There are many details like the quality of input & output wiring, reverse supply of AC voltage on the output, proper safety Earth, polarity of wiring, routing and casing of the PV cable etc. which has to be done as per standards. Ease of maintenance in case of a breakdown is also an important consideration. Good installation ensures trouble free and long life. Hence, get installed only by a trained technician.

With a multitude of solar installers available, defining the parameters for choosing the right one is a tough decision. Right from solar panels, inverters to the services offered by your installer like mounting the structure and other necessary civil work, everything has to be seamless. This is where a brand scores over the local installers. Look for companies that have been around for a long time and use branded products, you don't want to end up probing for the original manufacturers to avail that warranty clause. If you choose to go ahead with a brand, you won't get the surprise of hidden costs in the middle of the project as there will be complete transparency, you will get efficient rooftop panel design ensuring maximum generation and there will be no compromise when it comes to your safety.


What is operating principle of SOLAR mode in Power Conditioning unit (PCU)?

The SOLAR mode is the power generation mode. This mode is to be selected in places where grid power is stable and available. The objective is to reduce the dependence on grid power. When the day starts, the PCU first charges the battery. Once the battery has charged, it then disconnects the load from grid and connects to the UPS. Simultaneously, the Solar Panel will be charging the battery and so the load runs on Solar Power. In the evening when the sun sets, the UPS continues to supply the load from the battery. This continues till the battery reach reserve level after which the load returns back to grid supply. It continues in grid till next day morning and then the solar charging takes over. Grid charging will happen only if the battery has gone below reserve.


Is it required to take the battery for external charging frequently?

The Power Conditioning unit (PCU) has a fully automated & complex charging algorithm using Constant Current-Constant Voltage (CC-CV) method. Since in the solar mode frequent charge-discharge happens, to ensure good health of the battery automatic equalize charging is done every 30 days. Hence no external charging is required.


Can I connect entire building load to the Power Conditioning unit (PCU)?

In a PCU, the load is automatically changed to UPS and grid depending on its operation. Hence, if excess load is installed in grid mode, then when it goes to UPS, it may trip in overload. It is recommended that only the loads that normally runs in the UPS mode is connected to the system.


Will my system generate during night?

The Solar plant will generate electricity only during the Sunny hours, typically between 6 A.M. to 6 P.M and will not generate any electricity during the night. You must source electricity from Grid or the DG set during the night time.


Is Solar Power cheaper than the diesel power?

Solar power is much cheaper than power from diesel generators. Today average power from solar is Rs. 5-7 per KWh (For commercial and Industrial segments) while average power from diesel generator is Rs. 17 per kWh (a litre of diesel generates around 3-4 kWh).


What is a Grid Connected Solar Rooftop System?

In grid connected rooftop or small SPV system, the DC power generated from SPV panel is converted to AC power using power conditioning unit and is fed to the grid either of 33 kV/11 kV three phase lines or of 440/220 Volt three/single phase line depending on the capacity of the system installed at institution/commercial establishment or residential complex and as per the regulatory framework specified for respective States. These systems depend on the reference voltage provided by the grid for their operations and do not work when the grid is down. Thus, it is a combination of solar PV and the grid. These systems generate power during the day time which is utilized fully by powering captive loads and feed excess power to the grid as long as grid is available. In case, where solar power is not sufficient due to cloud cover etc., the captive loads are served by drawing power from the grid.


Which Solar PV system is suitable for my project?

There are various factors involved in choosing your PV system. You might want to research on them or get in touch with professionals in PlasmaSolar llp.

  • Energy Consumption Pattern
  • Power Cuts or outages
  • Various Govt. Policies like Net Metering, Grid Power Access or subsidies on Solar power.


What is the duration of warranty on solar panels?

Solar PV panels manufactured as per National and International standards are robust and can withstand the normal stresses subjected to nature. Hence they are not fragile. Don't worry about the solar panels warranty, as the panel's come loaded with 25 years of performance warranty.


Where can solar plants be installed?

Such rooftop systems can be installed at the roofs of residential and commercial complex, housing societies, community centers, government organizations, private institutions etc.


In case of grid failure, is there any chance for electric shock to the person who is repairing? What is “Island Protection”?

In case the grid fails, the solar power must be fully utilized or stopped immediately feeding to the grid so as to safe-guard any grid person/ technician from getting electrocuted while working on the grid for maintenance etc. This feature is called "Islanding Protection".


How much roof area is required to set up the grid connected rooftop solar system?

1 kW grid connected rooftop solar system generally requires 10 - 12 sq. metres (130 square feet) of flat, shadow-free area (preferably south-facing). Actual sizing, however, depends also on local factors of solar radiation and weather conditions and shape of the roof.


What are the advantages of Grid-Connected Rooftop Solar System?
  • Electricity generation at the consumption center and hence Savings in transmission and distribution losses
  • Low gestation time
  • No requirement of additional land
  • Improvement of tail-end grid voltages and reduction in system congestion with higher self-consumption of solar electricity
  • Local employment generation


What is “net metering”?

The grid connected rooftop system can work on net metering basis wherein the beneficiary pays to the utility on net meter reading basis only. Alternatively two meters can also be installed to major the export and import of power separately. The mechanism based on gross metering at mutually agreed tariff can also be adopted. Net Metering allows you to sell excess solar power back to the grid and thus results in maximizing the savings of the solar project. Net-meter (bi-directional meter) is having provision to record energy imported from the grid to meet the load and energy exported to the grid after self- consumption. Both energy import and export records in the net-meter. The difference between Export and Import readings is the actual energy consumed/delivered.The net meter records surplus energy exported to BESCOM grid. When your system generates less energy than your consuming load, the meter records energy imported from BESCOM grid.


Are all consumers eligible to install solar rooftop systems to avail net metering facility?

Yes. All registered metered consumers coming under the jurisdiction of ESCOM area are eligible for installation of the solar RTPV system.


How the billing and payments are made with Net-Metering?

The consumer shall receive monthly a net import/export bill indicating either net export to the grid or net import from the grid. In case of net import bill, the consumer shall settle the same as per existing norms. If it is a net export bill (after self-consumption), net credit amount payable will be deposited by the ESCOM into consumer’s bank account, provided by the consumer at the stage of submission of application.


What is “Feed-in-Tariff”?

In feed-in-tariff the Government offers a tariff for purchase of the solar power generated from such plants.


Among “net metering” and “feed-in-tariff”, what is preferred?

Net metering mechanism is more popular among States.


What is the potential of solar power available in India?

According to a study conducted by TERI, a potential of 124 GWp SPV Rooftop plants has been estimated in the country. This can be achieved through active supports from the States.


I want to install solar panels on the roof of my house. How should I go about it?

Individual household consumers can get off-grid rooftop systems installed on their roofs through MNRE channel partners like PlasmaSolar llp. to avail government subsidy.

For setting up grid-connected systems in select cities/states that are being covered under SECI Large-scale Grid-connected Rooftop PV programme (Phase IV), consumers may contact any of the developers selected by SECI. For setting up grid-connected systems in other areas, consumers may contact the respective State Nodal Agencies to find out if the same is permitted in their area. PlasmaSolar llp. provides other solar energy services as well - Solar Water Heating System, Solar pumps, Solar home lighting systems, Solar street Lighting Systems etc.


What are the requirements from the State to promote grid-connected rooftop solar systems?
  • States should have conducive solar policy to allow the grid connectivity.
  • State Regulators have issued tariff order for appropriate tariff, net-metering/feed-in tariff and the grid connectivity, and
  • The Distribution Companies agree to allow grid connectivity and purchase the electricity on feed-in-tariff or through net metering arrangement.
How many States have policies to promote grid-connected rooftop solar systems?

So far, 13 States/UTs namely Andhra Pradesh, Chhattisgarh, Delhi, Gujarat, Haryana, Karnataka, Kerala, Punjab, Rajasthan, Tamil Nadu, Uttarakhand, Uttar Pradesh and West Bengal have notified policies that include promotion of grid connected rooftop solar systems with net metering. Regulation from the State Electricity Regulatory Commission is also required to allow net metering/ feed-in-tariff.


How many States Regulators have notified orders to promote grid-connected rooftop solar systems?

20 State/UT Regulators from Andhra Pradesh, Chhattisgarh, Delhi, Gujarat, Haryana, Karnataka, Kerala, Odisha, Punjab, Rajasthan, Tamil Nadu, Uttar Pradesh, Uttarakhand and West Bengal, Andaman & Nicobar, Chandigarh, Dadra & Nagar Haveli, Daman & Diu, Lakshadweep, Pondicherry and Goa have so far issued these regulations for net-metering/gross metering.


Which organizations are setting up the projects for end users?

The programme is being implemented through multiple agencies for rapid up-scaling in an inclusive mode. These agencies are:

  1. State Nodal Agencies (SNAs)
  2. Solar Energy Corporation of India (SECI)
  3. Channel Partners like PlasmaSolar llp.:
  4. Renewable Energy Service Providing Companies (RESCOs)
  5. System Integrators (EPC)
  6. Manufactures of any component of the Solar Plants
  7. Project developers
  8. Vendors/ suppliers of solar equipment
  9. Reputed and relevant NGOs of National level
  10. Financial Institutions/Financial Integrators

The Financial Institutions like NABARD, National Housing Banks, Other Banks, IREDA, SECI etc.

  1. Other Govt. Departments/Agencies

The other Govt. Departments/Agencies i.e., Railways, Defense/Para Military Forces, Local Government Bodies including Municipal Corporations/Municipalities, PSUs, Institutions, Development Authorities, DMRC, State Departments interested in directly implementing the programme.


Are housing societies eligible for subsidy under Solar Energy Corporation of India SECI’s Large-scale Grid-connected Rooftop PV programme?

Solar Energy Corporation of India (SECI) does not provide subsidy directly to the rooftop owner, but rather to the project developer. Housing societies may approach any of the developers selected through the competitive bidding process to avail the benefits of the programme.


I have a large tract of barren land and I want to set up a solar plant. How should I proceed?

There are a number of Solar Power Developers in the market. You may engage their services. Around 5 acres of land is required for setting up a 1 MW SPV plant with crystalline Silicon technology. With Thin Film technology, land requirement is slightly higher.


What are the tax exemptions/duty exemptions for solar plants?

Several tax/duty exemptions are available for solar plants depending on the respective state solar policies where the plants are located. Various states offer a bouquet of incentives (such as exemption from Open Access charges, feed-in tariffs, tax benefits, accelerated depreciation etc.) to solar power projects that are set up under their state schemes.


What is a Solar Park?

Solar Park is a concentrated zone of development of solar power generation projects. The parks are characterized by well-developed proper infrastructure where the risk & gestation period of the projects will be minimized. Various infrastructure like transmission system, water, road connectivity and communication network etc. will be developed. There will be 25 Solar Parks in various states, each with capacity 500 MW* or above, thereby targeting a cumulative capacity of around 20k MW.

Solar Power Developers would have to arrange for their own buyer of power for Projects that are set up within the Solar Park, either by participating in some competitive bidding process, or through mutual negotiations or on nomination basis or for captive use or any other means.


Should I install rooftop solar panels?

Whether you should install rooftop solar or not depends upon a lot of factors, none more so than whether you have a free rooftop with enough space and shadow-free area. Post that it depends on what kind of electricity bills you are generating and what kind of power backup you have. Should you need more assistance ask for a call-back or request a site survey from PlasmaSolar llp.


Is it worth installing solar panels in my house in India to power all my electrical equipment and completely cutting off power coming from the grid, keeping in mind the initial investment and long-term savings?

Installing a rooftop solar PV system is any day a wise choice. It will help you to reduce your monthly electricity bill. But going completely off power from the grid might not be the best thing to do. Why? If you completely cut-off from grid, then you will be needing batteries for storing the light energy that is converted into electricity. This energy then shall be re-converted for use and it is here that efficiencies of conversion come into play.

A grid-tied solution with net- metering is perhaps a better choice. You can enjoy all electricity generated by panel during day time and during night time, you can take power from grid. In a Grid-tied or an On-grid system you have a choice of power sources your own Solar Power Generation System or the Grid. If you consume more than you generate, you pay for the excess units. On other hand, if you generate more than you "consume" then you get paid for the excess units.


What role does an inverter play in a solar PV system?

The most crucial component of a solar power plant is an inverter. It acts as an interface which converts power produced by solar panels into electricity which can be consumed to appliances. The type of inverter being used depends on the kind of solar power system you are going for. Grid tied solar power systems need high efficiency power inverters for optimising the performance. Another kind of high efficiency solar inverters are there for the off grid solar power system that can charge batteries both from solar and grid power. The inbuilt MPPT (Maximum Power Point Tracking) charge controllers in some good quality inverters extract up to 30% more power from solar panels. Majority of electrical equipment used for domestic/commercial/ Industrial purposes are of AC system. So, it is necessary to convert solar power generated at DC system to AC system. An inverter will convert DC to AC system.


How critical is the quality of the structure on which the solar panels are mounted?

It is the most critical part as it acts as the skeleton for the entire system, a sturdy structure will result in years of power generation as it need to withstand strong winds and other natural forces. The type and orientation of the structure varies to a great degree depending on multiple factors associated with the location where the solar power system needs to be deployed. The structure for rooftop solar installation on a flat roof is completely different than that for a slanted roof. The height of your roof is another major factor which determines the composition and alignment of the structure. The quality of the material used has to be as per the MNRE (ministry of new and renewable energy) specified norms. The structure needs is mostly made of galvanised iron, which is not only stronger than normal iron but rust proof as well making the solar power system last long.


Can I use normal cables in a rooftop solar system?

You can't use any regular cable for your solar power system. Specialised cables custom made for solar power plants are used to ensure minimal loss of electricity being generated. They are UV protected and strong and long lasting enough to withstand the rigours of nature - be it peek of summers, incessant rains or thunder storms. Use of any ordinary cable is a big health hazard as well with high chances of electrocution for the people in vicinity of the system. Bad quality wire will not only make you solar power system in effective but will result being more expensive as you will end up changing the wires of the entire system in the exposed parts get deteriorated resulting in the risk of electrocution.


Apart from panels, inverter, batteries and structure, what else is crucial for setting up a solar power plant?

These are the elements which are essential for proper functioning and safety of the system. No compromise must be made on their quality or it will jeopardise the entire solar power system. In terms of their functioning, while Junction Boxes are used to conceal the wiring connections all across the system, Conduits on the other hand are used to protect the wiring of the solar power plants, they can be rigid or flexible or a mix of both based on the requirement. Lightning Arrestors are deployed to save the entire set up in case of a lightning strike, especially during monsoon while Earthing, which is a grounding system connecting the residential solar power plant to earth, is done in order to give passage to excess electricity during the lightning strike and safeguarding the entire system in the process.


What all do one need to take into account while installing a rooftop solar power plant?

The installation of the solar power system needs to be done with precision in order to generate maximum electricity through the solar power plant. No two roof-tops are the same therefore the process requires system design and careful supervision to ensure proper installation of the solar rooftop power plant. Solar panels used in any solar power system should be installed facing South direction. Tilt angle of solar panel should be around 30% in India, but it varies as per the height of the installation. Solar panels must be grouted using anchor bolts or concrete foundation to ensure durability in rough conditions. UPS and batteries must be installed as close to the panels as possible to minimize DC transmission losses. One needs to ensure that the maximum permissible voltage is not exceeded when connecting the panels in series. There should be a minimum gap of 5 mm between two solar panels to allow for any expansion in materials. The solar panels being interconnected must be of the same type (mono or poly) and same power class. There should be no shade or shadow on the solar panels as this may lead to losses, formation of hotspots etc.


What effect does shading have on the performance of the solar panels?

The performance of solar (PV) panels is affected by the shading effect of surrounding trees and buildings, basically anything that casts a shadow on to the panels. The sun light converted into energy by the PV panels shall depend on the amount and duration of the shadow falling on it. Lesser the shadow, more the energy! No shadow - maximum energy!


Which direction should the solar panels face and why?

Solar panels need to face true south direction for maximum power generation. The reason behind it is that when sun moves from east and goes to west, it leans towards south direction. Irrespective of which part of year it is, inclination will always be towards south. Hence for the optimum harnessing of sunlight, the solar PV panels should ideally face south.


At what angle do one needs to place the solar panels for maximum output?

The angle at which the solar panels are fixed according to your location's latitude. In general, the angle of tilt will lie between 9 to 12 degrees in southern part of India and 25 to 30 in north India. The angle decreases as the altitude of installation increases to nullify the impact of high speed winds on the installation.


How important is regular cleaning of solar panels?

Solar Panels have to be cleaned at least once every week. It would be great if you can manage to do it as often, to make the most of the sun rays falling on it. It is recommended to do it using a wipe after a strong water spray.


How should I go about the maintenance of my rooftop solar power system? What is the typical maintenance required for a solar power system?

A solar rooftop power system will deliver the full return on investment when it runs as smoothly as possible. This means periodic inspections of the individual components of the system. A timely intervention can prevent the threat of diminished output or downtime or a safety hazard. That is why it's important to get in touch with a reputed brand like PlasmaSolar llp. to install your solar system so that all this can be taken care off.

The most crucial part of maintaining a solar power system and making sure of the optimum power generation is to keep the solar panels clean. Apart from this, all the main components come with performance warranties, so you don't have to worry about the other stuff too much. Solar panels come with 25 years of performance warranty while that of inverters and batteries keeps on varying.


Does solar power system work only on sunny days?

No, it even works when it's cloudy! Obviously the power generation will not be optimal but it does not stop working. Also, with 300 sunny days, India is blessed to be the best destination for solar power generation.


What types of buildings is this suitable for?

It's suitable for all type of buildings. The only prerogative is that there should be a roof on top of it, strong enough to support the structure. Installation also varies depending on whether the roof is slanted or flat. In India, we mostly have flat roofs and the structures are created accordingly. The position of the surrounding elements, such as buildings or trees, which can cause shade on the panels play a crucial role in determining the area on the roof suitable for optimum solar power generation. At times there are obstacles on the roof, such as water tanks, which affects how the structure to support the solar panels will be erected as well.


Can solar panel be used for running water pump, refrigerator and air-conditioning?

Absolutely. One just needs to make the calculations correctly in terms of what all appliances are being run on solar. Power requirement of a water pump generally lies between 250 to 1100 watts. Just make sure that the total accumulated load does not exceed what is being generated by the solar panels. It also depends on what type of system do you have. If you have an on-grid system, you can use the solar power during the day part by directly connecting the water pump load to the solar set up. In case of an off-grid system, you can use the energy stored in the batteries to run your water pump any time during the day. The duration of usage will depend on the capacity of the batteries and the level of their charging.


What are the business models that can facilitate the promotion of grid connected rooftop solar systems?

There can be many possible business models, some of which can be considered are as follows:

(a) Solar installations owned by consumer

  1. Solar Rooftop facility owned, operated and maintained by the consumer(s).
  2. Solar Rooftop facility owned by consumer but operated and maintained by the 3rd party.


(b) Solar installations owned, operated and maintained by 3rd Party

If the 3rd party implements the solar facility and provides services to the consumers, combinations could be:


  1. Arrangement as a captive generating plant for the roof owners

The 3rd party implements the facility at the roof or within the premise of the consumers; the consumer may or may not invest as equity in the facility as mutually agreed between them. The power is then sold to the roof owner.


  1. Solar Lease Model, Sale to Grid

The 3rd party implementing the solar facility shall enter into a lease agreement with the consumer for medium to long term basis on rent. The facility is entirely owned by the 3rd party and consumer is not required to make any investment in facility. The power generated is fed into the grid and the roof top owner gets a rent.


(c) Solar Installations Owned by the Utility

  1. Solar installations owned operated and maintained by the DISCOM

The DISCOM may own, operate and maintain the solar facility and also may opt to sub contract the operation and maintenance activity. The DISCOM may recover the cost in the form of suitable tariff. The electricity generation may also be utilized by DISCOM for fulfilling the solar renewable purchase obligation.


  1. Distribution licensee provides appropriate viability gap funds

The DISCOM may appoint a 3rd party to implement the solar facilities on its behalf and provide appropriate funds or viability gap funds for implementing such facility.


What are the models for implementation of Rooftop PV systems by SECI?  What is the difference between CAPEX and RESCO / OPEX model?

Currently, SECI implements the rooftop scheme under two models:

  • CAPEX Model: Here, the entire system is owned by the rooftop owners. Responsibility of O&M for the system lifetime (25 years) is also with the rooftop owner. Developer is responsible for installing the system and initial 2 years O&M. In this case, the developers are selected through a system cost-based reverse bidding. Selected bidders are offered 30% subsidy on the system cost (exclusive of taxes). In this, end consumer owns the asset (Plant) and can claim accelerated depreciation.
  • RESCO Model: Here, the entire system is owned by the developer. Responsibility of O&M for the system lifetime (25 years) is also with the developer. Rooftop owners may consume the electricity generated, for which they have to pay a pre-decided tariff on a monthly basis. Excess generation may be exported to the grid, subject to availability of requisite state regulations. In this case, the developers are selected through a tariff-based reverse bidding (in phase IV). In this, the investor owns the asset (Plant). The consumer and the producer enters a PPA (power purchase agreement) for a decided duration of time which is typically 15-25 years. During the tenure of PPA, the consumer pays the producer for the power generated at a decided tariff. After the PPA terminates, the asset is transferred to the consumer.


Which model is best for me?

For consumers that have adequate manpower/expertise for O&M, rooftop access concerns, availability of funds upfront, CAPEX model is better. Consumers in states that have net-metering regulations can take benefit of the same in case they have substantial excess generation.

On the other hand, consumers who prefer not to take responsibility for the system O&M, do not have rooftop security concerns and prefer to pay on a monthly basis rather than bulk upfront payment may choose to go for RESCO model.


What is the normal payback period?

The Return on Investment (RoI) takes place in around 4.5 years. Then you earn for a minimum of 20 years. Not only you generate your own electricity, you also help reduce the carbon footprint contributing to a healthier environment and making money in terms of savings either due to reduced electricity bill (if you are using an on-grid solar system) or reduction in diesel cost (if you are using an off-grid solar system).


What is the Financial Assistance provided by the Government Ministry of MNRE?

There is a provision of Central Financial Assistance of 15% of the total cost or Rs. 12 per watt or Rs. 1.20 crore per MWp under the Grid Connected Rooftop and Small Solar Plants Programme of the Ministry. This CFA has been reduced from 30% to 15%.

Subsidies are available from multiple channels for setting up Rooftop PV projects:


  1. Subsidy/Support from Central Government through MNRE: For systems upto 100 kWp in size, upto 15% subsidy can be availed with the help of MNRE-empanelled channel partners. For systems of sizes 100 kWp-500 kWp, subsidy can be availed through Solar Energy Corporation of India.
  2. Subsidy/Support from State Government through State Nodal Agencies (SNAs): Subsidy support is also available in various states. The percentage of subsidy varies according to the state policies. Interested consumers may contact their respective SNAs for more details.


Do individuals get any subsidy/tax benefits for adopting solar systems?

Absolutely, In case of rooftop Grid-Tie solar power system, the owner must complete all the necessary requirements for getting net-meter installed. This may require additional time and fees depending on the local electricity utility. However, in case there are subsidy schemes offered by local government, additional documentation may be required for subsidy. MNRE announces subsidy and its disbursement procedure on its website regularly, you may pay them a visit as well to know more.


What are the other fiscal incentives available for Solar Rooftop Systems?

There are provisions of concessional import duty/excise duty exemption, accelerated depreciation and tax holiday for setting up of grid connected rooftop power plants.


What efforts Government is making to providing loans for solar rooftop systems?

Department of Financial services has instructed to all Public Sector Banks to encourage home loan/ home improvement loan seekers to install rooftop solar PV plants and include cost of system in their home loan proposals. So far, nine PSBs namely Bank of India, Syndicate Bank, State Bank of India, Dena Bank , Central Bank of India, Punjab National Bank, Allahabad Bank, Indian Bank and Indian Overseas Bank have given instructions to extend loan for Grid Interactive Rooftop Solar PV Plants as home loan/ home improvement loan.


How to go about govt. approvals & subsidies for roof-top solar plants?

In case of rooftop Grid-Tie solar power system, one must ensure that all the necessary govt. requirements for getting net-meter installed are being taken care of. This may require additional time and fees depending on the local electricity utility. However, in case there are subsidy schemes offered by local government, additional documentation may be required for subsidy. Ministry of New and Renewable Energy (MNRE) regularly announces subsidy and its disbursement procedure on its website, it's recommended to visit the same.