In simple terms, Rooftop Solar Photo Voltaic System (RTSPV or RTS in short) consists of silicon based solar panels that absorb sunlight and convert them into electric energy (DC current) and make it available for use after converting them into AC using solar Inverters. RTS installations consist of Solar Panels, Solar Inverters, AC/DC safety components etc.

It is the cleanest and cheapest energy source compared to all other energy source (like thermal, nuclear, hydro etc.) as of today. With diminishing cost of solar power system components it will continue to be the most economical power source in future. All other source of energy produces harmful carbon emission into atmosphere when power is generated except solar power systems. You go Solar, you decide to go Green to save environment. It is that noble a gesture from those who embrace solar energy initiatives.

Any individual with a KEB electricity connection with a sanctioned load and has open rooftop space to install PV panels can go for RTS installations. The capacity of installation (in KW) will be decided/limited to the maximum KEB sanctioned load for a household/industrial connection. However a higher than sanctioned load capacity can be installed by applying for load increase with KEB while going for RTS installation.

Typically 3 types.

1.) On-Grid OR Grid-tie installations.

2.) Off-Grid/Hybrid Systems also called as Solar UPS and

3.) Ground mounted Utility Scale Solar Installation.

1.) On-Grid OR Grid-tie installations – They are connected to KEB power grid. The power generated by RTS system gets exported to grid during the day. Consumption of power happens like before from the grid. At month end, the units generated/exported by RTS and units consumed from Grid is reconciled and difference units are either charged or rewarded as per buy-in tariff agreed in PPA. In On-Grid option, the key objective is to save money by captive consumption of power at near-zero cost and sustained cost reduction for 25 years. This is also inexpensive solution compared to off-Grid because of no investment on batteries. Key point to be noted is that on-Grid systems DO NOT generate electricity when grid is down. This is a safety measure to avoid accidents if solar generated power gets exported to grid when maintenance personnel are at work doing grid maintenance.

2.) Off-grid Systems are not connected to grid. Key objective here is to have uninterrupted 24×7 power backup and enjoy low cost power. This is marginally expensive because of the cost of batteries involved . Off-Grid systems generate power irrespective of grid is up OR down.

Same above 2 options (off-Grid & Grid-tie) are available for commercial. However as commercial enterprises power requirements are generally large, battery based UPS solution may not be cost effective. Hence, one large right capacity on-Grid system supplemented by a small solar UPS system with optimal # of batteries of adequate AH capacity for backup would be an ideal option.

Normal UPS has batteries that use grid power for charging the batteries while Solar UPS batteries get charged thru solar panels. Advantage of solar UPS is that they generate power during day time, that gets consumed as well, and charges the batteries. When power shutdown happens during the day, power generated by panels gets consumed instead of drawing power stored in the batteries which can be reserved for night time usage. Solar UPS is comparatively expensive (because of advanced deep cycle C10 battery costs used which has 3-4 longer years life compared to normal UPS batteries). Cost of grid electricity needed for charging the batteries is nil as it uses free solar generated power.

In Grid-tie systems, Hybrid system is a compelling option to address the “No Power” issue during Grid power outage. Hybrid systems are tied to a grid but also has special hybrid inverter and battery combination that allow the system to provide power in case the grid is down. Inverters are specialized, expensive and hence cost of the RTS would be significantly higher than other 2 options. Also the maintenance support.


Polycrystalline solar panel is made of solar cells from many crystals in each cell. These panels are made of silicon. To make the cells of polycrystalline panel, fragments of silicon are melted together to form the wafers that harness the light energy into electricity. The productivity level of polycrystalline solar panels is typically low compared to Mono.
Monocrystalline solar panels are made of silicon wafers from single piece of silicon crystal. The silicon used to make these solar panels are high in purity. Monocrystalline panels are marginally expensive due to the higher cost of production, but they generate more power units per square unit area.
You can expect both poly and monocrystalline panels to have an average lifespan of between 25 to 30 years. However, these panels will not stop producing electricity altogether at the end of this period, it will only generate power at lesser efficiency due to some degradation.

If you have open rooftop space constraint, then it is advisable to go for Monocrystalline panels as they produce more power in lesser area compared to Poly. Otherwise polycrystalline is economical option.

As per study results, a 1KW RTS installation should be able to generate an average of 4 Units/Day. On average, regions in Karnataka with good solar irradiance would get anywhere between 5+ units in summer and 3.5+ units in rainy/winter days. Hence 4 units /day/KW installed capacity is a good assumption for productivity of RTS. However this number is dependant on the design of system, shadow-less south facing roof top with right gradient and weather conditions during the year.

Half-cut cell modules have solar cells that are cut in half, which improves the module’s performance and durability. Traditional 60- and 72-cell panels will have 120 and 144 half-cut cells, respectively. When solar cells are halved, their current is also halved, so resistive losses are lowered and the cells can produce a little more power. Smaller cells experience reduced mechanical stresses, so there is a decreased opportunity for cracking. If the bottom half of a module is shaded, the top half will still perform.

No. There will be numerous brands, some imported some India made. Not all can be considered as top rated. Hence you may find only few are empanelled brands with MNRE and KEB. Some tier-1 brands have extensive R&D setup along side manufacturing setup that one should consider while deciding. Some are certified by leading international certifying agency like PVEL for solar industry and gets rated in PV Module rating score card every year. So naturally companies that have long industry presence and focus on R&D and Quality are to be considered as against lesser known brands that get imported and get installed in your RTS. This would have a significant impact on your warranty support in future if brands used don’t have India presence after few years.

As the lifetime for any RTS is 25+ years it is imperative that top quality products to be considered as part of solution. Not only for PV Panels, Inverters and Batteries but also all other sophisticated electronic components and connectors, cabling that go into the system need to of tier-1 industry standard. KEB insists that only MNRE empanelled components are to approved. Unknown brands will pose issues when warranty claims in future. Strong India presence would be a prerequisite for Panels and Inverters to consider. Local presence for post implementation support is key. Any delay due to turn around time to attend to issues will result in days of power generation downtime. Look for extras if additionally being charged as actuals. They may impact your budget. There are few mandatory requirements that need to met by installers as per KEB norms like safety railings, pathways, non-standard products etc. Good to have them noticed in proposals before going ahead with the project.

As a thumb rule, it is approx. 50-60 SqFt per KW based on Mono or Polycrystalline panels used. It may vary if shadow prone rooftops to avoid such areas. Shadow may considerably impact the power generation if solution design is not done properly by deciding the panel string size, full/halfcut panel, #of charge controllers in Inverters, gradient of panel array etc.The area required may differ if single/multi axis rotator solutions are used for increased power production to follow the sun, especially on ground mounted solar power plants.

If your power requirements are in MWs ground mounted solar park OR Utility-scale solar power plants could be an option. The solar energy generated here is exported to KEB grid and then sold to other large power consumers via power purchase agreements OR used for captive consumption in same locale or in another geo location.

At SmartEco, we undertake each RTS installation project as EPC contract where we take up end-to-end tasks that starts from liaison/ coordinating paperwork at CESCOM for obtaining the Power Purchase Agreement (PPA) between you and KEB till the RTS is commissioned and approved by KEB. You only provide required documents and signatures on Forms. We will take care of all other aspects of installation till you get your first net metering bills from CESCOM. Needless to say, our proposal quote includes all costs related to this, so that you don’t lose sleep on this when project is executed.

Typically it is between 4-6 weeks from the day required document is submitted to obtain PPA along with advance. Unforeseen delays very rarely possible when shortages of semiconductor based components in market as seen during Covid lockdown OR due to minor delays in approvals from CESCOM as per their priority workload.


Typically smaller installations are marginally expensive KW-wise as higher the capacity lower the KW-wise price because of scale and discounts offered by OEMs. Residential 3KW-5KW RTS may come at approx. Rs.60-70K per KW. These are ballpark figures excluding GST and other costs. SmartEco provides free cost estimates after site visit and free energy audit.

Ballpark cost estimates for large 100-200KW commercial RTS will be at approx. Rs.35-40K per KW excluding GST and other costs. These are ballpark figures excluding GST and other costs. SmartEco provides free cost estimates after site visit and free energy audit. We will also provide a detailed work out of ROI for the investment you make on RTS to compare how your returns are justified.

Currently the prevailing buy-back tariff is fixed at Rs.4.02 per unit for residential RTS installation and Rs.3.19 per unit for commercial. This is subject to change in future as per KEB discretion.

Currently subsidy is limited to residential RTS installations only. There is a policy that is detailed in the central government portal https://solarrooftop.gov.in/
If you enrol for the subsidy scheme the KEB buy-back tariff will be Rs.1.50 less for you for 25 years. That means if you have surplus power export every month to grid, you will be paid by that much amount less for every unit instead of Rs.4.03 per month without subsidy.

Yes. Available for residential projects only. There are some designated banks that SmartEco has associated with that allow loans upto max of Rs.50L. Loans upto Rs.10L without any collateral. Details may be obtained on request. It is noteworthy to mention that the ROI figures that RTS projects of diff KW capacity offer are in the range 17% – 25% for residential projects and 35% – 48% for large commercial projects of 30KW – 200KW are after taking into consideration of this cost of financing at 10.5% interest rate.

Very few investment opportunities would guarantee the ROI that RTS projects would return. The returns are sure shot because CESCOM tariff would increase at regular intervals during next 25 years. It is estimated that the grid tariff will be 2.5 times the current tariff on 25th year if nominal increase of 3% over the years is assumed. This would mean that the captive consumption savings itself will be significant over the years. Added to it, the interest earned on this savings after initial payback years of 3-5 years, it will be substantial earning every year over 25 years lifetime of RTS.

For commercial RTS projects, there are 2 important benefits. You can avail accelerated depreciation that allows you to claim entire 100% of investment as expenses within 3 years and GST claim benefits as well. Hence the ROI is better for commercial projects as net investment cost comes down after availing these benefits.

The key components of rooftop solar photo voltaic (RTSPV) power systems are Solar Modules (PV Panels) and Solar Inverters. Along with this, there are other components that are integral to the installation like Panel mounting structures, DCDB with SPDs, DC Disconnect, DC Fuses, AJB with Fuses, Busbar, Terminals, ACDB with MCB, SPD and Contactors, Bidirectional Meters, MC4 Connectors, AC,DC Cable & Wiring, AC Earthing, DC Earthing, Remote Monitoring system etc. Every component is crucial for smooth functioning of RTS system for 25 long years and hence needless to say you look for proven good quality brands.

As there are numerous brands for each components of RTSPV system it would be tricky to decide what is the best value-for-money proposal. It would be wise NOT to go by most economical quote presented. Quality components always come with a price that are justifiable with the quality and durability credentials of the product. So tier-1 product brands that are empanelled with MNRE/KEB may be marginally expensive compared to lesser known imported brands. Look for what you are missing w.r.t quality, warranty support, India market presence of products when you decide on a non-standard brands. Another factor that is not to be missed is what are shown out-of-scope in the proposal, in other words what are shown as extra. These line items may cost substantial like cost of arranging for PPA with CESCOM, panel/battery mounting structures, earthing/lighting arrestors, transportation if shown separately etc. SmartEco’s commercial quote will generally be all inclusive so that you need not worry about the additional cost burden at later stage.

SmartEco projects come with 1 year of free post implementation support that include all technical support, periodic inspection and replacement of parts if goes bad during the period. We also remotely monitor power generation using remote monitoring App provided as part of solution. Other support during post installation is help for coordinating with CESCOM for streamlining the net metering process ensuring 1st net metering billing is done accurately and credits to your bank happen as per agreement.

When you opt for net-metering with CESCOM, the solar power units generated by RTS get exported to grid during the day and your consumption during night happens by drawing power from grid. Excess units if you consume only gets charged to you. If surplus units are generated and exported, you gets a credit by CESCOM at agreed buy-back tariff (@4.09/unit for residential customers and @3.19/unit as on Jan-2023 for commercial customers). This credit happens automatically to you bank account registered with CESCOM after few initial billing/accounting cycles at CESCOM. SmartEco will provide liaison support to streamline this activity till 1st billing cycle credit happens successfully, and then on it will be an automated process that ensures that your bank account gets credit every month.

Though at nascent stages of power generation efficiency and adoption, these are future avenues of harnessing solar power going forward. Building-integrated photovoltaics (BIPV) are solar power generating products or systems that are seamlessly integrated into part of building components such as façades, roof tiles, walls and windows. Yet to become commercially available as mainstream renewable energy option.

YES. In farmhouses around Mysore where continuous power availability is a challenge, SmartEco helped installing Integrated solar power systems for irrigation pumps PLUS home appliances needs. During the day the RTS power can be channelled to irrigation as many hours as needed and can then switch over to house hold needs at night. Sufficient backup capacity is to be arrived based on needs and battery bank capacity to be installed.

The AC power supply can be classified into single-phase (1-phase) and three-phase (3-phase). In general, a single-phase power is used where electricity requirement is low. for running small residential appliances. The three-phase power carries a heavy load and can run large machinery in commercial setup. Typically smaller capacity residential power load sanctions may be given as 1 phase by KEB. If so, RTS inverters can be of 1 phase support which are marginally cheaper. But residences that has three-phase power connection that runs water pumps etc. need to go for three-phase inverters. If your residence already has single-phase power, you should make sure that you have a single-phase inverter installed and same goes with three-phase.

The integrated All-In-One solar lights come with all components like PV panel, battery, charge controller, sensors etc. all built into one unit sold by vendors online OR imported. The warranty is also limited to short period of replacement because repairs may be difficult of individual parts. Whereas the custom designed are assembled by using quality branded components of required specifications so that you get what you need w.r.t PV panel wattage capacity, Battery technology like Li-Ion/LiFePO and option of pole height, gauge of metal, GI/SS/MS etc. In case of technical issues, the problem can be zeroed down into each component and can be rectified/replaced as per warranty of each.
Custom designed street lights can host surveillance cameras drawing power from the same solar battery bank thus eliminating need of another electrical wiring and cameras can be housed on the same locations where areas are well lit. Optional automaton can also be designed based on sensor based technology available.
Refer to www.smarteco.in/projects for custom designed street lights by SmartEco.


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