Considerations for Solar Roof-Top Set-up

Solar Roof-top is a proven technology and has been adopted world-wide in a big way. There is big push to solar roof-top in India as well. There are now reliable suppliers in the market. It is now easy to install a solar roof-top.  There are a few important considerations/ decision factors while installing a solar roof-top. These considerations are applicable whether you are an individual house owner, an apartment society or commercial/industrial entity. Please note that these considerations are applicable for the entities which have an existing source of power – state electricity grid or Diesel Generator. Let us look t them:


![if !supportLists]>(A)   <![endif]>Know Your Energy Profile – It is important for you to know your energy profile (even if you are not planning to set-up solar roof-top!). One should know the maximum and minimum power demand in kW during the month and year as well as the typical day/time when the maximum /minimum demand occurs. Please also get average demand in kW during the day and average demand during the night as well. One may require more information about the energy profile which we discuss during other points. This would be useful for the capacity determination.

<![if !supportLists]>(B)   <![endif]>Know Solar Generation Potential – Please get to know your solar roof-top generation capacity. A simple rule of thumb is 10 sq meter space is needed for 1 kW. A more detailed analysis of the location, angle, solar position, shade area can be done in a survey by a vendor. Please get more than one surveys done. Please ensure that you get survey done in the property and places where you have control. A condominium RWA may have control on the common areas while a sector RWA may not have control in sector common areas.

<![if !supportLists]>(C)   <![endif]>Off Grid vs On Grid – Let us first de-mystify these terms. Off-grid means the solar power generated can be exported back to the distribution grid while the on-grid means that the solar power can be exported to the grid.

There is a net metering policy announced by the HERC (Haryana Electricity Regulatory Commission) while make on-grid solar roof-top possible in India. An important element of this policy is that an on-grid system can export the surplus power during the day and import the power back during the night. Net metering works on the settlement basis and not on the sale of power basis (you can settle export with import and would not get paid for net export in Haryana).

To take this decision, please compare the energy profile with generation potential. If generation potential is more or less equal  or less than minimum demand in a year,  please go for off-grid.

If generation potential is more than the maximum demand or significantly higher than average daily demand, hen on-grid installation can be considered (the decision than shifts on the capital /investment considerations).

If you have very low average demand during the nights (say an office closing at 5-6 pm), do not considered On-Grid.

For other scenarios, more technical and commercial deliberations are needed to decide on-grid vs off-grid


<![if !supportLists]>(D)   <![endif]>Battery Back-up – We recommend that do not consider battery back-up for the solar power. It is very inefficient, expensive, takes significant space and requires more maintenance. If you have significant generation potential than your demand in the day, go for net metering. (Consider net metering as your battery back-up)

<![if !supportLists]>(E)    <![endif]>Cost of Solar Power - The next thing is to understand the cost of solar power. The capital cost of solar power could be about Rs 1.4 lac per kW for kW range capacity and could be Rs 1 per kW for 100 kW range. Please do get exact quote from your vendors. To determine levelized or annualized cost of power, please consider the life of system as 25 years, efficiency reduction of 10 % in 25 years and  plant load factor of 20 % (consider that on an average the solar power is available for 5 hours during the day).

<![if !supportLists]>(F)    <![endif]>Compare cost of Solar Power with Grid Power – Unless, you are surviving only on DG back-up or DG back-up is more than 15 % of your power intake, do not compare the cost of solar power with the cost of DG power . In a normal scenario, Solar Power does not replace an emergency power source such as DG rather it replaces the regular power source.  Please calculate the saving potential and work out return on investment.  Please budget an average 8% increase in the cost of grid power

If you are commercial/industrial entity, you rest assured that you would get 3-5 years as ROI. If you are a domestic consumer or condominium, you would get poorer ROI say 8-10 years.

One should do a different financial analysis. One should calculate the net present value of the solar investments and let us tell you that you would be pleased with the net present value numbers of solar investment.

Please do not keep subsidy as well as mandatory provisioning of solar power in your calculations at this stage. Only if you decide that you do not want to set-up solar power based on the considerations above, please look at the mandatory requirements and fulfill those requirements.

We believe that the following are the main impediments in the adoption of solar roof-top

<![if !supportLists]>(a)    <![endif]>Lack of Awareness – We hope that the articles like this would help to improve the awareness.

<![if !supportLists]>(b)   <![endif]>Issue of Capital – It is not very to get funding for the solar roof-up in spite of all the push by the government.

<![if !supportLists]>(c)    <![endif]>Selection of vendors – There is a problem of plenty and there is an issue of many fly-by-night operators.  Every vendor does not focus on every size segment. Please check out the vendors who are in your segment and do visit the existing installations.


We do see a day when solar roof-top would become an integral structure of urban landscape. The sooner we get there, the better it is going to be for the environment and economy. Please do share your experiences and thoughts.  You may also reach out to us via This email address is being protected from spambots. You need JavaScript enabled to view it.




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