Why I Invested in Rooftop Solar PV and What Have I Learnt: PART 1

Ever since I was interested in EVs and I got my Kona, I wanted to study rooftop solar for completing the clean energy generation to clean transportation loop. I got in touch with many solar rooftop system integrators and installers. Finally found Ecosoch and liked the team and their approach.

WHY I CHOSE MY OFFICE RATHER THAN HOME

I initially wanted to go for this at my home with the best available inverters and PV panels, but then realized that since I shall be at my office during the day I will effectively not be able to use the solar generation at home. A few more reasons enumerated below made me change my mind to install it at my office:-

• Higher industrial rate of Rs.7.8/- per kWh at my office compared to lower residential rates.

• Accelerated depreciation (as I know it is 40%+20%/year) that I can claim in my companies, more on this later.

• Panels need to be cleaned regularly to maintain highest possible efficiency. Office has an easy access to RCC terrace v/s a slant roof at home.

• Always better to plan system to a max of 80% of the demand units to maximize net metering benefits, more on this later.

• GST input credit can be availed in my companies.

This small-ish 13.32 kWp (Kilo Watt Peak) system was a test case that would allow me to analyze both the system economics, the workmanship and component quality used by Ecosoch. I finalized SolarEdge inverters with 12 year std warranty, monocrystalline solar panels from Waree. This system cost was hence on the higher side due to the small size of installation. I did not study or look for any subsidies, as there is always some catch if one opts for it. Since businesses anyway don’t get subsidies for solar it did not make sense to look at it. This system cost me around 60,000 ex GST per Kwp as some extra control panels were involved on the metering side. System went online on 5/6th November 2019.

The consumption at my office is around 1800-2200 kWh per month. As of May 1st 2020, the PV system had generated 9.77 MWh of electricity. I received my first BESCOM invoice on May 1st 2020 for 59 kWh. Grid export was 8.43 MWh and import to grid was 8.49 MWh. This gap is closer than it should have been due to the couple of months of lockdown due to COVID 19, when this system was the only revenue generating part of my business. Normal course of action monthly consumption should around 2100kWh and generation 1800 kWh. Power consumption happens on 6 days a week and very minimal on Sundays, whereas generation happens on Sundays/ other holidays.

Small things matter!

In this 13.32 kWp system, I got a lot of opportunity to learn what are the things needed to be focused on to get optimum generation:

1. 2 panels are connected to one power optimizer and then taken in parallel such that if any one panel is under shade, generation of only the two panels with same optimizer is affected.

A panel towards the one end of the installation with power optimizer 1.0.17, was generating 10-15% less during the first half and second half generation was good. What I found as shown in Pic 1 was the parapet wall was casting a small shadow on the corner of a panel; hence generation was 10-15% below par compared to panels beside them.Solution was simple, we got the panels moved a feet as shown in Pic 3 and generation was up 0.3-0.5 kWh/day.

2. Another major issue we always had in mind was we have some trees on the south side which come into picture during the afternoon/evening. We got the shadow causing branches trimmed (mobile tower in the neighboring building still causing shadow, but out of our control).

Solar generation from Nov 1st week 2019 to Jan 2020 middle, post 12 pm the generation used to take a deep dive. Hence generation in Nov, Dec and some days of Jan was suboptimal and a considerable increase (maybe a little to do with summer setting in) is noticeable in the monthly generation chart as shown in Pic below.

This system was perfect in terms of being a learning curve for me. But yet it did cost more due to monocrystalline Panels, and some extra electrical panels. We as a company have not gone in for financing the same. But for academic purpose, I have considered a 100% financed installation at 10% PA interest.

I have modeled the calculation such that if I were not to go solar I would have continued paying for the electricity, instead I pay off the loan for 72 months (1.95 lakh additional saving due to depreciation for the 1st 4 years). The tables above are self explanatory. After that the system provides free power till it lasts (panels have 25 year warranty and inverters 12 years with an option to extend to 25 years). If all goes as per plan and Bangalore continues to be bright and sunny most of the year by year 25, power savings would be a cool 39.65 Lakh.

I always talk about the economic reasons to go green with Electric transport or renewable energy. Any decision when taken has to make economic sense first for an entrepreneur. If going green has a very small financial burden then people will do it. But sure does feel good to be using solar power. Since system went online, total net consumption from grid for Nov 2019 to May 1st 2020 for me has been only 59 kWh, i.e. I have net used only around 0.5% (59/10900).The below data in Pic below is the icing on the cake.

DECISION TO GO FOR LARGER SYSTEM

Having observed this system for three months, I decided to go for a larger solar PV system in my Tumkur plant as that was the only plant with metal sheet roofing. More on that in blog part 2 .

Arun Bhat S

Director Krishi Group

CoFounder TCIN

Building a Community for Future