The coming of age of storage technology in the Off Grid Solar Power System

In the late 90s, Off-Grid Solar (OGS) power system in India primarily stood for home lighting for those households who did not have access to electricity. For others, it meant a back-up lighting system to avoid periodic black-outs and brown-outs. Back then, multi-crystalline and Amorphous Silicon were the primary solar cell technologies.

Both, from a technical and commercial standpoint, OGS power system have come a long way. The efficiency of the module has increased from ~12% to ~17% (for multi-crystalline silicon module). During the same time, the total system cost for 4-5 hour back up has come down from $10/Wp to around $1.33/Wp today – 19% CAGR reduction.

In the 2000s, the solar module’s contribution in the overall cost of the system stood at ~60%. Today, this has dropped drastically and is ~20 to 25%. Whereas, during the same time, storage technology chiefly Flooded Lead Acid type battery, is responsible for ~40% of the total system cost and its share has almost doubled.

The advent of Lithium technology especially Lithium Ferrous Phosphate (LFP) battery has bought with it both advantages and new set of challenges. The dealer price of LFP works out to be $225/kWh (Depth of discharge equals 80%). The other advantages of LFP are: five-year replaceable warranty (~3,000 to 5,000 cycles) and it is maintenance free.

The challenges are primarily associated with the Battery Management System (BMS) which is in-built and hence factory designed/assembled. Sometimes these do not adhere to the technical specification as provided by the manufacturer. Secondly, many a times, the charge controller engaged to regulate the flow of current to/from the battery also behaves erratically. The problems are nascent and should be viewed as nothing more than teething trouble as the technology itself is evolving.

Despite exhibiting a price drop of 25-40% CAGR over the past two years, price of LFP continues to be a major deterrent in it’s dissemination. We believe that both push (on the supply side) and pull (on the demand side) are needed to increase the demand and reduce the price of the technology.

To this end, the engagement of National Mission on Transformative Mobility and Battery Storage (NMTMBS) approved by the union cabinet on March 2019 and chaired by the CEO, NITI Aayog, would be very helpful.

One of the objectives of the program is to “formulate and launch a Phased Manufacturing Program focusing on batteries including raw material”. Under NMTMBS, by 2022, 50 GW Lithium ion based battery production capacity is expected to be set-up in India. Several incentives too are in the offering, which includes: Reduced Minimum Alternate Tax, Land made available (at expedite clearances), Lower rate power, Waiver in customs duty, etc.

India Energy Storage Alliance (IESA) is another organization, which is engaged in the advancement of energy storage and e-mobility technologies in India. It recently recommended Ministry of Power on the proposed draft for Electricity (Amendment) Bill, 2020 to include several important issues such as National renewable energy policy, Storage purchase obligation, Define ‘energy storage’ in the Act, etc.

To conclude, the road treaded by OGS power system has had its share of pitfalls and successes. And, the benefit attained by the industry isn’t completely due to its own making. The large decrease in the price of solar modules was led by rapid dissemination of utility scale solar power. On a similar note, the large scale adoption of electric vehicles too could lead to reduced prices of electro-chemical storage technology whose benefit can be accrued by OGS and other decentralized power systems.

Sharath Rao, PhD is Managing Director, Bruhat Energy Solutions & Technologies Pvt. Ltd. He can be reached at sharath.rao@bruhatenergy.com

Bruhat Energy is engaged in the manufacture of electronic products for off-grid solar power system and solar street light system. In addition, Bruhat Energy is also engaged in the installation and service of solar power system, solar street light system and solar pumping system. For more information kindly visit: https://www.bruhatenergy.com/