Introduction

While we talk about DER (Distributed Energy Resources), this concept is in continuous discussion in recent years across the electricity market worldwide. What is DER?DER is a digitally integrated small or medium-sized power resources that are installed directly near the point of consumption and also can potentially provide power to the grid. 

Solar on the roof, a clean energy solution for the mass people. This could be the main power resource for DER in rural as well as in urban India.

What is DER

DER comprises distributed generation (mainly solar or micro wind or hydro), storage batteries behind the meter and load control mechanism to run household items, smart charging of EV and power-to-heat ( explained later).

The modular nature of DER allows to build it up on any scale, from a single solar PV panel mounted on the top of a small hut in the village to a million solar PV panel set up mounted on the rooftop of a factory. 

Some usage of DER is described in the figure below.

Distributed Energy Resources
Image by Debasis Gupta

Behind the Meter Battery: As I mentioned before, small batteries are connected at the consumption point. These batteries store the surplus power during the daytime and release it during the night or whenever required.

Smart Charging of EV: EV charging cycle can also be sync with the power availability and that way optimizing the power use. For example, during midday when the solar generation is maximum, EV charging can be scheduled to utilize the extra generation.

Power to Heat: Residential purpose heating of water or other usages of hot water for various purposes in the industry like thermal boiler, heat pumps, thermal storage etc. can be done.

Demand Response: This process allows the consumer to choose the power source whenever needed, either directly from rooftop solar or from battery storage otherwise from the grid according to his requirement and availability of power in the respective sources.

 A consumer can also divert any excess power generated from rooftop solar to the power grid when he/she does not need it.

Distributed Generation: This system supports the ‘demand response’. Generation from many rooftop solar plants or micro wind turbines gets connected to the low and medium voltage local grid and distributed across the service area.

DER Present Status

In the recent past, DER was a very much talked about subject in the global market. Experts were foreseeing it as the next big thing to happen in the renewable market, but somehow it couldn’t take off finally as expected. 

Though companies like SolarCity in the US could achieve some initial success and still some more developers are present in the market to promote DER, however, in India (particularly) DER couldn’t penetrate much till now because of clear commercial reasons.

In India DER  is a necessity for multiple reasons like:

Job Creation in rural India.

Equitable, comprehensive and accessible power supply for people.

Better distribution efficiency.

Better grid reliability.

Better power supply for agricultural and rural people.

DER Concepts

There are different types of DER. One is complete isolation from the regional electric power grid. It is a combination of a rooftop solar system and a battery bank. The battery bank stores the power for night use or to use on a cloudy day. This model could be suitable for remote villages in India.

The limitation of this system is that it has no access to the regional electric power grid. Therefore, it becomes ineffective when there is no sufficient sunlight available during rainy days.

Moreover, in case of a fault in the system, in remote areas, repairing service may not be available on the same day eventually, there will be no power available for the consumer till the time system is restored. 

Though the installed battery bank can supply power in that situation, it can practically supply for a couple of hours only owing to its limited storage capacity. 

To overcome all these weaknesses of off-grid DER, a more practical version has been designed. In this, the rooftop solar system (or micro wind turbine) gets connected to the regional electric power grid. 

Whatever energy the solar (or wind) system can generate, if that is not sufficient enough or in case of a technical fault, power is drawn from the regional grid for consumption. On the other hand, there is to storage battery combined in this version and any excess power generated by the rooftop solar (or wind) system is fed back to the regional power grid. This way it is a more effective and balanced version.

Grid connected DER
Image: House vector created by brgfx – www.freepik.com

DER Potential in India

DER is carrying a good potential in India within a wide variety of applications. 

  • It can be used in residential buildings in the urban area,
  • in industrial and commercial facilities and 
  • finally in the rural part of the country where the grid is either not available or weak.

Combining these three areas there is a sizable potential of DER deployment that can take a considerable role in India’s target to emission reduction and climate mitigation.

A very conservative calculation shows that at least 15 GW DER capacity potential is available from rooftop solar in urban India. 

And how much GHG emission is possible to reduce with this 15 GW solar DER capacity? 01 GW of solar capacity addition allows phasing out of 0.3 GW of thermal energy production capacity. We know from research that 0.3 GW of thermal energy emits 1.4 million tonnes of GHG (greenhouse gases) annually.

So, 15 GW solar DER addition can cut off an impressive 20 million tonnes GHG emission per year.

The rural off-grid potential is another opportunity. It essentially serves the people at the bottom of the pyramid. A major chunk of those population lives in remote villages away from the quality power supply. 

Though in India, almost all of the villages have been connected to the regional grid ( barring some villages in a couple of states), but that doesn’t mean they get a continuous power supply for 24 hrs. Not even for 10-15 hrs in a day.

Voltage drop is another issue. I have experienced it in my life at some point in time. Even when a power supply is there, the supplied voltage is so low that it is practically impossible to use this power for any purpose.

Today roughly 500 million people in India or about 100 million households don’t get a reliable electricity supply in terms of power quality or supply continuity. They still use Kerosene Lamps for lighting, firewoods for cooking and diesel generator sets for irrigation purpose. We know, all of these are contributing to air pollution and also severely damaging the health of the users.

Now, let us assume that 80 per cent of these households are roped in under the network of an off-grid generation system and only a single solar panel of 300 Watt is installed on each roof. 

Can you guess what would be the total installation capacity of this network? Roughly 24 GW. That is the opportunity I was mentioning earlier.

We can summarise India’s DER potential as about 15 GW in the urban area,22-24 GW in the rural area, 27-30GW in the MSME sector and 30-32 GW in industrial sectors. 

In total, more or less 100 GW DER potential is readily available. Once explored, this can successfully reduce the country’s GHG emission by about 145 million tonnes per year.

Urban DER
Image: House vector created by brgfx – www.freepik.com

Present Status

Even though there was good growth in 2019, but DER (including off-grid and rooftop solar) did not continue at the same pace afterwards.

At this moment, it is accounting for about 5 per cent of the total installed RE capacity of India and a meagre 1 per cent of total installed power generation capacity.

Unfortunately, the growth is very slow in the DER sector. Investors are not interested and prefer to invest in big-ticket projects in general. DISCOMs are also not showing interest in fear of losing market share and profit margins.

There are some commercial complexities also awaiting resolution to make it a profitable business proposition in the poorer consumer sector. 

However, India needs to realize DER potential in near future despite all hurdles. More sooner is better.

Reference: Sinha, S.(2020). Fossil Free. Harper Business.