Cost Effective approaches for SPV Projects & Energy Efficient Equipment

Today’s power scenario in the world and in India in particular has changed from that of 'Generation, Transmission,Distribution' to 'Generation, Storage, Distribution & Effective usage'. Solar power generation especially at the last milestone has been recognised as the need of the hour and though, India has not woken up to the effective storage and efficient use of power, the world at large is seriously looking at these dimensions. - S V Rao

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Cost Effective approaches for SPV Projects & Energy Efficient Equipment

In this presentation, an attempt is made to investigate the nuances in SPV generation, Energy Efficient use, storage and localised Distribution of Power. Let us start looking at the numbers, starting from the tail end.


Lighting contributes to a major component of the use of Power in India, the national average stands at 22%. If we segregate the urban and industrial loads, lighting and pumping contributes to about 90% of the rural loads and, not being able to meet these demands often fell the political party from power and seat them in the opposition – for very valid reasons.

No surprise, the lighting load can be reduced by 60 to 70% by changing the bulbs and tube lights to LED lamps. Realising this and for Environmental goals, in America and Europe, the Utilities themselves offer the LED bulbs at huge discounts and with 3 years replacement guarantee. Let us study the economics of LED lighting as compared to the traditional units. It is in the light of these evaluations and for reducing CO2 emissions, the planners in the other countries have offered LEDs in open malls at subsidized rates.

What Can India and new States like Telangana Do?

Taking ground realities into considerations, it would be prudent to adopt a policy like:

I Provide 2 LED bulbs free of cost to all households with regular connection and whose monthly bill is less than say, Rs 500.
II Provide 3 LED bulbs free of cost to all households with regular connection and whose monthly bill is above 500.
III Provide LED bulbs at subsidised cost of
Rs 50 for all requirements above these free supply for consumers having legal connection subject to a maximum of
5 bulbs.
IV Provide LED bulbs at subsidised cost of
Rs 100 for all consumers other than III above.
V Collect Energy Conservation cess of 15% on all incandescent lamps, tube lights and CFL’s with PF less than 0.9.

Item IV above needs special discussion.

In item I and II we spoke about free supply of LEDs to regular consumers while, in Item III we are supplying another 5 bulbs at concession rate for legal consumers and in IV we are providing bulbs at less subsidised rates irrespective of whether he is a legalised consumer or not. Does it not mean that we are providing subsidies to illegal consumers also!

The ground reality is that, most of the lighting consumption in general and especially in non urban areas is from unauthorised consumers and commercial users. In general, for every consumer in I above, there are 3 to 4 consumers not falling in I. The Establishment cannot afford to miss this huge saving in this uncountable spent energy.

Moral of the Story

Without huge subsidy program, such a significant saving to the nation cannot be affected as a normal consumer looks for his immediate cash out but not the life cycle costs.

Issues Relating to Storage

Power is not available for supply to the houses in rural areas in the evening hours – a time when they want most. Even if available, the supply is erratic. Both such phenomenon cause irritation & nurses anti establishment sentiment.

Storing of power in the household just enough for the evening supply solves this problem as, power can reach the storage any time of the day/ night and kept ready for use in the evening hours. In India, as of now, the most convenient and reachable solution lies in inverter and battery storage – as discussed later in this paper. There are serious cost and maintenance/ replacement irritants in battery storage for some technical reasons. So, let us closely examine these issues & seek remedies for resolving them.

Requirement of Storage for a Simple Household

In a typical household seeking comfortable living, it is estimated that 2 light points and 2 fans are used for 5 and 10 hours each. These consume 2.15 units per day and with 15 to 20% inverter losses, the total consumption works out to abut 2.5 units per day.

The storage requirements and the wear and tear of the battery under the conventional & Energy Efficient systems are tabulated below:

It is known case that, many of the solar power installations and inverter household installations become dysfunctional because of the costs involved in replacement of battery every 3 years & the high rising costs of batteries. This has become a major irritant in the advancement of storage solutions. The Energy Efficient Lighting (LED) & the Energy Efficient Fan (Standing) can improve the life of the battery & to some extent, mitigate this problem.

Issues relating to Power Quality

As already mentioned earlier, the large incidence of inverters into the system can affect quality of power mainly because of harmonics. Therefore, there is a need for introducing minimum standards to be met by the inverters to avoid this disturbance in the networks. For this purpose, at the time of purchase, quality standards should be stipulated as below & type testing and strict quality control exercised.

In particular, the Harmonic distortion should be treated as essence of the inverter design.

If the inverter resolves the problem of lighting, is there a case for SPV power generation at the consumer’s end?

Case of solar home lighting system vs. Inverter

SPV power generation is very costly. Let us have a look at the present day costs of an SPV system with inverter and subsidies Vs. an inverter battery combine (for which has no subsidies are provided). It is clear from the Table above that, even with subsidies, the SPV system works out costlier to the consumer as compared to an inverter with a 3 hour standby.

In addition, the monthly cash out for the consumer for repaying the loan in the case of SPV works out to as high as Rs 300 for a 5 year period, an inconvenience he has to pay for while, his counterpart in uninterrupted urban and other areas enjoy low cost supplies.

Issues such as these and the need to change the battery every 3 years form a formidable road block for a massive take off in the case of SPV home lighting program.

‘Possible Solutions for Massive offtake of Solar Home Lighting Program – Feasible Within Regulatory Framework’. In the present scenario, the solar power from the SPV is neither measured nor, it is pumped into the system.

In the absence of stock taking, the number of SPV systems installed are only for “Statistification” (Statistical Satisfaction) that describes unaudited or un-monitored benefits as, on any evaluation, probably, only 10 to 15 % of the installations would be in operation (battery changing being one of the main irritants, electronics – the other).

On the other hand, if the units generated are measured and pumped into the system and the units are paid for, they ensure:

  • Income to the consumer.
  • Accountability as, the flow of revenue to the consumer leads to incentives.

The utility installed meter is a legal instrument and therefore acceptable to all role players.

The units accrue revenue to the utility at a rate of Rs 9.3 around. Taking the accrual to the SPV unit as Rs 7 (after retaining the rest for handling charges by the utility), the final payment to the SPV unit can be Rs 7 and APPC (Andhra Pradesh) of Rs 3.50 making a total of Rs 10.50 per unit. All these prices are already agreed to by the Regulators.

The inverter part acts as a standby for power shortages. Once, a sunlight sensor is installed, the inverter can be programmed to switch on the power to the house only after 6 pm so that, the peak evening load can be reduced and the consumer will be happy to get uninterrupted supply in the evening hours. During the evening hours of 6 to 9 pm, the consumer has 2 LED’s and one standby fan working for him apart from the other points in the house so that, even if power is not available in the evening hours, he still gets the comfort of lighting and a fan.

In short, the approach suggested:

  • Providing a SPV home lighting system of 100 wp with a C10 battery and inverter
  • The inverter having a sun light sensor that starts the supply at 6 pm
  • Providing 2 LED bulbs and one Energy Efficient solar stand fan free of cost to the consumer
  • Will instantaneously save 80 Watts or, Rs 4800 in investment on new Generation and Transmission,
  • Will reduce evening peak on the system,
  • Will provide evening lights and fans to the consumer in the villages.

In addition, the recurring saving in units work out to a huge sum of over Rs 12000 per unit installed over the life of the LEDs and SPVs.

This approach – which does not need any policy modifications and the only requirement would be for metering the SPV output and pumping the units into the network, triggers a massive uptake of the Solar Home Lighting systems to the advantage of the new states like Telangana and, to the Nation.

Suggested Implementation Plan

Inveter – Battery Combine for Evening Power

The Governments like Telangana, should come forward to encourage private investors to install Inverter and Battery combines by giving a subsidy of Rs 1000 per unit so that, they can formulate bankable projects for installation of such units in rural households. The consumer would have to make an upfront payment of say Rs 800 per month and monthly payments of about Rs 250 for a three year period for the purposes of financial viability to the investor.

SPV – Inverter – Battery Combine with Energy Efficient Lights and Fans

Likewise, the Government should announce a system of purchasing power from the SPV household units at a rate of Rs 7 towards REC and Rs 3.5 as APPC so that, the SPV household system program becomes a bankable proposition.

If you want to share any thought or feedback on this article then please leave a comment below.