Feb 27, 2015

Design your own solar power system : For Individual Home Owners

We can design a residential solar system by ourselves. For this one needs to know what a solar system is made of. The basic components of the system are:

  • Solar Panels
  • Charge controller
  • Inverter
  • Battery
The whole designing of the system is based on the energy consumption of the electrical appliances that need to be powered by the solar panels.
The step by step procedure of designing the system as follows:
Determine the Power consumption demand:

Let us take an example, in a house there are 4 CFL of 18 watts which operates for 4 hours in day ( though it is always better to use LED to save and reduce load, but the fact remains that CFLs are more prevalent and used in todays time - our experience and research shows that residences are shifting to use of LED bulbs and fixtures and the new buildings being made are preferring LED technology).

Two 80 watt fans used 4 hours in day and
1 television of 150 watt operates 2 hours in day.
Now, the total appliances usage in watt-hours :
CFL: 4 no’s x 18 watts x 5 hours = 360 watt-hours/day
Fans: 2 no’s x 80 watts x 4 hours = 640 watt-hours/day
TV: 1 no x 150 watts x 2 hours = 300 watt-hours/day
Adding all the above values,
(360 + 640 + 300) watt-hours/day
1300 watt-hours/day
This is the daily energy requirement that needs to be backed by the solar panels.
Sizing the PV panels:
Energy required from the solar panels = 1300 x 1.25(as some of energy is lost in the form of heat)
                                                               = 1625 watt-hours/day
Now, divide this value by the solar insolation for that area where the system is to be installed to get the peak wattage of the solar panels.
(The average solar insolation New Delhi is 5.5 KWhr per square metre daily but you would typically get about 5 units of solar energy production every day)
=325 watts
Therefore, number of 120 watt panels needed: 3 no.s

Inverter sizing:
The total watt of the appliances is
CFL: 4 no’s x 18 watts = 72 watts
Fan: 2 no’s x 80 watts = 160 watts
TV: 1 no x 150 watts = 150 watts
Adding all the three values, 72 watts + 160 watts + 150 watts we get 382 watts.
For safety purposes the inverter should be at least 25%-30% bigger in size.
Therefore, the rating of the inverter should be 382 x 1.3 = 496.6 watts or greater.

Sizing the batteries:
Calculate the total wattage of the load (as calculated above) = 382 watts
Divide this value by 0.8(battery loss) = 382/0.8 = 477.5 watts
Divide this by 0.8 (conversion loss by inverter while converting current from dc to ac current) = 477.5/0.8
 = 596.87 watts
Divide this by 0.7 for the depth of discharge (for long life don’t fully discharge the batteries, keep 30% charge remaining in the batteries)
= 596.87/0.7 = 850 watts
This is the amount of energy which is required from the batteries to run the appliances.
Now let us suppose that backup required from the batteries is 5 hours.
Multiply 850 watts by 5 hours, we get  watt-hours which are required from the batteries.
Now, divide the result by 12 volts, the nominal battery voltage, to get the capacity of the battery, we get 4250/12 = 354 ampere-hours.
So, the battery should be rated 12 volts 354 Ah for 5 hours back up. Or one can even plan for a 24 V system in which case, the Ah capacity would be half of 354 Ah.

Sizing the solar charge controller:
The rating of the charge controller = total short circuit current of the PV array x 1.3
The 120 watt PV module specification is:
  • Power in watts (Pm) = 100 watts
  • Open circuit voltage (Voc) = 21 volts
  • Short circuit current (Isc) = 6.95 amperes.
  • Voltage at maximum power (Vmp) = 17 volts
  • Current at maximum power (Imp) = 6.18 amperes
We assumed that the solar panels are arranged in the parallel combination. The current will get add up i.e. 6.95 x 4 = 28.4 amperes. Therefore, the rating of the solar charge controller is 28.4 x 1.3 = 36.92 amperes.
So, the solar charge controller should be rated 36.92 amperes at 12 volts or greater. You would typically get a 40 A rating charge controller in the market.

This is the basic designing that one can do oneself and evaluate the cost of the system based on the specification of the components.

Financing Solar in India : 7600 MWs added every year

There are close to 171 banks operating in India with 76,000 branches and over 12,000 NBFCs. There is already talk at the Central Ministry level of financing solar via the bank branches and the Regional Rural Banks. Initial meetings and top level honchos have met, with the MNRE officials, and they have been mandated to send the message downwards to the branches. While things are yet to change at the branch level, one often wonders ......What if each bank branch was mandated to finance 100 KW of solar power each year. Where would this lead us ?

The plain arithmetic of this is mind boggling !

7,600 MWs of solar power added to the country's capacity every year and the biggies have not even stepped in.

Is 100 KW difficult to finance ? Not really, if we consider an average sized branch - it can benefit from about 8-12 KW of SPV plant itself for its own captive consumption. With each branch catering on an average to around 1800 customers, being able to offer this proposition to 20 customers of this lot, should not be difficult since the bank would have access to repayment capability. Financing this, would be in the bank's interests in any case ( even if its on preferential interest rates).

Imagine if this becomes policy or mandate for the next 10 years. Remember that grid parity can be achieved by 2017 according to experts, and we believe that timeline shall get crunched even more. So financing and offering this post 2016-17, should be a compelling proposition in any case.

Now, if this can provide 76,000 MWs of decentralised energy generation, this is equivalent to producing about 110,000 MWs via power plants and distributing (taking into account, various T & D losses).

Financing solar in India truly is the key to unlocking solar potential in India.

Feb 9, 2015

New Delhi : Power Scenario

This is an excerpt of w white paper on Delhi's power scenario going around, in social media, hence the views expressed here are not the ones that we subscribe to. However, here goes, since it makes for an interesting reading of the current scenario. With AAP, likely favorites to emerge, the scenario post New Delhi elections shall need some close observations as to how electricity rates are going to pan out.

Quote :
On January 10, Prime Minister Narendra Modi presented competition in power distribution sector with consumers having an option of choosing their power service provider as a solution to cut down power tariffs in Delhi. Discoms in Delhi have become private monopolies and introducing competition would indeed be a welcome move. However, oversimplified formulation of drawing a parallel between power and telecom is misleading and erroneous. While competition in electricity distribution will help in containing the electricity tariffs , it cannot be panacea for all the ills plaguing this sector as therer are very serious issues at various levels.

If things continue the way they are power tariff in Delhi will be around two and a half times in five years from now. The people of Delhi owe to power distribution companies—Anil Ambani owned BSES and Tata—Rs 11,432 crores with the carrying cost of 8 percent interest per annum. Another approximately 1500 crores of rupees is in the process of being approved by Delhi Electricity Regulatory Commission (DERC). In the existing policy and regulatory framework, there are only three ways to pay off the regulatory assets —(a) the central government provide funds to liquidate regulatory assest  (b) the Delhi government pays off the  discoms; (c) the consumers pay by way of increased tariff. Two years ago the then Delhi CM Sheila Dixit had tried exploring the first option but had failed. She had approached the then Finance Minister P Chidambaram to provide assistance under Accelerated Power Sector Reforms—a scheme by which Central government disburses grants for power sector reforms. The then  Finance Minister  had refused to grant the aid on the ground that the power sector in Delhi was already privatized while the scheme was meant state owned electricity boards. The second option is hardly feasible as the annual budget of Delhi government for 2014-15 is just Rs 36,766 crores, a little more than the budget of Brihanmumbai Municipal Corporation (Rs 31,178 crores). Its next to impossible for Delhi Govt to write off the Rs 13000 crores of discom debt. Hence the only way the discoms can recover their dues is by doubling or tripling the power tariff.

Imagine an average middle class family paying a monthly electricity bill of Rs 5,000 for roughly 500 units in a few years from now. The moot point is  how has the system allowed this situation come to pass? What were the regulators and the government doing? Why did the previous regimes didn’t order an audit of discoms and regulate the cost of power generation? The power policy followed by successive governments has failed in bringing in transparency in the functioning of various players. Everybody involved in the chain—from fule suppliers to power producers to transmission companies to distribution companies—have made money at the cost of hapless captive consumer- a common man . The beneficiary companies include both private as wells as public sector companies.

It is now well understood that  power producers with captive coalmines did not  pass the benefit of free coal to the end consumers. Power generators who were dependent on imported coal ,  inflated the cost  of coal imports thus not only siphoning the money abroad but also securing a higher power tariff. The Directorate of Revenue Intelligence in its recent investigations has pegged the overvaluation of the coal imports at Rs 29,000 crores between 2011 and 2014 alone.   This cost too has been paid by consumers.

The PSUs involved in fuel supply, power generation, and power transmission have also made windfall gains. The monopoly of Coal India has made it one of the most inefficient but ironically one of the most profitable and cash rich PSUs. Private players involved in the excavation, supply and benefaction (washing) of coal—mine operators, transporters, coal washeries—have earned undue profit in the process.  Several cases registered by CBI and reports of expert committees set up by the Supreme Court reveals massive theft of coal during the mining, washing and transportation process. It’s the end consumer who has been paying for this dishonest practice . Both Public and Private sector power producers show excessive coal consumption( by way of very high station heat rate) to show high cost of power generation resulting in unreasonably high tariffs.

The devil lies in the details. Power generators are charging unwarranted overhead expenditures in the name of administration, welfare, research and development, secondary oil consumption and maintenance cost, which cumulatively hike up the power cost. Investigations by DRI show that the capital cost incurred by some producers has also been artificially hiked manifold. According to reports the DRI is "investigating gross overvaluation of import of equipment and machinery by various entities of Adani Group from a UAE-based intermediary.” Like in the case of over-invoicing of coal imports, the over-valuation of capital equipment for power projects enables the power producers to, (a) siphon off the public money procured from PSU banks; (b)exaggerate its capital cost of power production.

The latest power tariff orders passed by DERC throw up very important  issues. The rates at which power generators are selling power to Delhi discoms varies between Rs1.2 per unit to Rs12.21 per unit. Consider this, the newly commissioned Sasan Ultra mega power plant which was awarded coal blocks under competitive bidding is selling power to Delhi at Rs 1.2 per unit. Reliance owned Sasan UMPP bagged coal blocks by bidding to supply power at Rs 1.196/unit. On the other hand Central PSU National Thermal Power Corporation, which have coal linkages with Coal India and which supplies about 75 percent of Delhi’s total power consumption, sells power at rates between as low as Rs 1.75 per unit to as high as Rs 6.15 per unit.  Similarly, NHPC plants supplies power at per unit rates varying dramatically between Rs 1.77 to Rs 12.21.  The issue is why Delhi does not have access to cheaper power and why it is being forced to buy expensive power ?

Unfortunately Delhi has limited captive power generation capacity resulting in its dependence of  external sources of power generation who profit at the cost of consumers. To contain ever increasing demand of electricity, it is imperative that Govt of NCT of Delhi sets up power generation plants either by itself or in collaboration with other players at most economical rates and locations.

Since Discoms earn an assured return of 16 percent (return on equity), they don’t care about the cost of power purchased they will be made  accountable in their functioning . Ways and means have to found to encourage distribution companies  to purchase power from economical sources and wriggle out of expensive and unsustainable Power Purchase Agreements.

The discoms in Delhi need to be told that before they could square off Rs 13000 crores of regulatory debt they will have to agree to an unconditional and thorough CAG audit. In the past the BSES has been penalized by DERC for goldplating its expenses and fraudulent practices. Individual instances of corruption and cost inflations lead to suspicion of a pattern in inflating expenses and thus warrant a comprehensive audit. Until that happens the Delhi Government will have to support the economically disadvantaged who are already reeling under high power tariff rates and any further hike would break their back. In addition the state of Delhi needs to promote solar power on a large scale and the concept of Green buildings.

A more efficient, transparent and accountable system to regulate and audit the power sector players  is inescapable The present mechanism of Electricity Regulatory Commissions too require a complete overhaul. The standing parliamentary Committee on energy in its report dtd 24.8.2012 presented in LokSabha  stated  “The Regulatory Commissions have become the refuge for the superannuated but influential officials. Their primary objective is to remain in employment rather than making any meaningful contribution with regard to the activities of the Commissions in the pursuit of their objectives. Hence these bodies have lost sheen and the authority, which they were designed to represent.” The opaque and arbitrary nature of the Commissions’ functioning have made them susceptible to extraneous forces. The fact that regulatory assets were allowed to accumulate since 2006 is a testimony of DERC’s failure. In the past one year alone power tariff in Delhi has been hiked by 15 percent. The total increase would have been 22 percent by now had the regulator not been forced to withdraw the order of November 14 hiking the power tariff by another seven per cent. DERC withdrew the order within 24 hours after the opposition launched a fierce attack on the Central Government and threatened to take to the streets.

Transco, the Delhi govt owned transmission company, is in a poor shape. Discoms have been irregular in paying Transco the wheeling charges. As a result Trasnco has failed to upgrade and enhance the transmission capacity leading to frequent power outages during peak demands in the summers. Delhi’s electricity scenario is a ticking time bomb.

Unless urgent corrective steps are taken to put in place a transparent and accountable mechanism to regulate unwarranted profit making by coal(fuel) suppliers, power generators, transmission and distribution companies, the people of Delhi will soon be staring at a power crisis of nightmarish proportions.