Blog Archives

Advanced String Monitoring System of today

What happens when a module fails in a 1-megawatt photovoltaic system, bringing down a 3-kilowatt string?

If the monitoring system tracks production for each of the two 500-kilowatt inverters, the loss of output will only represent 0.6 percent of a 500-kilowatt array’s capacity — virtually impossible to detect, especially when pyranometers commonly used in utility-scale PV plants measure solar irradiance with a +/- 2 percent uncertainty (or more). Even comparing the output of both inverters would hardly allow detection of the fault: inverters measure power output with a relatively high uncertainty (typically +/- 1 percent to +/- 5 percent).

Arguably, even multiple string failures could go unnoticed until the next inspection when maintenance technicians perform systematic string testing.

In order to quickly detect such failures and minimize the associated energy losses, some PV plants are equipped with string monitoring equipment. This consists of “smart combiners” collecting current (and sometimes voltage) for a string or a small group of strings, and sending this data to the monitoring system where some software analyzes the information and identifies low production string conditions.

String monitoring is a common practice in most European markets, along with string inverter designs for PV systems, which intrinsically provide the ability to monitor at the string level, since each inverter is a string or a small group of strings. In a recently published report about global PV monitoring markets, GTM Research and SoliChamba Consulting estimated that 100 percent of new utility-scale PV plants in Germany in 2012 were string-monitored, along with 95 percent of large commercial systems and 85 percent of small commercial ones (including plants with string inverters).

In other parts of the world like the U.S. and Japan, however, very few PV plants are string-monitored, even in the utility-scale segment. In those markets, the dominant perception is that string monitoring significantly increases the initial cost of the PV system without providing enough yield increase to justify such investment. No independent study has either proved or disproved this theory, and opinions may vary between EPC firms and project developers.

In order to better understand the logic behind this different approach, let’s examine the economics of a broken “3-kilowatt string”. Assuming that the average annual yield is 1,500 kWh/ kWp and the faulty string goes undetected for six months (until the next inspection), the lost production would amount to 2,250 kilowatt-hours. For a 2006-built German plant benefiting from the 40 euro cents feed-in tariff, this would represent a $1,200 loss. For a 1-megawatt system, the additional cost of string monitoring equipment ranges from $10,000 to $15,000, which is the equivalent of $500 to $750 annually over a twenty-year time span (excluding financing costs and installation, which is usually part of overall EPC budget). In these conditions, an average of one string failure per year would justify the investment. For a U.S. plant with a PPA (Power Purchase Agreement) price of 10 cents, however, the same production loss would only be worth $225, so it would take two to four annual string failures on the same 1-megawatt array to justify the investment. This simple calculation goes a long way toward explaining the gap in string monitoring adoption rates between Germany and the U.S.

In the past few years, a new DC array monitoring practice emerged in America, referred to as “zone monitoring” or “sub-array monitoring.”

By collecting sub-array data from the master combiner, zone monitoring provides an intermediate level of granularity for issue detection and diagnostics, at a much lower upfront cost than string monitoring ($3,500 to $5,000 for a 1-megawatt plant). With this approach, the ability to detect subtle issues is more limited, and the guilty string cannot be specifically identified — it is only possible to single out the sub-array that is underperforming because of it. In the case of our previous example, if each 500-kilowatt master combiner includes 15 sub-arrays (for a 33-kilowatt individual capacity), the loss of a 3-kilowatt string represents a 10 percent reduction of the affected sub-array’s capacity — an easily detectable anomaly. GTM Research and SoliChamba Consulting estimate the adoption of DC monitoring in the U.S. in 2012 at 65% in the utility-scale segment, 25% in the large commercial segment, and 15% in small commercial. Most of it is believed to be zone monitoring.

As often in the solar world, the ultimate decision to adopt a technology lies in the hands of the investors and their technical advisors. In Europe, these firms often mandate string monitoring for large-scale plants, and will consider a PV system less valuable if it does not include such monitoring capability. In the U.S., few solar investors have a strong opinion on this topic, and independent engineering firms that validate the production estimates used in financial calculations do not consider any difference in output whether a plant is a monitored at the inverter, sub-array or string level. In such circumstances, project developers and EPC firms are unlikely to invest in string monitoring technology.

Over time, as more data becomes available about module and string failure rates, we can expect the choice of monitoring approach to become less cultural and more financial.



Solar energy sector speeding in Karnataka


From the time when the government introduced a solar energy policy (2011-16) solar sector is on developing ride in Karnataka.

According to a report Renewable Energy prepared by PwC, which was released at the conference on ‘Sustainable Energy Through Renewables’, organised by Confederation of Indian Industry (CII), here on Wednesday, Karnataka is the only state to have supported solar projects under the REC (Renewable Energy Certificate) mechanism. Close to 950 Mw of project proposals have been submitted to Karnataka Renewable Energy Development Ltd (KREDL), which are under different stages of implementation like preparation of DPR.

Marvellous progress has been made by Karnataka in solar sector. Already it is having 14 MW installed capacity,  and over 1.2 GW  in the pipeline under various schemes. The 14MW installation is done under  Arunodaya programme by Karnataka Power Corporation Ltd. Of these 3 Mwp each are in Kolar, Belgaum and Raichur and a 5 Mwp in Mandya district in Karnataka. Based on report submitted to CERC in 2010, the energy produced by the 3 MWp in Belgaum was around 3.9 million units.

In a recent bid the government has allotted projects for 80 MW (60 MW for solar PV and 20 Mw for solar thermal) at tariffs between Rs 7.94 to Rs 8.50 per unit for solar PV and  between Rs 10.94 and Rs 11.32 per unit for solar thermal projects.

Karnataka is having one of the highest potentials for renewable energy among all states in India. Renewable sources are contributing to around 24% of the state’s installed capacity. If minor changes are done in the policy framework, Karnataka may come in the top 3 states in terms of annual wind capacity additions. Investors are attracted by the large untapped wind potential and above average wind.

Estimated renewable energy potential is 28 GW. As per the report a total of 17,278 MW, has been allotted from wind, small hydro, co-generation and biomass sectors which is nearly 60 per cent of the full potential. Of this, 2,016 MW is from wind, 88.5 MW from biomass, 948.7 MW from bagasse co-generation, 646 MW small hydro and 14 Mw of solar power have been explored. Most of the sites are far from grid. There is therefore a need to develop a robust and reliable transmission system for extracting the renewable potential. This will definitely help develop Karnataka as a leader.

(Source: Business Standard)


Generation of Power under JNNSM


India has separated targets for 2013 1100MW of grid connected & 20,000 MW by 2022 under the JNNSM, this information was given in written by Dr. Farooq Abdulla the Union Minister of New and Renewable Energy in Rajya Sabha, and the total investment may be approximately $ 40 billion for 20,000 MW of solar power projects.

205340.26 MW is the current installed generation capacity of India which includes

  • 24832.68 MW generated through renewable energy sources.
  • JNNSM aims at achieving 20,000 MW by 2022 thereby it will then constitute one-tenth of India’s current installed power base.
  • The total installed capacity in the country is likely to be more than 400 GW by 2022.
  •  Installed solar capacity then would be one-twentieth of the then India’s total installed capacity.
  • The share of renewable and particularly solar in country’s energy mix would keep increasing and would certainly help in limiting reliance on coal and easing the power deficit.

1030 MW of solar power projects have been commissioned and connected to grid  against a target of 1100 MW of grid connected solar power by 2013, and  these are under both Central and State initiatives according to theThe Minister .

Followings are the steps which are to be taken and the issues to be handled for the completion of the target and projects under the JNNSM by the Govt. & other respected departments

  • like up gradation of transmission network,
  • availability of unallocated power for bundling,
  • delay in payment by DISCOMS,
  • Weak State Nodal Agencies are being focused on.
  •  A transmission network up gradation plan has been prepared by Power Grid Corporation of India Limited.
  • Ministry of Power has been requested for giving unallocated power.
  • Payments from DISCOMS are being monitored continuously and States are being requested to upgrade Nodal Agencies.


All the above information tells us that there are serious steps which are to taken seriously for this growing industry to flourish and for the India to be a Major Player in the field of renewable energy.

(Source: India Power Sector)


Booming time for Solar Power in midst of worst blackout of the decade

This is the milestone for the Indian renewable energy sector as the sector has more than 1GigaWatt of solar photovoltaic power installed in India. This is in the data released by Ministry of New and Renewable Energy (MNRE).The announcement which came when there happens to be the worst blackout in more than a decade in the country with at least 300 million people affected.

In fact, the gap between electricity supply and demand is about 10%.
This blackout has slowed the developing nation’s economic growth. As India relies on coal for two-thirds of its power generation. Because of corruption and weak policies the government-based group struggles to meet electricity demand.
According to the experts these electricity shortages in India have created an opportunity for solar energy as the solar is the only solution for these blackouts and to the pollution creating processes.

Their efforts have already caused solar prices to drop, and experts believe that it might achieve price parity with coal as early as 2016.
The MNRE’s target was 800 MW of installed capacity by the end of 2012, but the nation had already surpassed this goal by the mid-year mark this shows the extreme hard work done by MNRE.

Solar capacity in India has almost doubled in just two months published in the report by the Natural Resources Defense Council and the Council on Energy, Environment and Water which is based in New Delhi.
There is sharp improvement in the output of the solar mission as the according to fact, only 17.8 MW of solar were installed in the country in early 2010,which shows the significant impact of National Solar Mission‘s on the market.

The price of solar energy in India dropped to as little as INR 7.49 per kilowatt hour or USD 0.15 USD/kWh just in Between early 2010 and March 2012 or say in two years only and major part of this price decrease is due to the reverse auction bidding process by National Solar Mission and also awarding solar projects to companies with the lowest asking price. This price drop in Indian solar power supports the future prediction that solar could achieve price parity with coal or natural gas by 2016.

This is also good for the employment sector as this resultant growth of solar capacity in India has and will add job opportunities for solar installers and manufacturers.

Lack of skilled labor remains a barrier to solar growth in India reported by the NRDC and CEEW. This means that those professionals who have or seek solar installer training and certification would find it easy and productive in applying for solar installer jobs in India and will surely have an advantage of this.

There are efforts in this field by the Governments to have skilled personnel and trainings etc. for this booming solar sector.

(Source: Steel Guru)

Solar industry insight

In 2011-12, India’s solar power capacities increased to nearly 940 MW from 20 MW in 2010-11.This is mainly due to the Gujarat State Solar Policy and the Centre’s Jawaharlal Nehru National Solar Mission (JNNSM) which are due pillars of  solar power development in India. Besides, a sharp decline in capital costs over 2011 also drove this rapid expansion.

Capacity additions

State Electricity Regulatory Commissions (SERCs) have mandated their respective power distribution companies to procure solar power. This is at a minimum of 0.25% as part of their solar renewable purchase obligations (RPO). Higher cost-reflective tariffs have supported the four times costly solar power over the conventional power. The central and Gujarat policy have facilitated long-term off take agreements for solar power. These are in between project developers and distribution companies (discoms) at cost-reflective preferential tariffs.

Globally, capital costs in PV (photovoltaic) projects) prices crashed due to massive capacity additions by China. Atop it, demand in key European markets — Germany, Spain and Italy — also dried up. This further reduced the module prices. Globally the demand stood at 25-30 GW solar photovoltaic (PV) module capacity compared to 50 GW at the end of 2011.  As a result, capital costs fell by 30% over 2010 level, to Rs.10 crore per MW by end-2011.

Still due to the continued over-capacity in global markets, capital costs are expected to decline to Rs.8.7-9 crore per MW in 2012. This comes to 12% decreased compared to the previous year. The pace of decline in module prices will slow down in 2012 as module suppliers in the U.S. and Europe are staring at eroding profitability, and even bankruptcy in some cases. Further, the weak rupee will limit decline in capital costs, as most of the equipment has to be imported.

The scenario of decline in the capital costs led many solar power producers to bid aggressively in the batch 2 of JNNSM  (350 MW bid out in December 2011). This brought a decline of nearly 25 % (at Rs.8.8 per unit) in the average tariffs bid, compared to JNNSM batch 1 (150 MW bid out in December 2010). However a levelised tariff of Rs.9 per unit is necessary for healthy return. In batch 2 of JNNSM nearly half the bids are below Rs.9 per unit and about a fourth bids are below Rs.8.5 per unit. This had made these investments highly risky.

Reducing borrowing costs is the throttle point for the viability of these projects. However, access to lower cost foreign funds is linked to foreign equipment supplies through developmental financial institutions. It will be thus difficult for the players opting for crystalline PV technology in phase 2 to tap these funds as they are required to procure crystalline PV equipment domestically.

If the low-cost foreign funds have to be accessed, the thin-film technology, on which the restrictive domestic procurement clause is not applicable, needs to be used.

Gujarat’ s solar policy is separate in this regard as there is no domestic content clause under it. The tariff of Rs.10.37 per unit offered under it therefore provides more attractive returns for project developers. There is also a strong upside to these returns as players can obtain cheap foreign debt. It can be therefore said that the extent of decline in capital costs will decide the momentum of future capacity.

(Source: The Hindu)

Solar energy crossing GW capacity

The data made available by MNRE now shows that solar PV installations in India have crossed the 1000MW or 1 GW capacity.

Grid interactive solar PV installed capacity was 1,030.66 MW by the end of June. Most of the capacities have come in Gujarat. Local use of solar energy has also undergone much height. The figure shows that India has 85.21 MW of off-grid solar PV systems with system capacity of at least 1KW.

Talking of the overall renewable energy installations in India total grid interactive renewable energy installations crossed 25,000 MW in the first quarter of the current year.

During the first quarter of the year, 291.7MW of the 495MW added was from wind energy sector in the first quarter of the year.

At present the total installed capacity of renewable power plants in the country is 25,409 MW.

Target for 2012-13

The Ministry has set a target of 4,125 MW of additional green power capacity for the current financial year. This includes 2,500 MW of wind power and 800 MW of solar PV.

It is worthy of note that the targeted wind power capacity is lesser than the achievement of last year, which was 3,164 MW.

When noted the views from the wind energy sector that even 2,500 MW would be a tough target to achieve, due to two reasons. The reasons being counted are removal of two key benefits i.e. ‘accelerated depreciation’ and ‘generation-based incentive’. The tough operating condition in the chief operating states like Tamil Nadu is also seen as a barrier for achieving the targets.


Hugh boost to the renewable energy inverter market with an estimate installation of 290GW till 2017

Some good news for the renewable energy inverter manufacturers and suppliers as the market for the inverters is on a boom as given by a report of Pike Research. According to the report the market of inverters for renewable energy market was $7.2Billion in 2011 and it is expected that the gross sale of inverters will be more than doubled crossing $19Billion in the next 5 years.

According to research analyst Dexter Gauntlett ” people have seen a vast drop in the prices of the solar modules affecting the market so avoid that situation to happen with the inverter market manufacturers have to reduce the cost along with increasing the functionality and should differentiate themselves from others. Big manufacturers such as SMA, Power-One, Satcon, KACO, Fronius have advantages of the size and their market reach but even the new companies and small-scale companies are coming up really fast with new innovations and technological advancements.”

As the report suggests Europe will continue to be the global leader in the installed inverter capacities for the next several years with 47% of all the renewable energy inverter capacity installed through 2017, led by solar PV inverters. Also around 72GW of inverters will be installed in Asia-Pacific in comparison to 66GW in North America. It means nearly 290GW  capacity of inverters will be installed worldwide for four primary technologies – solar PV, stationary fuel cells, small wind power and vehicle to grid enabled vehicles int he next 5 years.

(Source: Solar Industry Magazine)

Government planning to level the solar field for domestic developers

Government is now moving to help out the local manufacturer from clutches of the imported solar equipments.

The government is expected to make changes in the equipment sourcing policy before the starting of bidding under JNNSM phase II, which is going to bring in investment of Rs 1.08 lacs crore.

According to sources the officials from ministries concerned such as MNRE, power and finance as well as the Planning Commission met last week to discuss changes in existing bidding guidelines for solar mission projects. The MNRE ministry may seek feedback from financial institutions, project developers and equipment manufacturers, besides NGOs on anticipated changes.

Although the share of thin film –PV is 12-13% but it is expected to be 60-70% in Indian context. Therefore the government is alarmed at the surge in demand of thin film technology equipments due to its comparatively lower efficiency, although at lower prices.

This is instep of levelling the field for domestic player. Already Moser Baer, the sole Indian manufacturer of thin film modules had shut down its plants. “Bringing thin-film solar modules under the domestic content requirement would help level the playing field for solar PV equipment manufacturers,” said Prasanth Sakhamuri, chairman, HHV Solar, a Bangalore-based company.

But according to Mr. Tarun Kapoor, joint secretary, MNRE “The government is likely to be neutral on technology for solar mission projects”.


(Author: Rochit)

(Source: Financial Express)

The new REC price band as revised by CERC

The Central Electricity Regulatory Commission(CERC) has announced the floor and forbearance prices to be used for solar/non-solar projects from the FY 2012-13 upto 2016-17. The prices set are shown in the table below

Non Solar (Rs.) Solar (Rs.)
Prices (2012-2017) Current % Reduction Prices (2012-2017) Current % Reduction
Forbearance Price 3300 3900 15.38 13400 17000 21.18
Floor Price 1500 1500 0.00 9300 12000 22.50


Earlier, the CERC had proposed a few changes (refer table below) to be made to the REC prices and invited comments/suggestions on the same.

Non Solar (Rs.) Solar (Rs.)
Proposed Current % Reduction Proposed Current % Reduction
Forbearance Price 3480 3900 10.77 13690 17000 19.47
Floor Price 1400 1500 6.67 9880 12000 17.67


The final prices to be enforced from April 2012 were arrived at after considering the comments/views of stakeholders and participants at the public hearing on the proposed floor and forbearance prices. As can be seen, the final prices decided upon are considerably lower than the earlier proposed prices.


Financial feasibility studies of power plants under the REC mechanism almost always consider the floor price for calculating returns. With this in mind, the evaluation of REC for the primary renewable energy generation systems looks quite healthy.

  • Non-solar – the floor price remains unchanged. Thus biomass/wind generators are expected to get the same minium revenue as they have been getting earlier.
  • Solar – the floor price has seen a cut of about 23% from current levels. Although this might seem drastic, it is not likely to have a significant impact on solar power projects (refer section below).


APPC – Non preferential tariff and REC

CERC stipulates that for a project to be eligible under the REC mechanism, the power producer has to sign a PPA with the state utilities at a price equal to the APPC price. The APPC price for a state for a particular time period is determined by the State Electricity Regulatory Commissions(SERC).

Looking at the current APPC prices in various states, a combination of REC and a PPA signed at APPC rates seems comparable with the preferential PPAs signed with the state utilities.

For example,  let us consider a solar PV plant to be setup in Tamil Nadu where the APPC price for 2011-12 is Rs. 3.38/kWh. Under REC regulations, if a RE developer were to get the floor price for the solar REC, the income for the solar PV plant would be Rs. 12.68 /kWh (Rs. 3.38 + Rs.9.3). Another case is Rajasthan, which has a very high potential for solar PV – where the income would be Rs. 11.9 /kWh. In comparison, under the phase 1 (batch 1) of JNNSM, the average price settled on through the reverse bidding process was  about Rs. 12.5 per kWh.

As can be seen, these prices are comparable to tariff set through reverse bidding under batch 1 of the JNNSM scheme.

Prices can only go higher

APPC prices are set based on the cost of power generation from fossil fuel based power plants. It is highly likely that this price would increase in the future due to the increase in fossil fuel prices and scarcity of supply. This ensures that the APPC prices would continue to increase for the foreseeable future, thus ensuring higher year on year returns under the REC mechanism provided the PPA signed with the state utilities has provisions for purchase at floating APPC prices rather than fixed price.

The table below gives a comparison between preferential tariff (reverse bidding under JNNSM) and REC mechanism for a plant in Tamil Nadu. The following assumptions were made for the sake of calculations

  • Average bid price under phase 1 batch 2 of JNNSM could be around Rs. 12.5 /kWh(on the higher side)
  • APPC prices could rise by 15% annually (base price used is that of Tamil Nadu) – reasons for this were mentioned earlier.
  • REC price after 2016-17 period (i.e. from FY 2017-18 onwards) is reduced by 25%


Year 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021
JNNSM Tariff (average) (Rs. per kWh) 12.5 12.5 12.5 12.5 12.5 12.5 12.5 12.5 12.5 12.5
APPC (Rs. per kWh) 3.38 3.89 4.38 5.04 5.38 6.19 6.38 7.34 7.38 8.49
REC (Rs. per kWh) 9.30 9.30 9.30 9.30 9.30 6.98 6.98 6.98 6.98 6.98
Total (Rs. per kWh) 12.68 13.19 13.68 14.34 14.68 13.16 13.36 14.31 14.36 15.46
REC mechanism’s Incremental revenue over PPA(Rs. per kWh) 0.18 0.69 1.18 1.84 2.18 0.66 0.86 1.81 1.86 2.96

Table: REC vs preferential PPA for 10 years post 2012



As can be seen from the above table, the REC mechanism is quite comparable, if not better when compared to the assured tariff provided by NVVN over 10 years of operation of the solar powerplant. Overall, the REC mechanism can clearly drive the solar market, provided the Renewable Purchase Obligation (RPO) is strictly enforced by the various SERCs.


(Author: Suman)

Booming solar market expects grid –parity in very near future

Our capacity increased to 940 MW in 2011-2012 from just 20MW in 2010-2011. But why is such a sudden change? It is because the component which consumes half the cost of projects i.e. –panels, has cut down it’s price by 30% in  last year. It already showed a decline of 80% in the past 5 years. According to a CRISIL report “Capital costs fell by 30% from a year ago to Rs 10 crore per MW (megawatt) by the end of 2011. The fall was driven by 50% drop in prices of solar PV modules, which account for almost half the capital costs of a PV project. The sharp fall in capital costs has improved the returns from the projects that were commissioned in FY12”.

A latest report by Pew Charitable Trust says that the flow of private investments into the country’s solar sector has already seen a seven-fold jump to $4.2 billion in 2011.

But one crucial analysis from all this is that grid parity is very nearby, i.e. the cost of power from solar is on a par with the cost of power from new coal, wind and hydro-based plants. “If we compare the cost of power from new coal-based plants, it will be at par with that of solar. If one takes into account the total duration of the power purchasing agreement, which is 25 years, grid-parity is already there. Solar power needs only a one-time investment in the form of land and PV panels. Its fuel, which is sunshine, is free unlike coal where price will head only northwards,” said Gaurav Sood, MD, Solairedirect.

The reason for declining panel prices are heavy subsidies by China to its domestic manufacturers & recent reduction of subsidy to the sector by Germany, the largest solar power generator in the world.

But this has pressurised our module manufacturer, to compete with Chinese markets. This subsidy by China has already swallowed many leading global manufacturers such as Solyndra (US), Q Cells and Solar Millennium (both in Germany) which have filed for bankruptcy.

But the funding banks are still awaited for becoming open to solar sector. They are still reticent about still rock-bottom tariffs and higher debt levels. “We are keen to assist solar projects as they are pollution free. But we would prefer a lower debt-equity ratio in the range of 60:40,” said B K Batra, executive director, IDBI Bank. Other banks now financing for this sector are US EXIM bank, ADB and IFC


(Author: Rochit)