The Indian small-scale CSP manufacturer Sollector Systems is working on a dish concept that could work alongside traditional power sources such as diesel generation.

By Jason Deign

Could off-grid power give CSP a lifeline in an Indian market where grid-connected projects are struggling? So far the initial boom predicted for grid-connected CSP in India has failed to live up to its promise.

The alleged reasons for this lacklustre performance range from poor direct normal irradiance (DNI) data and a lack of components to the poor value of the country’s power-purchase agreements.

Many of these issues, such as DNI data and the availability of heat transfer fluids, now appear well on track to being resolved. But the experience so far appears to have dented confidence in CSP across the country.

Hopes that a new government led by the renewable-friendly Prime Minister Narendra Modi might kick-start investment in the sector need to be tempered with some fundamental challenges facing Indian grid-scale CSP, including its price differential with PV.

And the situation is not helped by the fact that several large CSP suppliers in the Indian market have either gone bust or abandoned the sector. The list includes Solar Millennium, Infinia and, most recently, Areva Solar. The off-grid sector might offer a different kind of opportunity, though.

According to 2012 renewable power ministry figures quoted by Reuters, about 40% of India’s 1.2 billion population has no access to grid power.

The government is backing distributed PV generation to give these citizens power, but some solar industry experts reckon CSP could yet offer better economics.

Based on a feasibility study using low-cost mirrors, vacuum-jacketed absorbers, an insulated concrete heat store and an organic Rankine-cycle generator, US solar entrepreneur Shawn Buckley reckons he could beat the current cost of PV and battery-based systems.

“I don’t know what the engine costs,” he admits. “My guess would be about USD$1 per watt for the gen-set. Utility-scale PV for solar farms is about $2 per watt. Costs are estimated to be close to $3 per watt for battery storage”.

Overall cost

“That’s $5 a watt total with only an inverter required to make AC electricity. We think this same mix of collector and storage to make AC electricity would have costs of $1.3 per watt, giving an overall cost of a third of the PV-battery solution.”

These are US market figures, of course. And Buckley cautions that they are “just off the top of my head.”

Nevertheless, such low-cost systems have the advantage of being relatively low-tech, which means much more equipment can be made locally and there is less danger of critical supplier or engineering, procurement and construction contractor pulling out and scotching the job.

“It brings local jobs to make the collectors and uses local contractors to make the heat storage,” Buckley comments.

Not everyone is convinced. Madhavan Nampoothiri, founder and director of RESolve Energy Consultants in Chennai, says: “I doubt if there is a business case for off-grid CSP in remote areas.”

He adds: “The concept of micro-grids hasn’t really caught on yet in India and there are significant challenges even for sub-5kW off-grid systems in rural areas.”

The scale issues Nampoothiri alludes to are exacerbated by the fact that the most obvious CSP technology for distributed generation, dish Stirling, has never really convincingly proved itself in the field.

Vendors were still stating the case for their systems last year, but since then news on new projects has been notable for its absence. Infinia, one of the early Indian market dropouts, was itself a dish Stirling provider.

Off-grid applications

Infinia’s assets were taken over by the Israeli Stirling engine maker Qnergy last November. Qnergy’s web site says the company has linked up with Abengoa for continuing development of dish Stirling systems for off-grid applications.

Qnergy did not respond to a request for further information, however. And even if such a dish Stirling system could prove to be commercially viable, without storage or a significant price advantage it would have serious trouble carving out a niche against PV in India.

That has not put off local CSP developers, however. The Indian small-scale CSP manufacturer Sollector Systems, for example, is working on a dish concept that could work alongside traditional power sources such as diesel generation.

“Our system is geared for distributed hybrid power generation and integrates well with compact thermal storage,” explains the founder, Raj Banerjee. “We are at a research and development stage and have built and tested our first prototype, which is currently in India.

“I feel this is probably the best prospect for CSP given the current situation with PV prices and the massive risk and capital entailed by large power plants.”

The ace up the sleeve for Indian developers such as Sollector is that local manufacturing has the potential to reduce CSP costs by up to 20% according to a World Bank report last year.

Admittedly that is for grid-connected plants, but let us not write off the value of a cottage industry for off-grid CSP just yet.