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Solar-diesel hybrids beat PV and batteries off grid


08 July 2015 by

Recent interest in combining energy storage with PV overlooks the fact that solar-diesel hybrid plants are still usually the best option for off-grid power.


Solar-diesel hybrid system vendors are looking to grow off-grid market share despite growing interest in PV and batteries. Using solar panels to offset diesel costs is still usually much cheaper than using batteries to replace fossil fuels altogether, experts believe.

“I am convinced that storage is far too expensive to replace diesel at the moment ,” said Dr Thomas Hillig of Thomas Hillig Energy Consulting .

Volker Wachenfeld , executive vice president of the off-grid and storage business unit at the inverter maker SMA , chimed: “Even in the sunniest regions of the world, a pure PV-battery-hybrid system will be too expensive to ensure a 100% power supply."

“After two rainy or cloudy days, a backup diesel genset is the cheaper alternative to a widely oversized PV system plus huge battery .”

SMA has delivered solar-diesel hybrids to customers in South America, the Caribbean islands, various African countries, India and the South East Pacific region.

“In all of these regions, diesel is one of the dominating energy sources, and the costs for supplying fuel on-site are a significant share of the overall economics ,” said Wachenfeld.

This situation means that replacing even part of annual diesel consumption with solar power can yield significant savings.

“Today, taking the current diesel price situation into consideration, we see diesel electricity generation costs of approximately USD$0.20 to $0.35 per kWh, whereas PV can guarantee generation costs of between $0.06 and $0.10 ,” Wachenfeld noted.

“The gap is significant, and this gap is driving the urge to substitute fuel-consuming diesel gensets with PV. Diesel power supply is expensive in terms of operational expenditures, and PV has proven that even the most challenging cost targets have been met .”

Enerwhere, a Dubai-based company that specialises in providing solar-diesel hybrids on a rental basis, claims its systems work out 20 to 30% cheaper than using diesel gensets alone. And the savings are not just in fuel costs, but also in diesel plant.

Daniel Zywietz , founder and CEO, tells of a labour camp that that Enerwhere has equipped with 11 generators for a 1.5 MW peak load in winter. “When you have a megawatt of PV running, instead of running nine generators you would only run six or seven ,” he said.

“You save diesel fuel, you save run hours of your generators, and if you are confident about your weather forecast you could even reduce the number of generators in the summer or move them to a different area where you have no PV .”

Another advantage of Enerwhere’s rental model is that it allows cost-effective power to be provided on a temporary basis at locations such as building sites. “Most off-grid clients are not off-grid forever,” Zywietz said.

“In the construction business or the mining business you are talking about project lifetimes between one and seven years. The feed-in-tariff people are used to signing 20-year contracts but we have not found anybody in the developing market willing or able to sign a 20-year contract .” 

Thanks to these benefits, SMA’s Wachenfeld believes there are strong prospects for growth in PV and diesel system sales, particularly in sunbelt countries with high fuel prices.

“As PV costs still decrease, steadily but no longer rapidly, we see a sustainable market development ,” he said. “At the moment, financing is one of the barriers that has to be overcome, but the message is plain and clear: hybridizing means saving money. ”

On 2-3 March 2016 , the second edition of the “Solar/Diesel Africa ” conference will take place in  Johannesburg, South Africa. Learn more about the previous edition in 2015 and sign up for updates on the upcoming conference on www.solardieselafrica.com .