Rationales for Photovoltaic Hybrid Power Plants

Renewable power has significant potential to reduce the cost of electricity in rural and island settings and in areas distant from main power grids or reliable sources of power. Currently, many industrial consumers in underserved power regions of the world with weak or no grid infrastructure ensure their power supply using diesel fuel. Because the power supply from the grid is unreliable, diesel generating sets are usually running constantly to ensure maximum reliability and availability for energy intensive industries, such as agriculture, water desalination and mining. But, diesel fuel is expensive, both to purchase and to transport, which leads to unsustainable costs for the industrial consumer.

A photovoltaic diesel hybrid power plant without storage

Industrial consumers in remote or underserved regions seek cost efficient energy solutions in order to remain competitive, but any solution must be relatively inexpensive, ensure stability of supply, and be scalable. Until recently, electricity generated by solar photovoltaic technology has been expensive, limiting feasible deployment in such regions.

But, the latest report from GlobalData in January of this year indicates that the price of solar power system installations has decreased significantly in recent years and is forecasted to continue to decrease:

“The crystalline silicon (c-Si) and thin-film modules have seen large price drops since 2010. The average price of a module was approximately $2.17 per watt and $1.99 per watt in 2010 for c-Si and thin-film modules, respectively…This price is expected to fall further during the forecast period, reaching $0.48 per watt and $0.46 per watt for c-Si and thin-film module, respectively, by 2020.”

As photovoltaic system prices continue to drop, there is a fantastic opportunity for photovoltaic hybrid systems to become the power source of choice in these remote or underserved regions. First and foremost, many of these industrial regions are plentiful in solar irradiation. Secondly, photovoltaic hybrid systems can be integrated into the existing diesel generator set infrastructure without any considerable difficulty. Third, the stability of the power supply is guaranteed: during peak irradiation periods, the photovoltaic system may be sufficient, and the generator set is always available in case of shortage. Furthermore, if an energy storage unit is added to the configuration, the savings on fuel and CO2 emissions can be even more significant.

A large photovoltaic diesel hybrid power plant with battery storage system commissioned in the Bolivian Department of Pando in December 2014. The combination of 5.2 MW PV output and 2.2 MW battery storage system with 152 MVA installed generator set capacity provides 55,000 residents with electricity.

Since 2008, heterojunction technology has been studied and manufactured by Meyer Burger, a Swiss technology company. Heterojunction technology combines the advantages of crystalline silicon (c-Si) solar cells with the thin-film module technology, to produce heterojunction cells that have efficiency rates of more than 22% and lower temperature coefficients than regular solar cells. The increased efficiency of the heterojunction cells, coupled with the ease of production which makes them inexpensive, indicates that photovoltaic systems could become an even more persuasive solution for industrial consumers looking to implement hybrid photovoltaic systems in remote and underserved regions.

A rendering of a solar cell, based on heterojunction technology

However, there are significant obstacles to widespread implementation of hybrid photovoltaic systems in these regions. Many of the industrial companies who might seem to be ideal candidates for early adoption lack the capital to finance such a shift to hybrid solutions. Furthermore, there is a strong market for rental diesel generator sets. In addition, in many of the candidate industries (especially mining), the operating time is too limited, and the lack of mobility of solar power plants renders them less desirable.

Over the next few weeks, I will continue to explore hybrid photovoltaic technologies, financial considerations, and implementation obstacles in order to better understand whether these hybrid systems are likely to be compelling investments for industrial consumers. I will also try to determine whether the environmental benefits of switching to hybrid photovoltaic systems are significant or relatively insignificant. I’ll also try to assess whether heterojunction photovoltaic technology could have a disruptive effect on the economic considerations in the near future.