Study: High-risk through water use in solar sector

Market intelligence and consulting firm, Bridge to India has released a new report laying out the effects of solar PV deployment across India on regional water management. While the technology is often lauded for requiring little water compared to thermal energy generation (0.1 m³/MW against 2.2m³/ MW), Bridge to India says the former’s impact is exacerbated by the fact that solar plants are predominantly built in arid and remote regions.

In addition to the fact solar gravitates towards arid regions, as they promise higher irradiation levels, the market intelligence provider also found that India’s solar installations appear somewhat concentrated. As such, five states comprise 70% of the country’s installations, it says. For example, Karnataka accounts for 23% of solar installations, Telangana for 14% and Rajasthan for 12%, demonstrating the strong clustering of installations in these regions.

As water availability between, for example, Karnataka and Rajasthan varies greatly, so does the way solar O&M contractors handle water in these regions. While in Karnataka water is used more generously for module cleaning, contractors in Rajasthan are thriftier. Speaking with a range of O&M contractors from these regions, Bridge to India revealed that water use levels per module per cycle range between slightly above one liter, and can go as high as four liters.
According to the report, soiling effects can reduce a plant’s performance by as much as 3-6%, putting at risk the site’s economic viability. To reduce the effects to just 1% of operating assumptions, around two cleaning cycles per month are necessary to remove dust, dirt and bird droppings.

Resulting from this estimation, in conjunction with the installed capacity and knowledge of water availability in different states, the authors have mapped the state of water scarcity incurred by solar PV across India.

It estimates that 94% of India’s solar capacity is exposed to medium to high level water risk. Rajasthan, for example, is estimated to require 600,000 m³/year for module cleaning. The state is highly arid, and this water use reportedly further exacerbates the situation.

While Karnataka is located in a considerably more humid region than Rajasthan, the higher installation capacity here also requires more water use for cleaning. The 1,000,000 m³/year for module cleaning still places the state at medium to high risk, according to the scale established by Bridge to India.

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