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Study: High-risk through water use in solar sector


Study: High-risk through water use in solar sector

Though lauded at times as a water-saving technology, PV’s concentration in arid and remote regions, in conjunction with inefficient cleaning methods, can exacerbate water scarcity and prompts rising water tariffs for plant operators, according to a new report on Indian PV installations, published by analysts Bridge to India.

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 solar PV is lauded as a technology that generally requires 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 prevailingly built in arid and remote regions.

On top of the fact that 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, the five states with the highest installations account for 70%, according to Bridge to India’s information. 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 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 sites 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. Intelligence firms estimate that 94% of India’s solar capacity is exposed to medium-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-high risk, according to the scale established by Bridge to India.

Water scarcity in these regions has led to massive price hikes over the last years. In Rajasthan prices for water have doubled over the last 3-4 years, due to rising demand. In Karnataka, the water tariff for industrial use multiplied 100 times in 2018. Currently, the solar industry uses about 4,000,000 m³/year for the existing 25 GW of installed solar capacity. However, India is on the path to drastically increase installations at a rate of about 10 GW per year. Bridge to India calculates that by the time the country has installed 65 GW, water consumption will have risen to 12,000,000 m³/year, which would further aggravate the problem. Though solar PV is not the sole culprit here, the adverse effects for the industry are significant, as cleaning accounts for 26-35% of total O&M costs.

Resulting from this analysis, the authors elevate water mitigating cleaning solutions, such as robotic cleaning and anti-soiling coating to an imperative position. Reportedly, in India, around 3 GW of installations are eyeing various types of robotic cleaning, which is said to reduce water need by 50-100%. By Bridge to India’s estimations, robot cleaning solutions would add around $0.016/W, which translates into a CAPEX increase of 3%. Though, this would be offset by virtue of a more stringent cleaning regime, resulting in 1-2% generation gains per year. The gain in conjunction with the reduced water use would result in amortization of the extra CAPEX in 2-3 years.

Furthermore, anti-soiling coating would pose a viable solution to the issue, according to the authors. While previously, ‘after-market’ solutions have not received much popularity over concerns of assumed efficiency losses, and durability of the coating. Nowadays integrated solutions with a lifetime warranty are catching some attention. Module costs would increase by around $0.005/W, and water consumption could be reduced by up to 35-50%. The authors highlight that there could be 1-2% increase of incremental power output depending on the location.

Source PV Magazine

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