April 18, 2022

Significance of Storm Drainage system on Solar PV

by wpweb_sgurrenergy in Blog

Tariff for the Solar PV plant is gradually decreasing globally. Therefore, cutoff in the expenditure on project components which does not directly contribute in revenue generation becomes very essential. Environmental and natural calamities may significantly impact the power generation and operating revenue loss. Non-revenue generating components may secure the loss of generation due to environment and natural calamities. Below sections presents one of such non-revenue generating component ‘Storm Drains’.

Before planning the storm drain, it is necessary to understand whether it is really required. If the absence of appropriate and adequate drainage system can directly or indirectly impact the power generation and leading to operating revenue loss, then need to understand, the significance of the impact, how often the flood risk may occur, is there remedial measures other than providing drainage system mitigating or minimizing the flood risk, is the drainage system feasible and if feasible, can we reduce the system cost.

Direct Impact

Absence of drainage system may lead to flooding/water logging as shown in Figure in the Solar PV plant entirely or locally due to which PV modules, cable joints, cable trench in control room, inverter station, string combiner box etc. may submerged in water and may lead to generation loss and ultimately the direct revenue loss. Any damage to the inverter station may significantly impact the maintenance cost. Repair or maintenance of inverter may take several days which may lead the generation loss for long duration.

Water Logging / Flooding in Solar PV

Ground clearance to the PV module can be increased to avoid the module submergence, however, it may lead to increase in post height in the entire plant. Bed level of cable trench in control room, plinth level of inverter station may be maintained adequately above the ground level/flood level by increasing the plinth height which may not increase the cost of construction significantly. Suspended cable with joints may be supported appropriately above the high flood level to avoid any short circuit and loss in generation. It is also necessary to understand the inundation time, as it will directly influence the power generation.

Indirect Impact

Water logging or flooding may impact on foundations, roads, buried cable in trenches, boundary walls etc. which may lead to indirect operating revenue loss. Submerged foundations may get settled which may result the stresses in mounting structure passing on PV modules. It may impact on PV module performance, its generation capacity and ultimately may lead to revenue loss. Foundations may be designed for submerged condition; however, it may lead to increase in cost of foundation. Foundation on hard and non-cohesive soil may have less impact in submersible condition. Flooding may erode the non-cohesive soil if the ground has steep slopes. Foundations may get exposed due to soil erosion. Provision of drainage system may avoid the risk of soil erosion around the foundation. Instead of providing drains, provision of bunds may minimize the risk of soil erosion, however bunds may lead to waterlogging on upstream side of the bund. In-undated area due to the water logging may not be significant, if the land has steep gradient and if the ground has no steep gradient, there may less probability of soil erosion.

Road in submerged condition may lead to undulations and cracks in the road surface. It may increase the cost of maintenance and all time accessibility at any location. In submerged condition, boundary wall foundation may get settled. Water logging on one side of the boundary wall may lead excess pressure on the wall. Failure in boundary wall may lead to increase in cost of maintenance and there may increase in risk of theft. Thus the waterlogging/flooding may impact the various components of the Solar PV plant with varying significance and their remedial measures may vary in cost.