Suppose we have a photovoltaic plant of about 1 MWp, with an expected production of 1,350 kwh/kwp per year and a revenue from incentives and sale of energy equal to 0.35 € / kwh. We consider a standard maintenance activity that includes weekly checks of inverters and parallel panels and monthly inspection and measurement of productivity of each individual string.
We evaluate the incidence of production losses (and revenues) due to malfunctions and failures of strings and modules:
1. Failure to produce a string
Possible causes: broken modules, open or blown connectors, broken or damaged cables, blown fuses, landslides of the ground with moving structures
Annual fault estimate: 5%, equivalent to 18.25 events per year
2. Reduced production of various plant strings
Possible causes: modules with hot spots, broken glass, water or moisture infiltration, localised dirt, unplanned shading.
Estimated annual loss compared to optimal production: 3%.
The table shows the estimate of the loss of revenue due to these two common types of malfunctions and failures, in the case in which we rely exclusively on the standard maintenance service and in the case in which this service is integrated through the WiEgg system.
Using the WiEgg system, the non-production of a string is detected instantly and therefore the negative impact on production can be minimized. On the other hand, the problems that can cause the reduced or in any case not optimal production of a significant number of strings, are difficult to detect even if proceeding to frequent measurements in the field.
The WiEgg system provides a classification of the performance of the strings evaluated over a period of time at the discretion of the user: in this way the maintenance technician can intervene, in a guided way, primarily on the strings that have recorded the worst performance compared to those that, at the same irradiation, were the best. In this way, it will be possible to significantly reduce the losses from reduced production.
In the case in question, even if we adopt very prudent hypotheses on the reduction of these losses thanks to the WiEgg system, we calculate a recovery of revenues of about 13,000 euros per year.
Moreover it is possible to estimate a further increase of the total profitability due to the reduction of the cost necessary to guarantee the contractual maintenance commitments because, thanks to the WiEgg system, the inspection and the measurement of the manual productivity of every single string will no longer be necessary.