Solar PV plants can be classified in three simple categories, with regards to their performance:
- Good or adequately performing solar plants (according to base-case scenarios)
- Apparently good operating solar PV plants
- Clearly distressed assets with evident underperformance issues
“Apparently good operating plants” is related to low quality of information due to unreliable monitoring systems or limited reporting transparency from the O&M contractor, or both. Several solar systems in this category can easily slip into “underperforming” when key performance indicators (KPIs) like performance ratio (PR) or availability (AVA) measurements are not precise and coherent.
Whereas PR and AVA are KPIs that are meant to measure the performance of an O&M contractor, banks and investors find it more useful to benchmark their assets with KPIs related to their base-case scenarios, such as solar index, and make comparisons between actual and base-case values. While this is a useful tool for evaluating the financial performance of an asset, it is less useful for technically evaluating a plant. In periods with high irradiations, actual performance may exceed the base-case scenario even in a technically underperforming plant. Similarly, during periods with lower than expected irradiations, the plant may be performing below expectations, but it could be a very well performing plant.
A lot is being said about improvement of PV plants, especially in Europe, where there are many underperformance issues. This is mainly due to the following reasons:
- Plants were constructed under extreme time pressure.
- EPCs had limited or no experience in solar PV.
- EPCs who undertook the O&M of the plants in the first years stepped in to financial difficulties and neglected their activities and obligations.
- O&M has been very often perceived as a cost burden and the real benefit was not fully realized.
Worldwide, we can learn from EU hindsight and counter shortcomings in advance. Choosing a knowledgeable and professional O&M contractor may prove to be a great asset in these cases, where the contractor acts in the first phases as a technical consultant by examining the technical details of a PV plant and proposing to the system owner a specific action plan to restore performance levels. In this respect, the O&M contractor’s interest is very much aligned to the interest of the plant owner.
Many monitoring systems are offered in the market, and investors find it difficult to make the best choice. Many people focus a lot on an attractive user interface, which is what first impresses possible buyers. Only rarely is the technical background explained and even more rarely do non-technical people have the capacity to understand the technical challenges of such a monitoring system.
Choosing a monitoring system that is not technically sound will deliver imprecise measurements with gaps in measured data. KPIs calculated on such data will also be imprecise. In case the deviations are on the positive side, the calculated KPIs will appear better than reality, and false judgments will be the consequence. The situation may get even worse if the O&M contractor does not report in a transparent and detailed manner. This is the category which we call “apparently good performing plants.”
“Apparently good performing plants” are therefore more complex to troubleshoot. Fortunately, such issues become evident as soon as a new, better monitoring systems are used. The more detailed the monitoring system, the easier it becomes to discover the deficiencies of the previous one and reveal sources of underperformance.
Now is the time to save yourself from becoming an “apparently good performing plant” that slips to “underperforming” (the EU experience). Please write to SolarPro for a discussion.
This article was contributed by SolarPro