How do you calculate the availability of your solar power plant (SPP)?

Availability is one of the most important performance indicators, and it directly shows the quality of operation and maintenance services for the power plant. So how should this calculation be done?

In SPP, energy production takes place in solar panels and comes to the inverters from there via transformers. Apart from the malfunctions experienced throughout the plant, distortions can also be experienced in particular panels. For these reasons, while calculating the availability of the SPP, all the distortions and malfunctions experienced should be taken into account and calculations should be made in accordance with the availability conditions.

Unlike the capacity factor, the availability calculation should be made over time, not energy generated. The order of availability is simply the ratio of the actual working time of the SPP and the time that the SPP can operate.

To formulate,

• GÇZ = Total running time of SPP (hours)
• ÇZ = Total time that SPP can work (hours)
• GAZ = Total failure time of SPP (hour)

When calculating the actual running time of SPP, it is necessary to determine the time weight of each module of SPP and the data that can be received in each string. This weight is calculated by proportioning the maximum energy that the module can produce in standard test conditions (STC) and the maximum energy that SPP can produce in STC. Solarify automatically calculates the time weights of the modules (Solar panel, Solar arrays and inverters) according to brand and model information.

After calculating the time weights, it is determined whether the modules are operating in the time interval for which the availability is examined. At this point, unlike performance ratio and capacity factor, the performance of the module is not taken into consideration. SPP is found to work by realizing the downtime of the modules and multiplying by the time weights.

• ZA = Time weight, coefficient calculated separately for each module
• MAZ = Module downtime, unit time of the module (hours)
• MS = Number of modules
• GAZ = Total failure time of SPP (hour)

In order to calculate when SPP can operate, radiation sensor data are examined. SPP is expected to be able to operate at all times when it receives radiation above certain values. These specific values can be determined by users of the Solarify monitoring system.

• BIS = Specific radiation limits (w/m2)
• IZ = Actual radiation time (hours)
• ID = Radiation value (w/m2)

After collecting the necessary data, the availability calculation is made by following the formula below, these data can be easily observed for the desired time intervals in the Solarify monitoring system.

Grid Outages

Occasionally, there are interruptions in SPP that are not caused by power plants. Some interruptions, such as interruptions from the distribution network, should not be reflected in the actual availability account.

Solarify smart reporting system calculates availability based on the information received from the alarms created in the Solarify monitoring system, taking into account such interruptions. Since there is no production in non-ges cuts, only the denominator formula is changed.

DKZ = External downtime (hours)