The solar industry has been experiencing large scale growth globally over the past few years in relation to solar hardware costs which are going down. The growing number of online projects and projects coming through the pipeline are creating an ever-growing demand for Operations and Maintenance (O&M). As the industry matures the demand for reliable and efficient O&M increases and is driving the O&M industry to adopt standardized initiatives.
Tracking Key Performance Indicators (KPI) helps to communicate to your team what the criteria for success is as well as getting everyone focused on a set goal. KPIs provide a means to track and compare the PV Plant’s performance so careful planning is required in the selection and development of your company’s KPI. There isn’t a set of KPIs that every solar operator uses; however, we’ve gathered a list of the top 10 O&M KPIs to track.
1) PR – Performance ratio
This ratio is the relationship between actual plant energy production and designed target energy production while taking environmental factors and energy loss into account. The energy loss is through conductive thermal loss and operational energy consumption from the panels to the grid. This enables investors and operators to compare different plants based purely on the performance factor of the plant and on an even scale.
2) PA – Plant availability
The PA is calculated as a percentage to represent the time that the power plant is available to provide energy to the grid. This can be thought of as the up-time of the plant. Solar PV plants usually have little downtime resulting in a higher percentage of availability. The plant availability factor should not be confused with the capacity factor.
3) MTTR – Mean time to repair
This metric measures the maintainability of the solar PV plant and its components. This is the average time it takes for repair to be completed. To calculate this, you record the total time for corrective maintenance divided by total number of tickets for repair. For example, if issue 1 took 10 minutes for repair and issue 2 took 2 minutes to repair, the MTTR is 6 minutes.
4) MTBF – Mean time between failures
This metric represents the reliability of the power plant. This is the mean time between system failures. Although for electronic devices the MTBF is counted in hours the MTBF for solar modules and components are typically measured in years. The MTBF is useful to measure over a long period of time and it represents the likelihood of failure and should not be used as a prediction to when the parts will fail.
5) DCC – DC Capacity – Direct Current
The capacity is usually referring to the maximum energy generation in direct current and measured in watts.
6) ACC – AC Capacity- Alternating Current
This capacity will be lower than the DC capacity as there is loss in energy when converting DC to AC. Although it is useful to see the DCC and ACC by themselves, when you view both metrics together an operator can see the loss of energy due to possible clipping or energy loss from converting current through the inverter.
7) PI – Peak Irradiance
Solar irradiance is the energy that’s emitted from the Sun to Earth. This is calculated by measuring the solar energy in watt per unit area, commonly a square meter (W/m2). The peak irradiance is the maximum measured solar irradiance.
8) TT – Ticket Types %
Tickets are generated from a variety of issues from different sources. Tickets vary greatly, but not limited to, inverters overheating to vegetation abatement to compliance checks. Tracking the Ticket Types as a percentage assists with identifying and maintaining control over issues by comparison from each period.
9) V – Variance between expected kWh and actual kWh
Forecasting energy generation as accurately as possible is essential for plant operations. Although there will always be variances between the expected kWh vs the actual kWh, monitoring the variance over a period of time could shine light on incorrect data or lead to other problems such as weather or hardware.
10) PSH – Peak Solar Hours
The PSH should not be confused with total daylight hours. The difference between daylight hours and PSH is that PSH is defined in hours the duration of sunlight that exceeds 1 kW / m2.
Although annual or quarterly targets are communicated to the O&M team, it is often difficult for team members to scale these targets into daily or hourly goals. KPIs provides that missing link where everyone on the team can gauge their efforts towards the target. When looking at performance measurements on a granular level, it allows for the company to measure the maintainers performance on a daily basis as well as increase the reactiveness and proactiveness towards the success of a high performing PV plant.