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Solar Panel Maintenance & Performance
Tuesday, September 22, 2020
MAINTENANCE AND MONITORING
All things require maintenance whether it’s a backyard garden, the car you drive to work, the public transportation you use or the machinery used in factory automation. A commercial solar system is no exception. In addition, a monitoring program is also highly recommended.
CLEAN ENERGY ACCREDITED DESIGNERS AND INSTALLERS
Solar systems installed by CEC accredited companies should include a maintenance schedule as part of the agreement but if this is offered it usually only applies for a short period of time.
As part of the requirements under Australian standards an installer/designer of a solar system must include documentation that specifically states:
- Recommended maintenance for the system
- Maintenance procedure and timetable
DOCUMENTATION IS NOT ENOUGH
Documentation showing what maintenance should be undertaken and a timetable must be provided but the actual maintenance doesn’t! It is a recommendation rather than a mandate.
As a result of the old should/shall adherence to standards many companies only offer maintenance as an option or to “close the deal” when in fact it should be part of an ongoing service agreement that maintains the installed system in tip top condition, maximising output and thereby maintaining ongoing reductions in money spent on electricity.
WHAT IS ACTUALLY MAINTAINED?
The maintenance recommended in the Australian Standard AS/NZ 5033 can be classified into three separate but connected categories:
- General Cleaning (covered in our Solar Panel Cleaning Blog)
- Electrical safety, wiring integrity and measurement
- Structural integrity of the framing and cable support system
ELECTRICAL SAFETY, WIRING CHECKS ETC
This area of maintenance can be subdivided into the following:
- General visual inspection
- Physical integrity checks
- Component tests
GENERAL VISUAL INSPECTION
The visual inspection methodically goes over the whole system and checks for the integrity of cable entrance glands, fractures on panels, moisture penetration, noticeable damage to conduit, status of cable tray (dented, loose lid etc), rust, frame corrosion, bolts and screw corrosion and inverter damage.
The visual inspection can quickly identify potential issues that may need to be rectified.
PHYSICAL INTEGRITY CHECK
The next level is the physical integrity check where the installer tests the cabling conduit, junction boxes, tightness of electrical connections, integrity of clamping devices, lid seals, water accumulation and build up.
In addition there are checks to see if all labelling is intact, not peeling and clear to read. There is also a check to see whether existing shutdown procedure documentation is up to scratch and easily found when required.This process may also involve, if applicable, replacement of components that have suffered or have been damaged, conduit from pests and wildlife, see below:
This is where a licenced electrician is required as it involves work such as:
- Verifying blocking diode operation
- Checking surge arrester degradation
- Measuring open circuit voltages and a host of other tests
Obviously the ongoing electrical safety of any system is of the utmost importance.
STRUCTURAL INTEGRITY TESTS CHECKS
This part of the maintenance schedule involves checking the structural integrity of:
- The framing system
- The cable tray/conduit system
- Panel mounting (roof or ground mount)
As solar panels are mounted outside and therefore subject to potentially extreme conditions, regular inspections are necessary to check structural integrity.
FULL SYSTEM AUDIT
Sometimes a full system audit that abides by current applicable Australian standards may be required.
This full system audit is offered to customers in the following situations:
- As part of complete maintenance service to businesses with commercial solar
- Businesses involved in warranty disputes with other installation companies
- As a requirement of insurance stipulations
Monitoring means periodically checking the output and consumption status of a commercial site with or without solar installed. This is achieved by installing certain equipment on-site that measures energy flow, in and out.
For example, we have a 500 kW solar system that goes down in December for a week - let's say in Melbourne during a particularly sunny period.
Daily output per kW of panels installed is about 2850 kWh/day. Multiply this by 7 x days and the total energy lost is 19,950 kWh.
Now let’s assume a 50:50 split between production used on site @ $0.25/kWh and exported @ $0.09/kWh:
- Dollar value lost on loads (electrical site loads) = $2493
- Dollar value lost to grid (energy unused on site and exported to the grid) = $897
So total lost over this period is $3390
The importance of monitoring is not only a checking process for potential issues but also an insurance against production losses.
Certain monitoring products not only monitor production, but they monitor site consumption. By carefully analysing daily peaks, certain energy management strategies can be suggested to improve overall energy usage.
For example, a nursery experienced peak loads (irrigation pumps coming on via timer) at 10am that are only partially serviced by the solar. But if the loads were delayed by, say 30 minutes, it could be serviced by almost 100 % of the solar energy leading to even more electricity savings by more efficient utilisation of solar on the site.
SOME INTERESTING DATA EXTRACTED
Extrapolations can be made from the size of the system that has been installed compared to the consumption/production profile for different periods of the year; monthly, weekly, daily, even hourly.
For example, using the nursery again, December 18 produced 556 kWh from the solar system but consumed a total of 1213 kWh.
This a production:consumption ratio of 0.458:1. This means that nursery’s consumption from solar as a % of total consumption is 45.8 % roughly.
So for each site we can look at the following relationships on a daily, weekly, monthly basis:
- Solar production to overall site consumption
- Solar production to solar produced site consumption
- Solar produced site consumption to solar production exported
- Energy from grid consumed on-site to solar production exported
DATA ANALYSIS LEADING TO ENERGY MANAGEMENT STRATEGIES
All of this data can be converted into ratios and the results can be used to determine and suggest certain energy management strategies that will further reduce reliance on the grid and bring overall energy costs down.
Maintenance of any system is of the utmost importance and this thinking also applies to commercial solar systems. Making sure that the components are all intact, connections are firm and the overall structural integrity is maintained is crucial. Even a simple visual check can uncover potential issues that can have ramifications for overall system safety and output.
The other side of the coin is monitoring. This is where the systems ongoing “health” can be observed and analysed. It’s from this information that additional energy management strategies can be suggested to further reduce grid reliance and more effectively utilise the solar produced on site.