National Grid’s Renewable Energy Growth program contracted with the Cadmus Group to inspect 100 solar power systems installed in the state. The powerpoint version of the report, Study of Renewable Energy Installation Quality in Rhode Island (the official presentation can be found here – pdf), looked at 100 installations in the state in November of 2018. The group found that 45% of the 86 residential, 8 medium sized and 6 large sized projects – built by 27 companies – inspected exhibited major or critical installation deficiencies.
The program’s scoring metric is as follows:
Looking at the residential projects, the issues by inspection element were:
- AC Combiner – 31
- AC Disconnect – 5
- Array – 190
- Inverter – 81
- Junction Box- 6
- Optimizer – 4
- Overall Observations – 3
- Production Meter – 2
- Supply-Side Connection – 187
- Total – 509
Cadmus noted that more than 70% of installation companies responded to reports of their system installation issues, however, only 33% of those reports resulted in actual corrective actions.
In the small-scale systems, there were 25 examples of racking mechanical connection issues, such as connections incorrectly made or variations from the installation instructions. The below image shows a missing rail support, that could lead to premature system failure as the aluminum could bend over time, shifting the solar modules connection to the racking system.
Improperly secured solar modules were noted in 28 instances in small scale installations, with missing, incompatible, or inappropriately-installed hardware. Missing clamps, bent bolts (see header image) due to incorrect cuts to the length of rails, and incorrect hardware used in tying down modules. While most of these issues weren’t considered critical – over the long time – they can lead to hardware not staying in place.
Conductor – wiring – issues were also observed, and comprised most issues noted with medium and large scale system. For instance, below a rooftop solar installation’s rapid shutdown requirements aren’t properly met as the hardware to manage this shutdown process was located more than ten feet from the solar modules to be shut down in the event of an incident.
Other conductor issues included, unprotected or improperly-supported conductors. These issues lead to wires lain atop metals (below image)that can cut through the outer sheath over time, or unsupported wires that can sit in water if it pools on the roof.
Two instances of DC connectors not properly connected or used outside of the product listing were found (and this is actually one of the main issues that were found in the Tesla-Walmart fires). Cadmus notes that hazards exist when DC connectors are not properly installed, these connections can cause heat, arcing, poor electricity generation efficiency or a thermal event (fire).
Rhode Island also inspected the interconnection techniques – and Cadmus actually found that there were four systems installed (3 residential and one commercial installation) – in which the solar power system wasn’t actually hooked up to an electrical meter that was measuring the production. Obviously an issues.
There were also 23 noted wire splice issues, such as methods not rated for the specific environment or conductor type, which over time would lead to risk of premature failure due to environmental conditions. For example, the below connectors not suitable for exposed outdoor locations.
In general though, most customers – 86% – were still very happy with their installations, with 12% having a negative perception of things. And even though most customers were happy, 26% of respondents said payments generated by their system were lower than expected. Some of them were not properly informed of the tax implications of cash payments generated by the system, that monthly payments are dependent on actual energy produced, and weren’t fully communicated the delays between when the system started producing energy and when credits appeared on the utility bill.
Editor’s note: Are you interested in learning more about solar installation techniques, and how to avoid fires at solar plants? Be sure to attend pv magazine’s Quality Roundtable at the Solar Power International trade show in Salt Lake City on September 25, from 2 PM to 4:30 PM. Space will be limited, so click here to learn more and to register.