If you’re home owner that’s had solar panels installed for some time you may be wondering – do they need maintenance? You may have even been contacted by a company trying to sell you a maintenance package. If you have a commercial roof your insurance company may have introduced a solar panel maintenance clause. What’s the truth behind these maintenance requirements?
We’ll look at domestic roof top solar separately from commercial roofs, starting with domestic rooftops.
Domestic Solar PV installations
If you’ve had your solar panels installed on your home for some time you may wonder if they need maintenance. You may also have received emails, phone calls, or even someone knocking on the door claiming that your panels need to be maintained. But what’s the truth behind these claims?
Microgeneration Certification System (MCS) Solar PV Standard
Version 5 of the MCS standard incorporates change from the IET code of practice issue 2 and includes an advisory section on solar panel maintenance.
MIS-3002_Solar-PV-Systems-V5.0-Final-for-publication.pdf
Whilst MCS standards are not mandatory, they are the most widely recognised Solar certification body. The standard closely aligns with the Institute of Engineering and Technology (IET) Code of practice for grid connected Solar Photovoltaic systems . The IET publish BS7671 IET Wiring regulation that form Part P of the building regulations.
So we should take note of what the MCS Solar standard says regarding solar PV maintenance.
Section 7 of the standard says the following regarding maintenance:-
7.3 A maintenance schedule including the checks to be undertaken and their frequency is given in Appendix F according to building type/occupancy.
The maintenance checks suggested along with their frequency are advisory only and include:
• Customer checks (visual only)
• An intermediate maintenance visit by an MCS Contractor
• A full maintenance visit with more involved tests requiring specialist equipment,
again by an MCS Contractor.
It should be noted that currently the maintenance checks are advisory only.
So what does Appendix F say?
Appendix F Maintenance Schedule MCS Solar Standard Issue 5
An extract of MCS standard issue 5 appendix F.
So we can see that for rooftop solar PV installations that are 10 years old and 15 years old checks by an MCS contractor are advised, but not mandatory.
Annual checks can be undertaken by the customer.
This changes for rented properties, public buildings, and commercial properties.
Does my insurance company require these checks?
You will obviously need to check with your own home insurance company, but we are not aware of any domestic insurers requiring Solar PV maintenance or checks.
The same is not the case for Commercial insurance.
Commercial Rooftop systems Solar PV maintenance
We’ve recently come across some commercial insurance companies requiring regular Solar PV maintenance checks. In particular AXA and Aviva have introduced these requirements. Though solar panel fires are rare, this seems to be related to some recent high profile rooftop solar fires on commercial buildings resulting in claims.
However not all insurance companies have gone this route. For example the NFU do not have this clause in their commercial property, and simply require you to declare the value of the installation.
Though we cannot advise you on insurance, at least on a cost comparison basis, for a small business it may cost less to switch to an insurer without the maintenance requirement than it does to employ an MCS contractor to carry out checks – particularly if they need to put up scaffolding and carry out on roof checks.
How likely are rooftop solar panel fires and what are the causes?
The UK government carried out research into the causes of solar panel fires which you can read here… Fire incidents involving solar panels – GOV.UK
The report investigated 80 occurrences of solar PV fires.
They noted that the occurrences of PV fires tended to be in the first sunny days of spring.
The table below is taken from the report and notes the components at fault.
Reason for failure
The most likely cause in the majority of cases is poor installation.
In the case of the DC isolators the causes were further identified as incorrectly specified products using underrated DC isolators, or isolators intended for an AC system.
They also identified cable runs entering the top of the isolator leading to water ingress. This is an error that a correctly trained apprentice would be aware of and would generally avoid. It’s always better to loop cables into the bottom of isolators such that the water drips off the cable onto the floor, and doesn’t track down the cable into the isolator.
The second most common cause of failure was the DC connectors or MC4 connectors used to string together panels.
In a few cases inverters were identified as the cause of fire.
Approximately 36% of incidents recorded that were caused by PV systems were attributed to poor installation practices. 5% were attributed to faulty products and 10% to system design errors. The causes of the remainder were unknown.
A similar analysis of international data came to similar conclusions:-
Where PV systems have been the cause of fires, some themes emerge. Much attention is paid to the phenomenon of electrical arcing, where a current flows across an air gap by ionising the air. High voltage arcs are extremely hot and can cause combustion of surrounding materials in less than a second. Arcing can occur where conducting parts become physically separated by mechanical
movement or mis-alignment. Also, a build-up of contaminants (e.g. oxide) on electrical contacts can cause resistive heating, resulting in the breakdown of materials and subsequent arcing.
Certain components, if incorrectly specified, poorly installed or contain manufacturing faults, are typical locations of electrical arcs:
• DC connectors
• DC isolators
• Inverters
• PV modules, including by-pass diodes and junction boxes
At the time of this report there were 940,000 solar PV installations in the UK of which the 80 noted fire incidents represent 0.01%. So the likelihood of a solar PV system fire is very, very low.
Would periodic maintenance checks have picked up some of these faults? Perhaps. The scheduled list of tests does correlate with the identified causes of failure in the report.
Avoiding scams
When changes are introduced there is always the possibility of someone trying to exploit it. MSC issued this recent scam alert bulletin where cold callers were telling people that their solar warranty has expired and that people should take out a maintenance package…
MCS issues solar scam warning – MCS Certified
Cleaning Solar panels
Solar panels can accumulate dust and dirt over time and so it will improve their performance to gently clean them every eighteen months or so.
Turn off your solar system before cleaning – check the manual if you’re unsure how to do this. It’s also a good time to visually check for cable damage. Don’t proceed if you see a damaged cable and seek expert help. Zero Chippenham can help with this.
The surface of a solar panel is glass and can be cleaned with a long soft brush, a gentle wipe and biodegradeable soap. Avoid washing up liquid as this may leave a film on the panels. Don’t stand on the panels and don’t use a jet wash as this might get water into electrical seals.
You can use a soft spray from a garden hose on top of the panels if you can’t reach them or ask your window cleaner. Some may be willing or experienced with some guidance.
Conclusions
There is no mandatory requirement to undertake solar panel maintenance. There is however an advisory requirement that varies in frequency of checks depending on the type of installation.
Solar panel fires are very, very rare – 0.01% of all installations. Even then they vary in severity. Where fires do occurs the majority are due to poor installation practices or incorrectly specified equipment.
The Zero Chippenham Community Solar scheme uses a trusted and experienced local installer.
The advisory checks in the MCS document appear to be designed to some extent to identify the potential causes of solar panel fires.
Commercial business insurance companies such as Aviva and Axa have recently introduced clauses for solar PV maintenance checks into their commercial insurance policies. Though this is by no means universal, for example NFU haven’t introduced such a clause.