RC62: Recommendations for fire safety with PV panel installations, has now been published.

We are pleased to announce the RC62: Recommendations for fire safety with PV panel installations, The Joint Code of Practice for fire safety with photovoltaic panel installations, with focus on commercial rooftop mounted systems ,has now been published. Helios’ Director Robert Harley has lead the process, with document written by James Hoare CEng FIET FEI, arguably one of the UK’s most senior PV technical experts and jointly funded by the MCS, the UK’s foremost renewable energy standards organisation, and the Fire Protection Association (FPA).


Recommendations for fire safety with photovoltaic panel installations – RC62 Revision – What you need to know.

On the 1st December 2021, a draft version of RC62 was issued to the UK solar industry for peer review.
The draft had already been reviewed by representatives of the UK Insurance industry.
The peer review process finishes on the 19th January 2022 and the final document will then be published as a pre-cursor to a Joint Code of Practice between the UK Solar & Insurance industries that will be published later in 2022.


Series Resistance Testing

The series resistance of a PV string system is the total electrical combined series resistance from the string ends connecting the inverter /optimiser and the module(s). When in darkness the PV cells have a high series resistance and in daylight healthy cells lower to a very low value of about 0.5 Ohms per module, and the connectors, junction boxes, cable all add a low but insignificant resistive value.


What’s the point of cleaning solar panels?

It’s quite a common question as there’s been quite a bit of misinformation thrown around about solar panel cleaning over the years. There’s three main reasons and they’re all to do with increasing output and protecting the investment made into having the panels installed in the first place. They are performance, safety and longevity,


Why you need to have your solar PV system regularly inspected & tested

Since 2008, there have been over 1 million rooftop solar PV systems installed in the UK, many in the days when Feed-in-Tariffs were the key driver to the industry.

Whilst the feed-in-tariffs were a huge incentive to have PV systems installed, the introduction of Feed-in-tariff digression dates, where the Feed-in-tariffs available dropped by over 85% in some cases, ensured that many PV systems were installed too quickly to meet the demand and were installed without the necessary care and attention to detail.

One common example, that is still being seen today, is the incorrect tightening of the DC connectors. When carried out correctly, there should be no thread showing which forms a water tight seal.

When not carried out correctly, the results can be devastating.


A report carried out by the Building Research Establishment (BRE) National Solar Centre found that the most common causes of rooftop PV fires are:

  • system design errors
  • faulty products being installed
  • poor installation practices

You can see the full report here.

Most insurers now insist that rooftop PV systems are tested and inspected annually to reduce the risks associated with poor installation practices. If you don’t have your PV system maintained annually, as well as the potential loss of revenue – you may face a much larger uninsured loss.

It is important to check with your insurer to see what your responsibilities are if you have solar PV installed on your property.

Discover the answers to everyday questions about solar PV maintenance below.

What (Gets inspected & tested during the service?)

MCS Certified and the Solar Trade Association both launched new maintenance guidelines in 2020 that covers exactly what items are to be tested during an annual maintenance visit. The main PV system components that are tested and inspected include:

  • Visual inspection of panels
  • Visual inspection of mounting frame
  • Testing of inverters – including fault notifications
  • Testing of electrical cabling (DC & AC)
  • Isolators and other ancillary equipment

Whoever carries out your solar PV maintenance will provide you with a full checklist of works that are to be carried out.

If you combine your maintenance check with a cleaning program, you will also be able to have a percentage of the PV module clamps tested to ensure that your panels are still secure.

Why (Do PV systems need to be tested and inspected?)

The main reasons to have your PV system maintained annually are to:

  • Maintain optimum system performance
  • Reduce CO2 emissions
  • Prevent small problems becoming large expensive problems
  • Comply with insurer’s requirements
  • Generate maximum revenue

You may also have your own reasons for maintaining your PV system.

When (Is the best time to have my PV system inspected?)

The main electricity generating months are April to September so ideally you will look to have your system inspected in the spring time to ensure maximum performance from your PV system. Sometimes though, unless you’re in a 3 or 5 year contract, you may need to have your annual maintenance scheduled outside of this peak period.


How (do I go about choosing the right company to do the testing?)

Choose a professional company that has experience in maintaining commercial solar PV systems and will supply you with written risk assessments and method statements. Usually a company that responds quickly to your requests will give you an idea as to how quickly they will respond should you get any problems with your system.

Sometimes it can be better to choose a company other than your original installer to carry out the checks otherwise you may be effectively asking the installer to check their own homework.

Where (Are Helios based?) Helios are centrally located in Ampthill, Bedfordshire, just off the M1, which allows us to get to most areas of England within 2 ½ hrs.

Who (do I choose to carry out the inspection?)

Helios recently helped to produce the UK’s first Rooftop O&M Best Practice Guidelines for the UK Solar Trade Association and are currently developing a Joint Code of Practice between the UK Solar & Insurance industries so have a wealth of knowledge to be able to assist you with your solar PV maintenance requirements, wherever you may be in the country.

Helios have also been extensively vetted for Health & Safety and Quality procedures by large international organisations and are currently providing PV testing and inspection services to Tesco & Amazon sites all across the UK.

There are other companies that also provide O&M services in different parts of the UK that you could also approach, Solar South West and Beba Energy have a similar service to Helios that you could try.

If you would like more information on Solar PV testing, inspection, maintenance or the efficient cleaning of your PV system, feel free to contact Robert Harley at Helios (company profile available to view here) on 01525 632238 today or via email at, where you will discover friendly impartial advice about how to look after your PV system.


Mark Bygraves has been appointed by Helios as a non-executive director

Helios Solar Operations & Maintenance is pleased to announce that Mark Bygraves has been appointed by Helios as a non-executive director, which took effect from 20th May 2021

Helios are one of the UK’s leading Solar Panel Cleaning & Maintenance companies and are the only specialised rooftop solar panel cleaning company in Europe to have been awarded ISO 9001, 14001 & 45001.

Mark is currently the CEO of Elexon, the company that oversees the strategic operation and day-to-day management of the Balancing and Settlement Code, a set of rules with which all electricity generators, suppliers, networks and other market participants have to comply.

Mark has over 20 years’ experience at the top levels in the UK energy sector having previously held positions as an investment banker, lawyer and commercial director at various energy companies.

Robert Harley, Director of Helios commented “We are delighted to have Mark on board with us, his wealth of experience at the top levels of the UK energy sector fits extremely well with our short and long terms plans for Helios. Mark joins us at an extremely exciting time in our business, having just been awarded ISO 9001, 14001 & 45001 and with our leading role in the development of the first Joint Code of Practice between the UK Insurance and Solar industries, it’s a pleasure to have Mark on board to help us to achieve our objectives”.

Solar Panel Cleaning by Helios? Good Call! 

Call us today on 01525 632238 or message to arrange a call to discover how easy it is to have your solar PV system cleaned, tested and inspected by the UK’s leading solar panel cleaning and maintenance company.

Mark (1)


Helios welcomes new team member, Chris

A big, warm welcome from Helios to Chris, our new member of the team.

 Here’s Chris, standing next to his new L200, in which he’ll be carrying out all of our HV/LV/EV & PV testing & inspection requirements, having gained a great deal of knowledge & experience at the Cape Town Electricity Generation & Distribution Department for the last 11 years.

We reckon that he’s going to be a “lekker” appointment!


Contact Helios today on 01525 632238 to discover the latest methods of testing and inspection to ensure that your PV system remains safe to operate.



Helios working with industry leaders to improve fire safety of PV systems

A recent report by the BRE in to the main causes of solar related fires identified mismatched and incorrectly installed DC connectors as one of the main causes of solar PV related fires.


Helios leading development of UK’s first Rooftop PV O&M Best Practice Guidelines

Helios have been working together with Wise Energy, Ecovision Asset Management, PSH Operations, the MCS and the Solar Trade Association in the development of the UK’s first Rooftop O&M Best Practice Guidelines.


Helios leading the UK solar market in applying correct temperature water

Helios conducted two experiments on the temperature of solar panels on the UK’s hottest day of the year when the thermometer reached 32.5°C.

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