Roof Access Solar PV

This blog considers the importance of including a long-term roof access strategy in the design of commercial Solar PV, and primarily focuses on access to low-pitch and flat commercial roofs. I will consider how guard rail and roof safety line solutions can provide a safe means of access and how this impacts the layout of the solar array.  This blog does not apply to fragile roofs like glass fibre cement roofs.

Roof Full of Solar PV Leaves No Room For Access

Solar PV installation companies have a duty under Construction (Design and Management) Regs 2015 and to their clients to ensure adequate means of access have been allowed for as part of any commercial Solar PV installation.  This is also an opportunity to ensure the client can access any other areas they need to maintain and add value for the client.  I have lost count of the number of times clients have approached me to provide them with a means of safe roof access, only to show me a roof completely covered in solar panels!  I have experience of the Solar PV industry myself and fully understand the desire to get as much out of the roof area as possible. But with a PV system comes the ongoing need for inspection, testing, maintenance and cleaning.  The end user is left with a headache if the future access requirements are not considered at the design stage.  It may also be the very same company that installed the Solar PV that will be left with the problem of safely maintaining it going forward! Worse still, I have seen systems that have denied the building maintenance team means of access to other areas of the roof, such as the gutter.

How to Design-In Roof Access?

The roof access should be considered in partnership with the building owner and take into consideration their resources, skill sets and preferred methods.

1. How will people get onto the roof and from what location? Consider a staircase, Cherry picker, Internal or external fixed hooped ladder, fixed ladder with integrated fall arrest system, or lashed temporary ladder. See my previous blog on this subject. Note, on larger roofs, you may need more than one point of access and egress in case of a fire!
2. Identify all fall hazards at the edges.  A parapet or guard rail only provides adequate edge protection if it reaches 1100mm in height.
3. Identify all fall hazards from voids. Smoke vents and extractors may not pose an immediate fall risk, but may sometimes be opened up.
4. Identify all fall hazards from fragile surfaces. Fragile surfaces are a real hazard. Especially the inline roof lights you find on metal roofs. These can be hard to see and are easy to stand on accidentally!  Any metal roof inline roof-light pre-2000 could have been fragile from the day it was installed.  Anything post-2000 should have a non-fragility rating at the time of install.  However, these become fragile over time.  I have seen 15 years stated as the kind of time span it takes for some of these to become fragile, but there is no absolute rule and it will vary between products and different environments.  If you cannot prove a rooflight is non-fragile (which is very difficult to do), then assume it is fragile.  Likewise, on flat roofs, any raised dome lights that are made of glass or other material should be assumed fragile unless you have evidence otherwise.
5. Decide on which areas of the roof will require access. The simplest answer to this would be ‘all of it’.

Once you have addressed all the above points, you are in a position to start to formulate your access strategy.  This should be realistic.  Specifying full scaffold for routine inspection and maintenance on a Solar PV array is usually not the most cost-effective solution.

Access Plant

Access plant such as a cherry picker, although coming at a cost, can be used to access a roof and is a good option for maintaining gutters, where terrain allows.  With the correct equipment, in some cases, they can also be used for access for cleaning roof-mounted solar arrays.  This depends on the terrain, array size and the access plant used.  A cherry picker is not a realistic way of performing a detailed inspection of an on-roof array.  On a relatively flat roof,  you could not realistically directly replace a roof-mounted panel from within the cage of a cherry picker. This would involve leaning out of the cherry picker guarding, which is not correct practice.  Furthermore, the cherry picker cage could cause damage to the array.

Access Routes

What will be the main routes across the roof?  Whilst some panels may be classed as walkable, they are hardly a safe high-friction surface.  As a minimum, leave a route clear of panels.  At best, install a walkway.

Collective Protection of Fragile Surface

For potentially fragile in-line roof lights on metal roofs, excellent fall-proof wire mesh covers can be permanently installed.  Covering these should be a priority as the in-line roof lights are especially hazardous.  Even if you install a fall arrest system, the potential of someone falling through a roof light is hardly a satisfactory outcome in terms risk mitigation.  There is also the issue of fall clearance.  A fall arrest system needs at least 6.5m clearance below it to allow for the fall arrest process and a safety margin.  This is rarely available, so protecting the roof lights with fall-proof covers is a very important measure.

For domed roof lights, we have fixed and free-standing guard rail-type protection.

Collective Protection – Roof Guard Rail Solar PV

The Working at Height Regulations 2005 require us to give first consideration to collective protection.  This means barriers that protect everyone and do not require special equipment or training.  So, consider protection of all exposed edges and fragile surfaces with guard rail.  On flat roofs, free-standing guard rail is very easy to have installed, and because it uses counter-weights, there is no penetration of the roof.  You must allow at least 1.4m between the roof edge and Solar PV for the counterweights, usually placed at 5m centres.  There are versions of free-standing guard rail that have less of a return on the weights, but you will pay premium price for these.  Where no parapet or a parapet less than 150mm is in place, you can add a toeboard to the guard rail to prevent objects from rolling off the roof.  Guard rail can also be easily fixed to metal sheet and standing seam roofs without impacting on the roof integrity.

Collective edge protection has the disadvantage of impacting aesthetics and comes with a higher price tag.  It also adds additional loading onto the roof ontop of the already increased loading imposed by the Solar PV.  For these reasons, in some cases, it may be decided to opt for Personal fall restraint systems such as roof safety lines.

NB I have never seen an assessment of the shade implications of guard rail on Solar PV.  If anyone has any information on this, I would be interested to see it.

Personal Fall Protection –  Roof Fall Arrest Solar PV

Safety Line to access Solar PV

There are excellent roof safety lines that allow for continuous attachment and are quick and inexpensive to have installed.  Although I have titled this section ‘Roof Fall Arrest’, in reality we will design to achieve restraint i.e when used correctly a fall is not possible. The simplest way to protect against falls from a roof is to run a safety line all the way around the perimeter and set 2.5m back from the edge.  This usually allows the gutters and the outside of the solar to be maintained via connection with a 2m lanyard whilst maintaining restraint i.e. a fall is not possible.  This also provides safe zone demarcation.  When operating within the safe zone demarcated by the line, there could be no need to be connected. On a relatively flat roof, if you have taken care of fragile surfaces, this could be the only personal fall protection you need.  If implementing this strategy, the solar panels will need to be set 2.8m back from the edge, which is space you may prefer to be covered in solar panels, but from an access point of view, it works.  On a shallow-pitch roof without any remaining fragile surfaces, that may be sufficient. However, some clients would prefer that anyone on the roof is permanently anchored.  In this case, you will also need a central/ridge line that can be used with an adjustable rope and grab or a retractable fall arrest block.

If you do not opt for a total perimeter safety line system, consideration needs to be given to protection against swing falls.  A ridge line on a roof with gable ends leaves the potential for a fall off the gable end with little or no protection.  Lines set 2.5m back from the gable ends will provide safe zone demarcation and a continuous anchor point that provides restraint when used with a 1.8m lanyard.  Solar panels will need to be set 2.8m back from the edge to allow for this.  There are perhaps more complex methods to achieve personal fall protection if the panels must be nearer to the edge, but these are less self-explanatory and are open to misuse if not carefully managed.  O&M information is often misplaced or ignored, so the simpler the solution the better!

So, there is a lot to consider but hopefully, this will be a good starting point for end clients and Solar PV designers.  You can always contact a fall protection expert to assist regarding the big picture or the final details.  By considering roof access at the design stage of a Solar PV project, problems can be avoided and safe access to both the roof and the Solar PV system can be built in.

Subscribe to get my take on using access equipment to install Commercial Solar PV in my next blog.