Installing solar panel optimisers? Choose the right scaffold.

Very little weight goes up on this job, but a great deal of small stuff does: a box of units, cable ties, a cordless driver, a marker and a clipboard carrying the roof plan. You want that lot lying beside you, not swinging in a bag off the guardrail. So the choice falls on the RS52, the wide 135 cm base, where a crate can stand on the deck and you can still walk past it. Every base you can reserve is gathered in the range of mobile scaffolds for hire.

The narrow RS51 at 75 cm will do as well, and it is what you pick when the tower has to pass between a shed and a hedge to reach the back. You trade away deck area for that, exactly where the kit was meant to live. A MiTower is built for one person and stops at 6.2 metres, so a roof at ten metres rules it out. A room scaffold belongs indoors. What is left is a wide tower moved along the gutter in a handful of positions.

Before you hire a mobile scaffold for this, think about where you step onto the roof. Installing solar panel optimisers on a pitched roof usually means standing on the tower and reaching over the gutter to the bottom row, while the rows above it call for going onto the tiles. The platform is then your starting point, your store and the place the roof plan lives. A wide deck makes that transfer a good deal calmer than a narrow one, particularly on the way back with both hands full.

The point you have to reach is the lowest mounting rail, and that sits a short way above the gutter. So measure to the gutter and add half a metre. The figure you enter when reserving is a working height, made up of the platform height with the roughly 2 metres your arms bridge on top. On a house of two storeys with a pitched roof that brings you out at eight to ten metres. With three storeys it climbs towards twelve, which is the top of this band.

That puts you squarely in the 8 to 12 metre range, and that is what installing solar panel optimisers asks for. To see which build matches, look at a build for ten metres of working height and count up how many platforms come with it. What you should not do is measure to the ridge: the top row of panels is reached across the roof rather than from the tower, so that height need not be hired at all. It saves you frames and assembly time.

Hiring a build that is too low works out badly here. Standing under the gutter, you reach up under the panels with arms fully extended and the bracket never seats properly, so more time goes into wrestling than into fitting. And if you do have to get onto the roof, you want your hip at gutter level as you step across, not to be hauling yourself upward. One extra platform costs almost nothing when you reserve; a second rental period costs a good deal more.

Panels lie on whichever pitch catches the sun, and that is by no means always the side with a drive. More often than not you end up in the back garden, on grass or on a terrace, with a shed or a summer house in the way. Walk that side before reserving anything and see whether a level patch of a few metres can be cleared, with room for the four stabilisers that reach out into the planting. Where there is a terrace, that is usually the best spot for installing solar panel optimisers from.

Grass is the most awkward ground of the lot. The castors sink in the moment it has rained a day, and then the tower no longer stands level while you are up there dealing with small components. Put trackway or thick boards under the feet and take up the rest on the spindles. Tightening a bracket demands precision, and precision does not come off a deck that gives. Setting a tower on ground like that is described in the piece on uneven ground.

Look at what hangs above the standing spot too. The flat roof of an extension, an awning or a branch from next door gets in the way more often than you expect, and you meet it only when the tower is half built. Work out as well where the box of units and the plan may live; a garden table beside the position does nicely. Tell the neighbours you will be along the boundary for a couple of days, which saves a discussion halfway through your hire.

The fitting itself moves along: clipping a box onto the rail, pushing two pairs of connectors home and looping through to the next takes only minutes per plate. The time goes into raising the tower, shifting it along the gutter and keeping the paperwork straight. For a roof of ten to fifteen plates you therefore hire one to two days, of which the first half day disappears into building. Where a second pitch on the other side also carries panels, add another day.

A spare day like that hardly registers on the bill. Full price applies to the opening twenty four hours alone, while every following day arrives with ninety five per cent taken off it, so a roomy reservation is close to free. Whatever rental price goes with your particular build is set out with VAT on the page of tower rates. Installing solar panel optimisers is not work to break off halfway, so take the longer booking and finish the array in one visit.

The weather plays its own part. You fit these units with the installation switched off, and you would rather not do it on a blazing afternoon, when the plates are too hot to handle and the rail burns your fingers. Rain is a different problem, since connectors want to be made up dry. Pick an overcast, dry day and keep a fallback day inside the booking. As the collection date is yours to choose, that fallback day costs you very little.

A platform of 245 cm covers about two panels across. Each position therefore deals with the boxes for two plates, perhaps three: bracket onto the rail, unit into the bracket, leads up and across. After that the tower has to travel a little further. On a roof of fourteen plates, count on something like six positions, and that is precisely why the plan goes up with you: after the fourth move nobody remembers which number belongs where on the roof.

The looping through decides how you work along the gutter. Every optimiser has a short output to the next one, so you follow the order of the string rather than jumping about the roof. Lay each lead neatly into the clips beneath the rail as you go, because a loop left sagging cannot be retrieved from the ground afterwards. Anything you leave hanging costs you a further position, which means braking, setting the stabilisers out and climbing all over again.

The stickers are where things go wrong most often. From every unit you peel the serial number and press it onto the spot on the plan where that plate lies. Do it there and then, from the platform, and never afterwards from memory once you are back on the ground. Clamp the sheet to a clipboard and tuck it inside your jacket at every move, because a gust along the gutter takes loose paper off into the garden and the hunting starts. Paper and wind get on badly at this height.

The set arrives counted and complete, and you decide where it may lie. On optimiser work the tower usually ends up round the back, so point out a spot at the front where the van can unload and from which the parts go through in two or three trips. If the order is in the system by 15:00 on a weekday, the following working day is the earliest the set can stand at your door. Put the delivery a day ahead of your start.

Assembling the tower is your part; we do not come and build. A manual travels with the parts and the sequence is filmed as well; two people get a build of this height standing inside a couple of hours. Raise it the day before you begin, so the next morning opens with a working position instead of you waiting about with a box of units in your hand. Keep that assembly session as its own slot, because no bracket goes on the rail while it runs.

Once the final box hangs and the plan is complete, you strip the tower and stack the parts where they were unloaded; on the agreed day we drive round to collect them. Check beforehand that no cable tie or connector cap has stayed behind between the platforms. What the journey out and back comes to varies by province, and the figure with VAT sits under delivery charges by province, so the total is known before you reserve.

Load class 3 means the deck may bear 200 kg on each square metre, and that class comes from EN 1004. On optimiser work you get nowhere near it: a box of units weighs almost nothing. What does count is that two of you are often up there at once, one on the tower and one on the roof, with tools and a crate between you. There is more about that in this explanation of the standard for mobile towers.

The usual agreements apply here as well: brake the castors first and climb second, nobody aboard while the tower travels, and the work goes down when it starts to blow. Wind is a particular nuisance on this job, because stickers, roof plans and loose caps are the first things to go. Set all four stabilisers out again after every move, even when you have only shifted the width of one plate; that is exactly the moment people skip it.

The risk peculiar to installing solar panel optimisers is small items falling. A cap, a screw or an offcut of trunking coming down from ten metres is more dangerous than it sounds, so keep the ground under the tower empty and use a tool bag that closes. Work only on an installation that is switched off, and leave the connecting to somebody trained for it. Post somebody below to keep watch if there are children playing in the garden. Further rules sit on the page about working at height.