Fitting solar panels? Choose the right scaffold.

For fitting solar panels you hire the Altrex RS52, the wide model with a 135 cm working deck. You genuinely use that width here, because the mounting material lies beside you while you work: a bundle of rails, a box of roof hooks, the mid clamps and end clamps and a cordless driver with its bits. On a narrow floor you are forever sliding all of it aside to get past. What else stands ready is listed under the towers available to hire from us.

On a pitched roof the tower stands along the gutter and you work over the roof edge inwards. You lean forward while you do it, and a broader floor is a great deal more pleasant then: behind you there is still a clear strip where nothing lies and where you can move a foot. Fitting solar panels also usually means two people up top, since a sheet of nearly two metres is awkward to lay on the rails on your own.

If the route to the back of the house is full of obstacles, a narrow gate or a path between two fences, only the 75 cm wide RS51 will get through. You give up deck space by doing so, so measure that passage before you reserve anything. For the fixing work itself the wide build remains the better choice in almost every case. Which build suits which roof is worked through in the piece on the right tower for a solar array.

Your highest working point is the top row of roof hooks, and that sits a fair way above the gutter. Measure to that line, then, and not to the roof edge. On top of the platform height comes another 2 metres or so of reach, because that is how high you get standing with your arms up. For a two storey house with a pitched roof that puts the working height somewhere between 8 and 12 metres, depending on the pitch and on where the top row lands.

Your measurement starts at the ground beneath the castors, not at the threshold of the back door. A garden that falls away towards a ditch, or a sunken patio, easily costs you half a metre that you never make up later on. If the roof faces the street and the tower stands on the pavement, you measure from the paving. What that means in parts and lifts is set out under a ten metre working height, which sits in the middle of this band.

Build too low and you end up at the top row with your chest against the roof edge, levelling the rails by feel. That comes back at you immediately: a rail a centimetre out of true shows up across five panels as a crooked edge. One lift higher costs a few extra parts and half an hour of building; starting too low costs you a whole extra set up. If you sit between two builds on a roof at second floor level, take the higher of the two.

For this job the tower almost always ends up in the back garden or on the drive, because that is usually where the roof slope with the array sits. Before delivery, work out where you can put it on flat, load bearing ground. Paving and blockwork are fine; a lawn that gives way under the castors after a wet week is not. If the garden lies lower than the patio, allow for that step when you level the base. Measure it rather than guessing at it.

At the foot the ground has to be sound as well as flat, since all four stabilisers press down through small feet that sink into anything soft. On a rear elevation that space is usually full of the fixtures that live there: a water butt below the downpipe, the outdoor unit of a heat pump, a border of tall planting or a canopy that runs out a metre from the wall. Clear all of that before the parts arrive.

Do not push the tower hard against the gutter but leave a hand's width, or the top guardrail will not pass when you move along. If you work a roof in rows you shift a little way along the elevation for each one, and that goes fastest when no slab is loose and no hosepipe lies across the route. Walk that strip once from end to end before you first climb up. What to do on a slope is covered in the notes on uneven ground.

A set of ten to fourteen panels on a pitched roof takes two people about three days, and most of that time goes at the start. First you set the grid out: you stretch a string line across the width of the slope, count off the rafters and decide where each hook lands. Only when that line is true do you screw the first hooks down. Rush it and you correct it later along the whole row, which costs a hire day of its own.

Then comes the number of set ups. A roof slope eight metres wide takes three or four positions, and each move costs a good half hour once you have cleared the deck and stabilised again. There are also waits that are not yours to control: the installer who connects the inverter comes on his own day, and on wet tiles or in a stiff wind you stand still. Plan your period on the date you would still make with setbacks. Nobody plans for a wet Tuesday, yet everybody meets one.

Planning generously costs little. The first day of the hire carries the full amount; each day you add after it is cut by 95 per cent, which leaves a fourth or fifth day almost invisible on the total. Book too tight and the van is at the door while the top row still lies loose, and then you really are stuck. How to judge the length of a period is set out in the guide to the number of hire days. A spare day at the end is worth more than an early start.

Each position gives you 245 cm of platform length, and that sets your rhythm. From one set up you reach roughly two panels side by side plus the hooks that belong to them. Start at the top of the row with the setting out: lay the string line horizontally across the tiles, lift the tile above each hook position and find the rafter or batten the hook screws onto. Finish that whole strip before you move, because coming back to a position costs double.

Onto the hooks go the aluminium rails, and two things there have to be visible from the deck. Aluminium expands in the sun, so long runs get a joint between two rail lengths instead of a hard coupling. And every panel has a clamp zone from the manufacturer: a band along the long edge within which the mid clamp and the end clamp must sit. Clamp outside it and the frame carries the load in the wrong place entirely.

The third point is the distance to the roof edge. At the edges and in the corners of a roof the wind pulls hardest at a panel, so you keep a strip clear there and move the whole row towards the middle. That sometimes changes your layout while you are already at work, and then a wide deck lets you shift a row without stripping everything back. If the sheets still have to reach you, read on about the handover of panels at gutter level.

What arrives is a complete, counted set of parts: uprights, diagonals, platforms, guardrails and the stabilisers loose alongside. If your order leaves before the 15:00 deadline on a weekday, it is delivered the working day after. Agree in advance which square metres that stack lands on, because the strip along the elevation is needed for the panels themselves. A corner of the drive suits far better than the grass under the roof slope. Mark that spot out with a couple of pallets if the drive is shared.

The build is your job, with the manual and the instruction video to guide you through the order. Two hours of work for two people gets you to this height, so set the delivery for the day before your first fixing day. You choose both the delivery date and the collection date, which suits solar work because the panel shipment is rarely nailed down. If that delivery shifts, the tower shifts with it. Which part goes on when is laid out in the step by step build.

We come to collect the tower at the end of your period; you take it apart and put the parts together in one place. Do not leave that to the morning itself, in among clearing cable trunking and packaging, because that is exactly when a brace goes missing under a pile of film. Count while you dismantle, not once everything lies on the pavement. The amount for bringing and fetching depends on which province you are in and is listed under the delivery charges per province.

The deck under you will take 200 kg on any one square metre, a figure that comes straight from class 3 of the EN 1004 standard. With solar work you reach that limit sooner than expected: a panel weighs a good twenty kilos and there are usually two people on the platform. So do not lay the whole stack of rails and sheets up there, only what that one set up needs. What that means in practice is covered in the notes on load and weight. Take up only the rails that row actually swallows.

The basic rules apply in full. Brake every castor the moment you step on, never move the tower with anybody or anything on the deck, and stop when the wind picks up. That wind limit arrives sooner here than on other roof work, because a panel carried upright behaves like a sail. After each move fold the four stabilisers out again and check that all four touch the ground; on block paving one of them likes to drop into a joint. Lay a scrap of ply over that joint before the foot goes down.

What actually goes wrong while fitting solar panels usually involves the small parts. A mid clamp or a bolt that rolls off the roof edge arrives on the ground at speed. So keep the strip under the platform clear and stand a cone or a barrow there if children are about in the garden. Do not work on the cabling while the array lies in full sun, and never step from the guardrail onto the tiles. Wet pantiles give way before you notice.