Solar Panel Dimensions UK

A standard UK residential solar panel measures 1,762mm by 1,134mm by 30mm and weighs 20 to 21kg. That is 1.76 metres tall, 1.13 metres wide, about the size of a single mattress, and just under 2 square metres of area. Current panels of that size are rated between roughly 415W and 460W.

What makes this useful is that the size barely varies. The 1,762 by 1,134mm module has become the de facto residential standard, so a quote for 440W panels and a quote for 415W panels will almost always cover the same area of your roof. The wattage differs, the footprint does not.

Below: the exact figures from two manufacturers' own datasheets, what a panel weighs per square metre and what the MCS standard makes your installer do about it, the 30mm thickness against England's 200mm planning limit, and a worked example of how a 36 square metre roof slope ends up holding 12 panels rather than 18.

How big is a standard solar panel in the UK?

1,762mm by 1,134mm by 30mm, weighing 20 to 21kg, is the size you will be quoted on the overwhelming majority of UK homes. Here are the published figures from two of the manufacturers whose modules turn up most often on British roofs, taken from their own product pages today.

Sources: JA Solar JAM54S30 LR product data and Trina Solar Vertex S+ rooftop portfolio, both checked 9 September 2026.

Two things fall out of that table. The first is that the residential modules share a footprint to the millimetre, which is why panel dimensions are rarely the deciding factor between quotes. The second is that the larger 510W module is longer, not wider, and 2.5kg heavier. It is aimed at commercial roofs, and on a house it usually costs you a row rather than saving you one.

For context on what fills that area, our guide to solar panel types in the UK covers monocrystalline, N-type and the rest, and solar panel efficiency explains why the same 2 square metres now produces far more than it did ten years ago.

How much does a solar panel weigh?

A standard panel weighs 20 to 21kg, which works out at about 10kg per square metre before you add the mounting rails and clamps. A 12 panel array is therefore roughly 250kg of glass and aluminium, spread over about 24 square metres of roof rather than concentrated in one spot.

In the units a structural engineer uses, 21kg over 2 square metres is close to 0.10 kilonewtons per square metre. That matters because of how the MCS standard tells installers to check the roof. MIS 3002, the solar PV standard every MCS certified installer works to, says at clause 5.9.4 that "the MCS Contractor shall ensure that the roof structure is checked by a suitably competent person to ensure it can withstand the loads imposed by the solar PV system".

The method sits in the standard's Table 1. For a roof built from timber trussed rafters, which covers most post-war UK housing, it says to assume "a typical design dead load of 0.785kN/m2, deduct the load of the existing roof covering to give the maximum allowable residual load available for the solar array". So the question is never whether your roof can hold 250kg in the abstract. It is how much of the original design allowance your existing tiles have already used up.

That is also why swapping heavy concrete tiles for lighter panels is a different job from adding panels on top of them, and why clause 5.9.6 requires "a qualified structural engineer shall be consulted" wherever the roof structure is unusual, which the standard's note defines to include any roof not shown in Table 1, one showing signs of distress or post-construction modification, or one where the pitch is "particularly shallow (i.e. less than 30° to the horizontal)". Source: MCS MIS 3002 Solar PV Systems, Issue 6.0, 18 March 2026.

How thick is a solar panel, and does 30mm matter?

The panel itself is 30mm thick, but the number that matters in England is 200mm, and it is measured from the roof slope to the top of the installed equipment. That measurement covers the panel plus whatever it sits on.

The Planning Portal states the permitted development limit plainly: on a pitched roof, panels "should not be installed above the highest part of the roof (excluding the chimney) and should project no more than 200mm from the roof slope or wall surface". On a flat roof the highest part of the equipment "cannot be more than 600mm higher than the highest part of the roof". Source: Planning Portal, solar equipment mounted on a house, checked 9 September 2026.

A 30mm panel on a standard on-roof rail system sits comfortably inside 200mm. Where the limit bites is on a pitched roof where someone proposes tilting the panels up to face a better direction, or on a shallow slope where a frame is used to steepen the angle. Both can breach 200mm and turn a permitted development job into a planning application.

Those numbers are for England. Scotland, Wales and Northern Ireland write their own limits, and they are not the same: Scotland allows 1 metre of projection on a dwelling, and Northern Ireland allows 1.5 metres above a flat roof. The four-nation breakdown is on our solar panel planning permission page. If you are looking at a flat roof specifically, the ballast and tilt maths is on solar panels on a flat roof.

One alternative removes the projection question entirely. In-roof panels replace the tiles rather than sitting above them, so the array finishes flush with the roof surface.

How much roof space do you need per panel?

Allow 2 square metres per panel of panel area, then expect to lose a good chunk of your roof before you start counting. The Energy Saving Trust puts it in the same terms: "A 4.5kWp system typically covers between 20 to 30m2 of roof surface area, typically using around 12 panels" (Energy Saving Trust, solar panels, last updated 27 August 2026).

Notice the spread. Twelve panels are 24 square metres of glass, yet EST's range runs to 30. The extra is the real roof: chimneys, vent pipes, roof windows, hips and valleys, and above all the margin around the edges.

That margin has a number attached to it. MIS 3002 clause 5.9.7 says solar modules "should not be mounted within 400mm from any edge of a domestic roof unless specific measures are taken" to resist the higher wind uplift in the edge zone, keep ridge tiles secure, avoid changing rainwater run-off and stop snow building up dangerously. Installers can and do work inside that 400mm with extra fixings, but the default is a 400mm strip out of every side.

A worked example

Take a rear roof slope 8 metres wide and 4.5 metres from eaves to ridge. That is 36 square metres, which sounds like 18 panels.

• Take 400mm off each edge and the usable rectangle becomes 7.2m by 3.7m, or 26.6 square metres.
• In portrait, each panel occupies 1.134m of width and 1.762m of slope. That is 6 columns across (7.2 ÷ 1.134) and 2 rows up (3.7 ÷ 1.762). 12 panels.
• In landscape, each panel occupies 1.762m of width and 1.134m of slope. That is 4 columns and 3 rows. 12 panels again.

Twelve panels at 440W is 5.28kWp, on a roof whose raw area suggested 18. The 6 missing panels are the edge zone and the arithmetic of fitting rectangles into a rectangle. This is the single biggest reason a self-measured estimate comes in high, and why installers survey before they commit to a number.

Now shrink it. A 6m by 4m slope is 24 square metres, but after the edge margin you have 5.2m by 3.2m, and 3.2m will not take two rows of portrait panels (that needs 3.53m). You get one row of 4, or 2 by 2 in landscape. Four panels from 24 square metres of roof. On slopes shorter than about 3.6m, whether the second row fits is the whole ball game, and it is worth asking an installer directly whether reducing the edge zone with additional fixings would gain you a row.

For sizing by electricity use rather than by roof area, start with how many solar panels you need, then price it on the solar panel cost page.

How to measure your roof for solar panels

You need two numbers per roof face: the width along the eaves, and the slope length from eaves to ridge. Neither requires going up a ladder.

1. Width. Measure along the ground at the base of the wall, or count the bricks along it and multiply. A standard UK brick is 215mm long and sits in a 10mm joint, so 4 bricks along a wall is very close to 900mm.
2. Slope length. If you know the roof pitch, the slope is the horizontal run divided by the cosine of the pitch. At a common 35 to 40 degrees, the slope is roughly 1.22 to 1.30 times the horizontal run from wall to ridge line.
3. Subtract the obstacles. Mark chimneys, soil vents, roof windows and satellite dishes. Panels cannot span them and installers will not shade a string with them.
4. Take 400mm off every edge before you count panels, for the reason above.
5. Divide. Try both portrait and landscape. Whichever gives more whole panels is usually what an installer will propose, subject to how the panels string together electrically.

Treat the result as an upper bound. The survey stage exists because rafter spacing, tile condition and the position of the consumer unit all move the answer, and MIS 3002 requires accurate shading assessment that "will typically require a site visit".

Do bigger panels give you a better system?

Not on a house, no. What matters is watts per square metre, not the size of the individual panel. A 440W panel over 2.00 square metres delivers 220W per square metre. That is the same thing as the module efficiency figure on the datasheet: 22.0 per cent efficiency means 220W from the 1,000W per square metre of standard test conditions.

Current residential modules run from about 22.0 to 23.0 per cent efficiency, so on a fixed roof area the practical difference between a good panel and a great one is a few hundred watts across a whole array. The larger 510W module is more powerful per panel purely because it is a bigger panel, at 22.9 per cent efficiency, so it does not fit more generation onto the same roof. On a domestic slope its extra 199mm of length is more likely to cost you a row than to gain you output.

Where panel size does change the answer is at the margins of a roof: an awkward slope, a dormer, or a garage roof where one more column of panels fits only if the panels are narrow. That is a layout question for the surveyor, not a spec-sheet question for you.

What about output, given the area?

A well-oriented UK roof produces roughly 800 to 950kWh per year for each kWp installed, using the Kk factors from the MCS standard's zone tables, higher on the south coast and lower in northern Scotland. Put the two together and a square metre of well-sited panel generates in the region of 175 to 210kWh a year.

An east or west facing roof "tends to get around 15-20% less energy than one facing directly south", per the Energy Saving Trust, which does not recommend north-facing installations at all. So an extra row of panels on a south slope is worth more than two extra rows facing east, and roof area alone never settles it. Our page on which direction solar panels should face has the detail.

Solar panel dimensions: frequently asked questions