Solar panel sizes and weights: how much roof do you need?
The size and weight of four current home solar panels, read from their datasheets, and how to turn those numbers into panels, kWp and a layout that fits your roof.
A typical home solar panel today measures about 1.72–1.76 m long and 1.13–1.21 m wide (roughly 5 ft 8 in–5 ft 9 in by 3 ft 9 in–4 ft), covers about 2 m² and weighs about 20.5–23 kg. That is what we found on the datasheets of four current residential panels, compared below. With those numbers you can work out how many panels a system needs, how much roof they cover and what they add to the roof's load.
Every model has its own dimensions, so the figures that count are the ones on the datasheet for the exact panel in your quote. If you are still deciding how big a system you need, start with how many solar panels you need.
Four current panels, measured from their datasheets
| Panel (datasheet edition) | Size (mm) | Area | Weight | Weight per m² | Power versions on the sheet |
|---|---|---|---|---|---|
| JinkoSolar Tiger Neo 54HL4R-B (F1.3-EN) | 1,762 × 1,134 × 30 | 2.00 m² | 22 kg | 11.0 kg | 420–440 W |
| LONGi Hi-MO X6 Scientist LR5-54HTH (V19) | 1,722 × 1,134 × 30 | 1.95 m² | 20.8 kg | 10.7 kg | 445–455 W |
| AIKO Neostar 2P AIKO-A-MAH54Mw (V4.1) | 1,757 × 1,134 × 30 | 1.99 m² | 20.6 kg (±3%) | 10.3 kg | 450–485 W |
| REC Alpha Pure-RX (IEC edition, Nov 2025) | 1,728 × 1,205 × 30 | 2.08 m² | 22.7 kg | 10.9 kg | 450–475 W |
A few things stand out, and they apply to these four panels only:
- Three share a width of 1,134 mm; the REC is 71 mm wider at 1,205 mm. Across six panels side by side that is over 40 cm, enough to change what fits between a roof's edges.
- All four are 30 mm thick. The mounting rails and brackets add to how far the array stands off the roof.
- Lengths differ by 4 cm, from 1,722 mm to 1,762 mm. Over a whole system that changes the total area very little, but on a short roof slope (eaves to ridge) it can decide whether a second row fits.
These are the manufacturers' international datasheets. A quote may offer a different power version or edition, so check the dimensions against the datasheet for the model code on your quote. To compare panels on more than size, see the best solar panels.
How much does a solar panel weigh per square metre?
About 10.3 to 11.0 kg per square metre for the four panels above, which is weight divided by area. That spread-out load is the figure that matters for the roof, more than the weight of one panel.
It covers the panels only. Rails, brackets and fixings add to it, as does ballast on a flat roof, and how much depends on the mounting system. Whether your roof can take the extra load is for a competent person to check. MCS-certified installers must have the roof structure checked before fitting panels. The MCS installation standard gives calculation methods for common trussed-rafter and gable-ended roofs, and requires a qualified structural engineer where the roof is unusual. That includes roofs with hips or valleys, signs of structural distress, removed or notched timbers, a switch to a heavier covering, a pitch below 30°, or features that let snow build up, such as dormers, valleys and parapets.
Ask for the quote to name the mounting system and to confirm that the structural check has been done for your roof.
How many panels, and how much roof, for 3 to 10 kWp?
kWp (kilowatts peak) is the panels' rated power under standard test conditions; kWh is the energy they actually produce over time. To reach at least a target size:
number of panels = target size in watts ÷ panel power in watts, rounded up
Taking the 440 W version of the JinkoSolar panel above as the example:
| Target | 440 W panels | Actual size | Panel area | Panel weight |
|---|---|---|---|---|
| 3 kWp | 7 | 3.08 kWp | about 14 m² | 154 kg |
| 4 kWp | 10 | 4.40 kWp | about 20 m² | 220 kg |
| 6 kWp | 14 | 6.16 kWp | about 28 m² | 308 kg |
| 10 kWp | 23 | 10.12 kWp | about 46 m² | 506 kg |
With higher-wattage panels you need fewer; with lower-wattage panels, more. That is why a quote that only says "4 kWp system" is incomplete: it should give the make, model and wattage of each panel, and the number of panels. Nine of these panels would give 3.96 kWp, just under 4 kWp, which may suit a roof where the tenth does not fit.
Panel kWp is not the same as inverter size. On a single-phase supply, the network operator notification route (G98 or G99) depends on the inverters' combined AC output, battery inverters included, with 3.68 kW as the single-phase G98 limit, not on the panels' kWp. So a 4.40 kWp array can be paired with a 3.68 kW inverter. G98 and G99 explains the difference.
My yearly electricity use is
Your yearly electricity use helps us size your solar panel system.
Why the usable roof is smaller than the roof
The areas in the table are the panels added together. The roof also has to leave room for:
- Gaps at the edges. The MCS standard says panels should not be mounted within 400 mm of any edge of a domestic roof unless specific measures are taken to resist the stronger wind uplift near the edges, keep ridge tiles secure, avoid changing rainwater run-off, stop snow shedding causing harm and reduce wind noise.
- Gaps between panels for the clamps, as set by the mounting system.
- Obstacles and their shadows: chimneys, dormers, roof windows, vent pipes and aerials. Shading can rule out more of the roof than the obstacle itself covers.
- Rows on a flat roof, where tilted panels need space so they do not shade each other.
An example: portrait or landscape on the same roof
Take a rectangular, unobstructed roof slope 8.0 m wide and 5.5 m from eaves to ridge, and the 1,762 × 1,134 mm panel above. Leaving 400 mm at every edge gives a usable area of 7.2 m by 4.7 m. Assuming a 20 mm gap between panels (an illustrative figure; the real gap depends on the clamps):
| Layout | Across the roof | Up the roof | Panels | Size with 440 W panels |
|---|---|---|---|---|
| Portrait (long side up the slope) | 6 (6.90 m) | 2 (3.54 m) | 12 | 5.28 kWp |
| Landscape (long side across) | 4 (7.11 m) | 4 (4.60 m) | 16 | 7.04 kWp |
On this roof, turning the panels gains four more. On another roof, portrait may win. This is an illustration, not a design: rafter positions, the mounting system's rules and any obstacles decide the real layout. Ask the installer for a layout drawing before you sign (MCS-certified installers must give you one), showing both orientations if the mounting system allows them.
Why panel efficiency matters when roof space is tight
A panel's efficiency is the share of the sunlight hitting it that it turns into electricity. In practice it decides how many kWp fit on the roof space you have: for the same area, a more efficient panel gives more power.
The four datasheets give 22.02% for the 440 W JinkoSolar, 23.3% for the 455 W LONGi, 24.3% for the 485 W AIKO and 22.8% for the 475 W REC. These figures belong to each model and power version, not to the brand: lower-wattage versions of the same panel have lower efficiency.
If you have plenty of roof, efficiency matters less than the price of the whole system per kWp. If the roof is small or broken up by obstacles, it can decide how big a system you can fit at all.
What panel size and weight mean for installation
- Getting panels onto the roof. Carrying panels of over 20 kg at height is a job for an installer with proper access, which on most houses means scaffolding. See scaffolding for solar panels for what to expect on a quote.
- Orientation of the panels changes how many rows fit on a given roof, as the example shows, and should be decided from a survey.
- The added weight comes on top of the existing roof covering. On an older or altered roof, the structural check comes before the choice of panel, not after.
- How far the array projects matters for planning. In England, permitted development for panels on a pitched roof requires them not to project more than 0.2 m beyond the roof slope, among other conditions; rules differ in Scotland, Wales and Northern Ireland.
When you compare offers, set the panel model, number of panels, layout drawing and mounting system side by side; comparing solar quotes shows what else to line up.
Frequently asked questions
What size is a standard solar panel in the UK?
There is no single standard. The four current residential panels we checked measure 1,722 to 1,762 mm long; three are 1,134 mm wide and one is 1,205 mm, all 30 mm thick. That is just under 2 m² each, or a little over for the wider panel.
How much does a solar panel weigh?
Between 20.6 and 22.7 kg for the four panels above, or 10.3 to 11.0 kg per square metre for the panels alone. Rails, brackets and fixings add to that.
How much roof space do I need for a 4 kWp system?
With 440 W panels of about 2 m² each, 10 panels give 4.40 kWp and cover about 20 m². The roof needs more than that once edge gaps, clamp gaps and obstacles are allowed for; a survey gives the real figure.
How many solar panels fit on my roof?
Work from the roof's dimensions (from plans, the loft or a measurement taken from the ground; do not go up on the roof), take off 400 mm at each edge (unless the installer uses the extra measures the MCS standard allows), then see how many panels fit in portrait and in landscape. Chimneys, roof windows and shade reduce the count. An installer's layout drawing is the reliable answer.
Can my roof take the weight of solar panels?
That needs a structural check by a competent person, which MCS installers must arrange before fitting. Unusual roofs, such as those with hips, valleys, signs of distress or a heavier replacement covering, need a structural engineer.