For most UK homes, solar panels produce strong year-round results at an angle of approximately 30–40° from horizontal. However, your roof does not need to match this range exactly to be suitable for solar.
Panels installed on a conventional pitched roof normally follow the existing roof slope. Changing their angle by a few degrees is unlikely to justify a more complicated mounting system.
Flat roofs require a different approach. The installer must balance the output from each panel against row spacing, shading, wind exposure and the number of panels that can fit.
The short answer
- Around 30–40° is an excellent UK benchmark.
- Roofs outside this range can still be highly suitable.
- Direction, shading and available space can matter more than a modest difference in pitch.
- On a flat roof, the best angle for one panel may not produce the most electricity from the whole roof.
If you are assessing the property as a whole, start with our guide to solar-panel suitability.
What does solar-panel pitch mean?
Solar-panel pitch, inclination and tilt all describe the angle of the panel above a horizontal surface.
The angle is measured from horizontal:
- 0° means the panel is completely horizontal.
- 15° means it has a shallow upward tilt.
- 30° means it is tilted 30° above horizontal.
- 45° is a relatively steep roof angle.
- 90° means the panel is vertical.
This is also how panel inclination is recorded under the MCS method used for UK solar-generation estimates.
Roof pitch and panel pitch are related, but they are not always the same measurement.
On a conventional pitched roof, the mounting rails normally hold the panels at approximately the same angle as the roof. On a flat roof, mounting frames can position the panels at a different angle from the roof surface.
What is the best roof pitch for solar panels?
A south-facing array pitched at approximately 30–40° provides a strong balance between summer and winter generation across much of the UK.
It is useful to treat this as a broad optimum rather than a precise target. Solar output does not suddenly collapse when a panel moves a few degrees away from the theoretical best angle.
A roof at 25°, 30°, 40° or 45° can all support a productive solar installation. The system’s direction, shading and installed capacity may make a greater difference than the variation between these pitches.
Solar-panel pitch at a glance
| Panel pitch | General UK assessment | Main consideration |
|---|---|---|
| Nearly flat | Can be usable with an appropriate design | Drainage, dirt and mounting system |
| 10–20° | Common on space-constrained flat roofs | Lower tilt can allow more panels |
| 20–30° | Good | Usually not worth altering |
| 30–40° | Excellent annual benchmark | Strong year-round compromise |
| 40–50° | Still very suitable | Direction becomes more important |
| Above 50° | Potentially suitable | Seasonal and orientation effects increase |
| Vertical | Specialist application | Lower conventional annual rooftop output |
Do solar panels need to be installed at exactly 35°?
No. Although 35° is often quoted as the ideal UK solar-panel angle, it is not a pass-or-fail threshold.
The difference between two nearby angles is generally gradual. A homeowner with a suitable 30° roof should not assume that the panels need to be raised to 35°. The additional frame, wind loading, visual impact and installation cost could outweigh the relatively small generation improvement.
For a normal pitched-roof installation, the sensible approach is usually to:
- Measure the roof’s actual pitch.
- Model the system at that pitch.
- Account for direction and shading.
- Compare the predicted annual generation with the household’s electricity needs.
- Install the panels at the existing roof angle unless there is a clear reason not to.
The theoretical optimum becomes more relevant when the installer can choose the angle freely, such as on a flat roof or ground-mounted system.
Should you change the panel angle?
- Conventional pitched roof
- Usually not. The panels will normally follow the existing roof plane.
- Flat roof
- Possibly. The angle forms part of the complete layout design.
- Ground-mounted array
- The installer can normally select an angle to suit annual or seasonal objectives.
- Existing solar system
- Ask how much additional generation a change would deliver before paying to alter the mounting arrangement.
How do roof pitch and direction work together?
Pitch should not be considered separately from the direction the roof faces.
A tilted panel receives the most direct sunlight when its surface points towards the sun. Changing the pitch can therefore help or hinder performance depending on the direction of the roof.
| Roof direction | How pitch affects the decision |
|---|---|
| South | A moderate pitch provides strong alignment with the midday sun |
| South-east or south-west | Remains effective across a wide range of normal roof pitches |
| East or west | Produces more in the morning or afternoon; steeper pitches require careful modelling |
| North-east or north-west | Performance becomes more sensitive as the roof gets steeper |
| North | A steep pitch points the panels more decisively away from the strongest sunlight |
This is why a shallow north-facing roof and a steep north-facing roof should not receive the same generation assumption.
An unshaded east- or west-facing roof may also be more useful than a theoretically ideal south-facing roof affected by significant shade.
For a detailed comparison, see Solar Panel Direction: South, East, West and North Compared.
Is a shallow roof suitable for solar panels?
A shallow roof can still be suitable for solar PV. It may perform particularly well during summer, when the sun travels higher across the sky.
Possible advantages include:
- Good exposure to high summer sunlight
- A low visual profile
- Less severe performance penalties on some roofs facing away from south
- The possibility of fitting a compact array
However, shallow installations need additional consideration.
Rainwater runs more slowly from panels installed at a low angle. Dirt, leaves and other debris may therefore be more likely to remain around the lower edge. The roof’s drainage routes must also remain unobstructed.
There is no universal minimum pitch that applies to every solar panel. The permitted angle can depend on the panel manufacturer, mounting system and roof design. The installer should confirm that the proposed inclination complies with the relevant installation instructions.
A shallow roof must also be checked for:
- Standing water
- Waterproofing condition
- Nearby parapets
- Chimney or building shadows
- Leaf accumulation
- Maintenance access
- Manufacturer requirements
A shallow pitch on its own is not a reason to reject the roof.
Is a steep roof suitable for solar panels?
A steep roof can also support a productive solar array, particularly when it faces south, south-east or south-west.
Steeper panels are better aligned with the lower sun during parts of autumn and winter. Their production can therefore be distributed slightly differently across the year compared with a shallow array.
That does not mean a steep roof will produce large amounts of winter electricity. UK winter days are shorter and contain much less available solar energy. Pitch can improve the panel’s alignment, but it cannot overcome the seasonal reduction in daylight.
The direction of a steep roof is especially important. A steep south-facing roof may perform well, while a steep north-facing roof points the panels farther away from the strongest part of the sky.
Other practical considerations include:
- More difficult installer access
- Scaffolding requirements
- Roof-covering condition
- Wind exposure
- Safe mounting and fixing
- Space around ridges and roof edges
The installer’s forecast should use the actual measured pitch rather than a standard assumption.
What is the best solar-panel angle for a flat roof?
There is no single best flat-roof angle.
A tilt of approximately 30–40° may maximise the annual generation of an individual south-facing panel. But using that angle across a flat roof can create long shadows behind each row.
The rows then need to be spaced farther apart, reducing the number of panels that fit.
A lower angle may produce slightly less electricity per panel but allow a greater total capacity to be installed. The complete system could consequently generate more electricity from the available roof.
Flat-roof design must balance:
- Output from each panel
- Row-to-row shading
- Total panel capacity
- Wind loading
- Ballast or fixing requirements
- Drainage and waterproofing
- Maintenance access
- Planning constraints
South-facing tilted rows
One option is to arrange the panels in rows facing south.
This can deliver strong annual generation from each panel, but every row casts a shadow behind it. The higher the angle, the farther that shadow can extend when the sun is low.
Adequate spacing is therefore needed between rows. If the roof is small, this can leave large areas unused.
A south-facing layout may suit a large, open roof where there is sufficient room to provide the required separation.
Low-angle east–west layout
A second option is to arrange panels back-to-back, with one side facing east and the other west.
These panels are normally installed at a relatively shallow angle. This can create a compact layout with less unused space between rows.
An east–west system may:
- Fit more panels on the roof
- Produce earlier in the morning and later in the afternoon
- Create a broader daily generation profile
- Reduce the peak around midday
- Have a lower visual profile
- Reduce wind exposure compared with steeper frames
Each panel may generate less than an optimally tilted south-facing panel, but the larger installed capacity can sometimes produce more electricity from the roof as a whole.
| Consideration | South-facing rows | Low-angle east–west |
|---|---|---|
| Output from each panel | Usually higher | Usually lower |
| Number of panels | Can be limited by row spacing | More may fit |
| Daily generation | Concentrated around midday | Spread across more of the day |
| Row shading | Requires careful separation | Reduced with a suitable layout |
| Wind exposure | Can increase with steeper frames | Often lower at shallow angles |
| Best suited to | Large roof with sufficient space | Space-constrained flat roof |
The correct decision must be based on a layout and generation model rather than a generic angle.
See South vs East–West Solar Panel Layouts on Flat Roofs for a more detailed comparison.
How does pitch change summer and winter generation?
The sun follows a higher path across the sky during summer and remains much lower during winter.
As a result:
- Shallower panels tend to favour higher summer sunlight.
- Steeper panels are better aligned with lower autumn and winter sunlight.
- A moderate pitch provides a compromise for annual generation.
- The angle that maximises annual output may not maximise winter output.
Most fixed domestic arrays are designed around annual generation because adjusting the panels seasonally would add cost and complexity.
There can still be reasons to consider the production profile.
A household with high summer electricity use may be well matched to a shallow array. A home with a heat pump may value additional production during spring and autumn. An east–west layout may suit a household that uses more electricity during the morning and early evening.
A home battery can move solar electricity from the middle of the day into the evening, but it cannot store summer production for use in winter.
Is it worth changing the panel angle?
On an existing pitched roof, it is rarely worth adding a special frame simply to move the panels closer to the theoretical optimum.
Changing the angle can introduce:
- Additional equipment and labour
- Greater wind loading
- More complex structural requirements
- Increased projection above the roof
- Additional shading between rows
- Greater visual impact
- Possible planning complications
It is usually better to install the panels at the existing roof angle and assess their expected output accurately.
Changing or selecting the angle is more relevant when:
- The installation is on a flat roof
- The panels will be ground mounted
- The supporting surface is nearly horizontal
- A different angle would avoid significant shading
- The system has a specific seasonal objective
- Several layouts are being compared on a large roof
Ask the installer to provide generation estimates for both arrangements. A claimed improvement should be expressed in annual kilowatt-hours, not simply described as “more efficient”.
How can you find your roof pitch?
Important
You only need an approximate pitch during the early research stage. The installer should take or confirm the final measurement during the property survey.
Safe ways to find the angle include checking architectural or extension plans, looking at information from an earlier roof survey, using an angle finder against an accessible rafter inside the loft, using a phone inclinometer for an approximate reading, or asking a roofer or solar installer to measure it.
Do not climb onto the roof simply to obtain this measurement.
If the roof’s rise and horizontal run are known, the pitch can be calculated using:
Pitch in degrees = arctan(rise ÷ run)
An approximate phone or loft measurement is adequate for comparing broad options. The final design should use the installer’s confirmed figure.
What should the installer include in the generation forecast?
A solar quotation should not rely on the statement that your roof has a “good angle”. It should show how the actual roof has been included in the calculation.
Look for:
- Panel inclination in degrees from horizontal
- Direction of each array
- Installed capacity in kilowatt-peak
- Predicted annual generation in kilowatt-hours
- Shading assumptions
- Separate calculations for differently facing roof sections
- Relevant system losses
- Flat-roof row spacing
- Parapet and roof-obstruction shading
- Proposed mounting method
- Structural or ballast requirements
MCS installers are expected to establish the array’s inclination, orientation and shading when preparing a performance estimate.
If the quotation uses an assumed pitch, ask the installer to confirm it during the survey. If the final layout differs from the original assumptions, the generation estimate should be updated.
What matters more than a small difference in pitch?
Homeowners can spend too much time trying to identify the perfect angle. Several other factors can have a greater influence on the result.
Shading
Trees, chimneys, dormers and nearby buildings can block direct sunlight. A shaded south-facing roof may produce less than an unshaded east- or west-facing roof.
Available roof area
The system with the best angle is not necessarily the system with the highest output. A larger array on a slightly less favourable roof plane may generate more electricity overall.
Roof direction
Direction influences both annual output and the time of day when electricity is generated. It must always be considered alongside pitch.
Roof condition
The roof should be in a condition that is likely to outlast the solar installation. Completing necessary roof repairs before fitting the panels is normally easier than removing and reinstalling the array later.
Structural suitability
The structure must support the panels and mounting equipment. Flat-roof systems may also require significant ballast unless they are mechanically fixed.
Household consumption
Maximum annual generation is useful, but so is producing electricity when the household can use it. Work patterns, EV charging, battery storage and heat-pump operation can affect which layout provides the greatest practical value.
Planning, wind and roof constraints
Raising panels away from the roof surface changes more than their exposure to sunlight.
A steeper frame can increase:
- Wind uplift
- Ballast requirements
- Loads on the roof structure
- Projection above the roof
- Visual impact
- Shadows cast over adjacent rows
Mechanically fixed systems must preserve the roof’s waterproofing. Ballasted systems must remain secure without exceeding the roof’s load capacity. Existing roof warranties should also be checked before the covering is penetrated or loaded.
Planning rules vary across England, Scotland, Wales and Northern Ireland. Additional restrictions may apply to listed buildings, conservation areas and unusual installations.
An installation being permitted development does not mean it is structurally suitable. Planning, structural safety and electrical compliance are separate considerations.
Which pitch is right for your roof?
| Your situation | Likely starting point |
|---|---|
| South-facing roof at 30–40° | Excellent conventional installation |
| South-facing roof at 20–30° | Normally install at the existing pitch |
| South-facing roof at 40–50° | Still highly suitable |
| East- or west-facing roof | Model the actual pitch and generation timing |
| Shallow north-facing roof | Obtain a site-specific forecast |
| Steep north-facing roof | Compare carefully with other roof planes |
| Small flat roof | Consider a compact low-angle layout |
| Large unshaded flat roof | Compare south-facing and east–west layouts |
| Ground-mounted array | Select the angle around the system's objectives |
The best decision is based on the complete roof rather than one measurement.
Frequently asked questions
What is the ideal roof pitch for solar panels in the UK?
Approximately 30–40° from horizontal is a strong year-round benchmark, particularly for a south-facing array. Other angles can still produce worthwhile results.
Is a 20° roof too shallow for solar panels?
No. A 20° roof can support a productive solar installation. Drainage, dirt accumulation, shading and the panel manufacturer’s installation requirements should still be checked.
Is a 45° roof too steep for solar panels?
No. A 45° roof can be highly suitable, especially when it faces south, south-east or south-west.
Can solar panels be installed completely flat?
Some systems can be installed at very low inclinations, but completely flat panels require careful consideration of drainage, dirt, waterproofing and manufacturer requirements. A small tilt is commonly incorporated into flat-roof designs.
Should panels be tilted differently from the pitched roof?
Usually not. Panels on a conventional pitched roof normally follow the existing roof angle. Changing that angle requires additional framing and may provide only a modest generation improvement.
What angle should solar panels use on a flat roof?
There is no universal answer. The installer should compare individual panel output, row shading, total panel capacity, wind exposure and structural requirements.
Do steeper panels produce more electricity in winter?
A steeper angle can improve alignment with the lower winter sun. It cannot compensate for the UK’s shorter winter days and lower overall solar availability.
Does pitch matter more than direction?
Pitch and direction interact, but direction, shading and available roof area can matter more than a small difference around the optimum angle.
Can I measure the roof pitch myself?
You can obtain an approximate measurement from inside an accessible loft using an angle finder or phone inclinometer. The installer should confirm the pitch during the site survey.
The best angle is the one that works for the complete roof
A pitch of approximately 30–40° is an excellent UK benchmark, but it should not be treated as a requirement.
On a conventional pitched roof, the most practical approach is usually to use the existing angle and model the expected generation accurately. On a flat roof, the installer should compare complete layouts rather than trying to optimise one panel in isolation.
Before accepting a proposal, make sure the estimate includes the actual pitch, direction, shading and proposed layout.
Is your roof suitable for solar panels?
Roof pitch is only one part of the assessment. Check the roof’s direction, shading, usable area, condition and structural suitability before deciding how large your solar system should be.