If you are choosing solar shading analysis software for UK work in 2026, the selection problem is different from every other market on this site. In Britain a shading study is not a courtesy you extend to a cautious customer. It is a numbered input to a certification calculation. MCS requires domestic performance estimates to be produced with the Standard Estimation Method, and that method multiplies a location and orientation yield figure by an explicit shade factor. Get the shade factor wrong, or fail to record how you derived it, and you have an audit finding rather than a rounding error. On top of that, the physics is unusually unforgiving: at 51.5 degrees north the December sun tops out near 15 degrees, so near-object shadows in winter are three to four times longer than the same obstruction throws in Arizona. This guide ranks the ten tools UK designers genuinely use for shading, priced in pounds, starting with SurgePV at roughly £1,030 per user per year and naming exactly where it loses.
Direct answer. The best solar shading analysis software for the UK in 2026 is SurgePV, at about £1,030 per user per year on the 5-User Team plan, because it runs an 8,760-hour module-level simulation with a Perez-style anisotropic sky model and exports a horizon profile you can defend to an MCS assessor. It does not print the MCS shade factor in the MCS format, so most certified installers pair it with Easy PV, which is free and does. For lender due diligence on commercial roofs, PVsyst at CHF 700 per user per year, roughly £620, still wins outright, and it is cheaper per seat than we are.
This guide is written for MCS certified installers, EPC design teams and independent engineers whose yield numbers are being challenged. If you want the physics without the UK regulation, read the global pillar on solar shading analysis software first. For the wider tool decision, our solar design software UK ranking covers the full workflow.
Why the MCS Shading Factor Changes the Tool Decision
Everywhere else, shading analysis competes with a spreadsheet for the designer’s attention. In Britain it competes with nothing, because the estimate you hand the customer has a defined shape.
The MCS Standard Estimation Method, published as MCS guidance alongside the PV installation standard MIS 3002, produces the annual figure roughly as:
Annual kWh = installed kWp × Kk × SF
Kk is a lookup value that depends on the site’s postcode zone, the array’s orientation and its tilt. It is a table, and no software gets credit for reading a table correctly. SF is the shade factor, and that is the number your tool has to earn. It is a dimensionless multiplier at or below 1.0 that represents the proportion of the unshaded resource the array will actually see.
Two properties of SF decide which tool you buy:
- It has to be derived, not asserted. The method expects a horizon or obstruction assessment taken from the array position, translated onto a sun path diagram for the site latitude, and reduced to a factor. An assessor can ask what you measured, from where, and on what date.
- It has to appear on the customer’s document. A performance estimate that shows only “3,650 kWh per year” with no method reference and no stated shade factor is an incomplete estimate regardless of how good the simulation behind it was.
That second point is where expensive global software quietly fails. A tool can run a physically superior 8,760-hour simulation and still leave you non-compliant, because it reports a percentage energy loss rather than an MCS shade factor on an MCS-shaped document. Percentage loss and shade factor are related but they are not the same number, and substituting one for the other in a customer estimate is the single most common MCS documentation error we see when we audit UK partner design packs.
📘 Regulation note
Per MCS, a domestic PV performance estimate must be produced using the Standard Estimation Method with a stated shade factor and the assumptions recorded. MCS revises its guidance documents periodically, so confirm the current version and the current shading procedure on the MCS site before you lock a proposal template. Access to the Smart Export Guarantee depends on that MCS certification remaining clean.
Bring one of your own sites to a free SurgePV demo. We will build the 3D roof from a satellite address, run the 8,760-hour shading simulation, and hand you the SLD, BOQ and branded proposal on the call.
Book a free SurgePV demo → Compare pricingWhat 51.5 Degrees North Does to Shadow Length
This is the arithmetic every imported rule of thumb gets wrong, and it is worth doing on paper once so you never trust a US spacing table again.
Solar noon elevation on the winter solstice is approximately 90 minus latitude minus 23.44. For London at 51.5N that is 15.1 degrees. The shadow a vertical obstruction casts is its height divided by the tangent of the sun elevation, so the multiplier is 1 / tan(15.1) = 3.7.
Run that against real obstructions and the numbers stop being abstract.
| Obstruction | Height | Midwinter noon shadow, London (51.5N) | Same obstruction, Phoenix (33.4N) |
|---|---|---|---|
| Parapet wall | 1.2 m | 4.4 m | 1.8 m |
| Chimney stack | 3.0 m | 11.1 m | 4.6 m |
| Two-storey neighbouring gable | 8.0 m | 29.6 m | 12.2 m |
| Mature tree | 12.0 m | 44.4 m | 18.3 m |
Phoenix is at 33.4N, so its December noon elevation is about 33.2 degrees and its multiplier is 1.53. The same chimney that costs an Arizona designer four and a half metres of roof costs a London designer eleven. Any spacing heuristic, any “keep obstructions at twice their height away” rule, and any default obstruction buffer in a tool configured for the American market is wrong here by a factor of two or more.
The 9am to 3pm rule does not survive the journey. American shading practice often targets a shade-free window from 9am to 3pm on the winter solstice. In London on 21 December the sun is at roughly 5.3 degrees three hours either side of solar noon, giving a shadow multiplier near 10.7. A 3 metre chimney throws a 32 metre shadow at that moment. No British urban roof clears that, and no honest tool pretends otherwise. UK practice narrows to a shorter window around noon and accepts a quantified winter loss instead, which is precisely why the shade factor exists as a number rather than as a pass or fail gate.
Inter-row spacing on flat UK roofs. Take a 2.28 m module in portrait at 20 degrees tilt on a flat commercial roof. The vertical rise is 2.28 × sin(20) = 0.78 m. To clear the row behind at midwinter noon in London you need 0.78 × 3.7 = 2.9 m of shadow clearance plus the module’s own horizontal projection of 2.28 × cos(20) = 2.14 m, so a pitch near 5.0 m and a ground coverage ratio around 0.45. The same array in Phoenix needs a pitch of about 3.3 m for a GCR near 0.68. That difference is roughly a third of your usable roof, and it is the reason UK flat-roof designs trend toward 10 degree east-west ballasted systems rather than steep south-facing rows.
Get your sizing sanity-checked. For a fast second opinion on array size, spacing and winter shading loss before you commit to a layout, run the numbers through our free solar calculator or talk to our engineering team.
Why a British Sky Punishes an Isotropic Model
The second country-specific criterion is less visible than shadow geometry and costs more money.
Across most of the UK, well over half of annual plane-of-array irradiance arrives as diffuse radiation scattered by cloud and atmosphere rather than as direct beam. The JRC PVGIS dataset shows this clearly for any British postcode you care to check. That changes what an obstruction actually does. A chimney at 51.5N is not mainly blocking a sunbeam. It is removing a wedge of the sky dome from the module’s view for the entire year, including every overcast hour when there is no beam to block at all.
Sky models handle that removal very differently:
| Sky model | How it treats the sky dome | Effect on a partly shaded UK roof |
|---|---|---|
| Isotropic (Liu and Jordan) | Uniform brightness in all directions | Understates loss near the horizon band, overstates it near the zenith |
| Hay and Davies | Splits circumsolar from isotropic background | Better, still thin on horizon brightening |
| Perez | Circumsolar, horizon brightening and isotropic background modelled separately | Closest match to measured maritime data |
| Beam-only geometry (common in sales tools) | Shadow polygons only, no diffuse view factor | Systematically wrong on any obstructed British roof |
The practical test to run on any tool you are evaluating: model the same Manchester terrace twice, once with a 3 metre chimney and once without, and see whether the tool applies a sky view factor to the modules the chimney overlooks or only subtracts beam hours. If the annual loss the tool reports scales with sunny-hour geometry alone, it is missing the majority of the resource. On our own audits the gap between a beam-only estimate and a Perez-based estimate on the same shaded UK roof routinely runs two to four percent of annual yield, in both directions depending on obstruction position. That is larger than the difference between most of the modules on your shortlist. Our diffuse horizontal irradiance and shading loss glossary entries set out the underlying definitions.
The 5-Point MCS Shading Readiness Test
This is the framework we use before putting any shading tool in front of a UK design team. Score each axis 1 to 10, out of 50. Nothing below 38 goes into an MCS certified workflow.
- Shade factor output. Does it produce a number in the shape the Standard Estimation Method wants, on a document the customer keeps, with the derivation recorded?
- Horizon capture and import. Can it take a measured horizon profile, from a handset, a photograph or a
.horfile, rather than only inferring obstructions from satellite imagery? - Sky model quality. Perez or equivalent anisotropic transposition, with a genuine sky view factor applied to partial obstructions.
- Winter geometry honesty. Does it show the low-sun hours explicitly, ideally as a monthly or hourly heat map, rather than burying midwinter inside an annual average?
- Evidence quality for an assessor. Sun path diagram, obstruction schedule, capture date and position, exportable as a PDF that goes into the handover pack.
Scores across the ten tools below: SurgePV 43, PVsyst 42, Easy PV 40, HelioScope 38, PV*SOL premium 40, Aurora Solar 33, Solmetric SunEye 39, Solar Pathfinder 34, Scanifly 33, horizon-import workflows 35. The scoring is ours and it is opinionated. SurgePV and PVsyst sitting one point apart, with a free tool a further two points back, is the honest result.
Top 10 Solar Shading Analysis Tools in the UK Compared
Pricing is each vendor’s own published 2026 list price in the currency they bill in. Where a pound figure converts a dollar price the rate used is approximately £0.79 per US dollar. Hardware is one-off capital, shown separately.
| # | Tool | Published price | Shading capability | Best for |
|---|---|---|---|---|
| 1 | SurgePV | US$1,299/user/yr (about £1,030) | 8,760-hr module-level, Perez sky, horizon export, annual heat map | Certified installers doing 5+ UK jobs a month |
| 2 | PVsyst | CHF 700/user/yr, Professional | Reference near-shading 3D scene plus horizon file import | Lender due diligence and disputed yield claims |
| 3 | Easy PV | Basic free; Pro £35/month | MCS Standard Estimation Method shade factor output | Any MCS certified domestic installer |
| 4 | HelioScope | Basic US$159/mo (US$1,620/yr); Pro US$259/mo (US$2,640/yr) | Module-level 8,760-hr on C&I roofs, clean loss tree | Commercial rooftop consultancies |
| 5 | PV*SOL premium | EUR 845/named user/yr + VAT | Animated 3D shading walkthrough, strong visual output | Engineering-led firms and customer objections |
| 6 | Aurora Solar | Basic US$135/user/mo billed annually (US$159 monthly); Premium US$220 (US$259 monthly) | Good residential shade capture inside a sales workflow | Large residential shops already on Aurora |
| 7 | Solmetric SunEye 210 | US$2,195 base, North America, current product | Fisheye horizon capture at the array position | Teams needing measured evidence on site |
| 8 | Solar Pathfinder | Kit US$299 to US$349, Assistant software US$219 | Reflective dome horizon trace, no batteries | Surveyors wanting a cheap defensible record |
| 9 | Scanifly | Not publicly listed, quote only | Drone photogrammetry into a shade-capable 3D model | Complex, steep or unsafe UK roof stock |
| 10 | Horizon import workflows | PVGIS free, Meteonorm CHF 675 single licence | PVGIS or Meteonorm horizon profiles fed into a simulator | Engineers who already own a simulator |
The blunt version of that table: several of these cost less than SurgePV. PVsyst Professional is CHF 700 per user per year, about £620, so five seats are CHF 3,500 against US$6,495 for five SurgePV seats. PV*SOL Premium is EUR 845 per named user. Easy PV’s Basic tier, the one that prints the document MCS actually asks for, is free, and its Pro tier is £35 a month. We rank SurgePV first on the engine and the horizon evidence, not on price, and a domestic-only installer may well not need it at all.
The honest read: positions 1 to 5 are the working shortlist. Positions 7 and 8 are hardware that complements software rather than replacing it, and position 10 is a technique rather than a product, which is exactly why most UK teams never think to price it.
1. SurgePV
What it does best for UK shading. SurgePV builds the 3D roof from a satellite address, detects chimneys, dormers, parapets and adjacent gables, then runs an 8,760-hour module-level simulation with bypass-diode physics and a Perez-style anisotropic sky model. Three things matter specifically here. It applies a sky view factor to partial obstructions rather than treating them as beam blockers, which is the correct behaviour under a British sky. It exports a horizon profile and a sun path diagram from the array position, which is the evidence an MCS assessor wants to see behind your shade factor. And the annual shading heat map colours every module by percent irradiance loss, so a designer spots the winter-shaded northern rows in seconds rather than reading a loss table. The shadow analysis module is bundled on every paid plan rather than gated behind a tier.
Pricing. £1,030 (US$1,299) per user per year on the 5-User Team plan, so £5,150 for five seats. Individual seats run about £1,510 a year. Free trial, no credit card.
Who it suits. MCS certified installers and EPCs doing five or more UK designs a month who want the shading run, the string regrouping and the proposal in one licence.
Honest limitations. Four concrete ones, and the first is the one that matters most on this page. It does not print an MCS shade factor on an MCS-shaped Standard Estimation Method document. It gives you an accurate percentage loss and the horizon evidence, and a competent designer converts that into a compliant estimate, but the conversion is a manual step and Easy PV does it for nothing. Its horizon capture is satellite-derived, not measured. On a dense urban site with a poorly imaged rear elevation you still want a SunEye or a Pathfinder reading, and SurgePV will import that profile rather than generate it. Its brand carries no weight with a conservative UK funder, because it launched in 2025, so on a financed commercial roof you will still be asked for PVsyst. And the deciduous tree model is coarse: a single seasonal canopy density flag does not capture the difference between a bare December oak and a leafed July one as well as a hand-built PVsyst scene with two shading objects does.
Book a SurgePV demo and bring a genuinely awkward UK roof, ideally a terrace with a rear chimney, so you can judge the sky view factor behaviour rather than a showcase file.
2. PVsyst
What it does best. PVsyst remains the reference for near-shading. Its 3D shading scene lets you build obstructions to real dimensions, its horizon file import accepts profiles from PVGIS, Meteonorm and most survey handsets, and its loss diagram separates near shading from horizon shading from electrical mismatch, which is precisely the breakdown an independent technical adviser wants when a yield claim is disputed. On sky modelling it is the strongest tool on this list, which matters more in Britain than in Spain.
Pricing. CHF 700 per user per year for the Professional edition, about £620, sold as an annual subscription rather than a perpetual licence. Education is CHF 420 and group discounts run 5 to 20 percent by quantity. It is cheaper per seat than SurgePV, and we are not going to pretend otherwise.
Who it suits. Independent engineers, technical due diligence teams, and anyone whose shading number is going to be argued about in front of a lender.
Honest limitations. Windows desktop only, a steep learning curve, and building a shading scene by hand takes an hour on a roof SurgePV models in a minute. It has no MCS output whatsoever, no proposal generation and no customer-facing visual. Our PVsyst alternative guide covers where the tradeoff sits for a working installer.
3. Easy PV
What it does best. Easy PV, built in Cambridge by Midsummer Energy, is the only tool on this list whose primary output is the thing MCS actually asks for. It produces the Standard Estimation Method calculation with an explicit shade factor, in the format a certification body expects, and it does it free. For a domestic installer whose shading problem is fundamentally a documentation problem rather than a physics problem, it removes the entire compliance risk for zero pounds.
Pricing. The Basic tier is free, which is the tier that produces the Standard Estimation Method output. Pro is £35 a month and Enterprise pricing is not publicly listed. Midsummer also monetises through component sales.
Who it suits. Every MCS certified domestic installer in Britain, including those who run something else for the engineering.
Honest limitations. The shading engine underneath is not an 8,760-hour module-level simulation and does not claim to be. There is no bankable P90 output, no per-module heat map, no bypass-diode modelling and no meaningful commercial or ground-mount capability. It answers the certification question well and the engineering question shallowly, so on a 400 kW warehouse roof it is the wrong tool.
4. HelioScope
What it does best. Module-level 8,760-hour simulation with a loss tree that UK independent engineers read without argument. On a Midlands distribution shed with rooftop plant, ducting and a parapet, HelioScope quantifies the mismatch losses from partial shade properly rather than averaging them away.
Pricing. Basic is US$159 a month, US$1,620 a year, for one user and 10 projects a month with a 1.25 MW DC design cap. Pro is US$259 a month, US$2,640 a year, with a 5 MW cap. Five Basic seats come to about US$8,100, roughly £6,400.
Who it suits. Commercial and industrial consultancies whose deliverable is a yield report.
Honest limitations. No MCS shade factor, no horizon handset import worth the name, no satellite roof capture and weak proposal tooling that forces a second licence. Read our HelioScope alternative comparison before committing seats.
5. PV*SOL premium
What it does best. The animated 3D shading walkthrough is the most persuasive customer-facing shading artefact any tool produces. When a homeowner in Surrey insists the neighbour’s sycamore is not a problem, playing the winter shadow sweep across their own roof ends the conversation in ninety seconds. The underlying simulation is trusted and the European component database is deep.
Pricing. EUR 845 per named user per year plus VAT for PVSOL Premium, with standard PVSOL at EUR 585. There is no perpetual licence variant on sale any more: Valentin Software stopped selling them on 19 November 2024 and maintenance renewals on existing perpetual licences ended on 1 October 2024, although those licences still run. At EUR 845 a seat it is cheaper than SurgePV.
Who it suits. Engineering-led UK consultancies and any team that loses jobs to shading disputes.
Honest limitations. Windows desktop, no MCS Standard Estimation Method output, no collaborative workflow, and every job starts with manual 3D modelling because there is no satellite capture. Our PV*SOL alternative writeup has the detail.
6. Aurora Solar
What it does best. Aurora’s shade capture inside a residential sales workflow is genuinely good, with mature roof plane detection that copes with UK suburban housing stock and irradiance maps that present well to a homeowner.
Pricing. Basic is US$135 per user per month billed annually, US$159 billed monthly. Premium is US$220 annually, US$259 monthly. Enterprise is quoted, plan sets are a separately priced service rather than a plan inclusion, and site models start at US$9.99.
Who it suits. Large residential installers already running Aurora who do not want a second tool.
Honest limitations. The UK regulatory layer is thin. No MCS shade factor, no Standard Estimation Method document, and the LIDAR modelling and bankable shade reports sit on Premium rather than Basic, with plan sets billed as a separate service on top. See our Aurora Solar alternative comparison.
7. Solmetric SunEye 210
What it does best. A fisheye camera handset held at the array position that captures the actual horizon and overlays the sun path, returning monthly and annual solar access percentages. It is measured evidence rather than modelled inference, and that distinction is worth a great deal when an assessor asks how you derived a shade factor on a site where satellite imagery is poor.
Pricing. US$2,195 base for North America, roughly £1,730, and that includes a lifetime PV Designer licence. Contrary to a widely repeated claim, the 210 has not been wound down: Solmetric has been a Fluke company since the acquisition announced in September 2023 and still sells it new. As of 2 August 2026 it is out of stock with a stated 10 to 12 week lead time, so a UK team should order well ahead and budget for import on top.
Who it suits. Survey teams doing volume domestic work in dense urban terraces.
Honest limitations. The 10 to 12 week lead time plus UK import is the headline planning risk. Beyond that it is a capture device: it gives you solar access percentages, not module-level energy, so it feeds a simulator rather than replacing one. Readings are also position-sensitive, and a reading taken from the scaffold rather than the array plane is not the reading you think you took.
8. Solar Pathfinder
What it does best. A reflective transparent dome over a sun path diagram, traced by hand. No battery, no firmware, no software licence required to take the reading. On a wet Yorkshire roof in February it works when a handset has gone flat, and the resulting trace is a physical record with a date on it.
Pricing. Solar Pathfinder bills in US dollars and publishes its prices: the kit is US$299 to US$349 depending on configuration and the Assistant software is US$219, with 5 percent off when an instrument and a software package are bought together. That is roughly £425 for one complete kit at US$1 to £0.79, approximate and rate-dependent.
Who it suits. Surveyors who want a cheap, durable and defensible horizon record.
Honest limitations. Manual tracing introduces operator error, it is slow across a multi-plane roof, and it produces a horizon profile rather than an energy figure. You are still buying a simulator afterwards. Reading a low-contrast winter horizon through the dome on an overcast day is also harder than the marketing photographs suggest.
9. Scanifly
What it does best. Drone photogrammetry converts a flight into an as-built 3D site model with real obstruction geometry, which then drives a shading calculation. On a steep slate roof, a listed building or a multi-dormer terrace where sending a surveyor up is the wrong call, this is a safety gain as well as an accuracy gain.
Pricing. Scanifly does not publish a price list. Pricing is quoted and scales with team size and capture volume.
Who it suits. Installers with complex UK roof stock and an existing drone programme.
Honest limitations. It is capture first and simulation second, so a bankable yield report still comes from elsewhere. UK weather and CAA operational rules cut usable flying days well below what the vendor’s US material implies, and it produces no MCS output. Our Scanifly alternative writeup covers the cheaper routes.
10. Horizon Import Workflows
What it does best. This is a technique, not a product, and it is the most under-used capability in the UK. PVGIS publishes a horizon profile for any coordinate in Europe derived from terrain data, downloadable as a .hor or CSV file. Meteonorm sells a richer version. Both import directly into PVsyst, and most serious simulators accept the same format. For a rural site in a Welsh valley or a Pennine hillside, terrain horizon shading can cost several percent of annual yield and no satellite roof model will ever see it, because the obstruction is a mountain three kilometres away.
Pricing. PVGIS horizon data is free. Meteonorm bills in Swiss francs and publishes CHF 675 for a single perpetual licence, CHF 350 for each additional licence (about £600 at CHF 1 to £0.89, approximate and rate-dependent).
Who it suits. Any engineer who already owns a simulator and works outside flat urban England.
Honest limitations. Terrain horizon data does not know about buildings, trees or anything else built by humans, so it complements a near-shading model rather than replacing one. Resolution is coarse on short-range obstructions, and combining a terrain horizon with a near-shading scene without double-counting the overlap requires care.
Send us a disputed roof. If a customer or a funder is challenging your yield figure, send us the design and our engineers will return an independent shading and yield opinion within 48 hours. Request a review →
Pricing in Pounds for a Five-Person UK Team
| Tool | Per seat | Five seats per year | What you get for shading |
|---|---|---|---|
| SurgePV | US$1,299/user/yr (about £1,030) | US$6,495 (about £5,150) | 8,760-hr module-level, Perez sky, heat map, horizon export, plus full design and proposals |
| Easy PV | Basic free, Pro £35/mo | £0 on Basic | MCS shade factor and Standard Estimation Method document |
| Horizon import (PVGIS) | Free | £0 | Terrain horizon profile for any UK coordinate |
| Solar Pathfinder | US$540 one-off, about £425 | US$1,080 for two kits, about £850 | Manual horizon trace, no licence |
| PVsyst | CHF 700/user/yr (about £620) | CHF 3,500 (about £3,100) | Reference near-shading scene and loss diagram |
| HelioScope | US$1,620/yr Basic | US$8,100 (about £6,400) | C&I module-level simulation |
| PV*SOL premium | EUR 845/named user/yr + VAT | EUR 4,225 | 3D animated shading walkthrough |
| Solmetric SunEye 210 | US$2,195 base | US$4,390 for two units (about £3,470) | Measured fisheye solar access |
| Scanifly | Not publicly listed | Quote only | Drone capture into 3D shade model |
| Aurora Solar | US$1,620/yr Basic, US$2,640 Premium | US$8,100 to US$13,200 (about £6,400 to £10,430) | Residential shade inside a sales workflow |
Note what that table says about us: five PVsyst seats cost roughly half what five SurgePV seats cost, and the tool that produces the MCS document is free. The comparison most UK installers should run is not SurgePV against PVsyst on price, because we lose that. It is SurgePV plus free Easy PV plus one shared Pathfinder at roughly £5,600 a year against a stack of Aurora Premium for design plus HelioScope for commercial plus a manual MCS spreadsheet, which lands near £17,000 with three logins and a compliance gap. If you are a two-person domestic outfit doing eight installs a quarter, Easy PV alone plus a Pathfinder kit at about £425 is a complete and compliant answer, and we would tell you that on a call.
Mistakes UK Designers Make on Shading
-
1
Reporting a percentage loss where the estimate needs a shade factor. They are different numbers on different documents. Substituting one for the other is the most common MCS documentation finding we see on partner design packs.
-
2
Importing an American obstruction buffer. A rule built for 33N understates British midwinter shadows by a factor of about 2.4. Every default spacing value in a US-configured tool needs re-deriving at 51.5N.
-
3
Using a beam-only shading model on an obstructed roof. Over half the annual British resource is diffuse. A chimney removes sky dome, not just sunbeams, and a tool without a sky view factor misprices that in both directions.
-
4
Ignoring terrain horizon on rural sites. A satellite roof model cannot see a hill three kilometres west. Import the free PVGIS horizon profile before quoting anything in a valley.
-
5
Taking the horizon reading from the wrong position. A SunEye reading from scaffolding two metres below the array plane, or from the ridge rather than the eaves, describes a roof you are not building.
The wider set of workflow errors is covered in our writeup on common mistakes EPC companies make in rooftop solar.
⚠️ Watch out
Do not average away midwinter. An annual shading loss of 4 percent can hide a December loss of 30 percent on the same array, and a customer on a time-of-export tariff notices the seasonal shape, not the annual mean. Ask your tool for a monthly shading breakdown before you sign off any UK roof with a chimney on it.
Should a UK Team Standardise on SurgePV for Shading?
- ✓ You need shading, string regrouping and the proposal in one licence
- ✓ You bid commercial roofs alongside domestic
- ✓ You want a per-module annual heat map a customer can read
- ✓ You are happy to pair it with free Easy PV for the MCS document
- ✗ Your deliverable is lender due diligence (PVsyst)
- ✗ You are domestic-only under three installs a month (Easy PV, free)
- ✗ Your problem is winning shading arguments in a kitchen (PV*SOL)
- ✗ Your roofs cannot be safely surveyed (Scanifly first)
Verdict. For a five-person MCS certified UK installer, SurgePV plus free Easy PV is the strongest shading stack in pounds, because it pairs a genuinely anisotropic 8,760-hour engine with the one document your certification body will sample. For a disputed commercial yield figure, keep PVsyst. For a two-person domestic outfit, Easy PV and a Solar Pathfinder cost under £400 and are complete.
How Heaven Green Energy and SurgePV Help UK Teams
Heaven Green Energy has delivered more than 10,000 solar installations, and our engineering group builds the software we use ourselves. SurgePV came out of that: a design suite written by people who had to defend a yield figure to a customer six months after handover. For UK teams the entry points are:
- Shadow analysis for 8,760-hour module-level shading with an exportable horizon profile and sun path diagram.
- Heaven Designs PVsyst resource centre when the deliverable is a lender-grade loss diagram rather than a proposal.
- Rooftop detailed engineering design for full drawing packages produced by a dedicated team.
- Dual MPPT versus single MPPT for the inverter side of a shading-driven string regrouping decision.
For the wider UK tool decision see our solar design software UK ranking, the best solar proposal software UK guide and the full UK software stack. Market context sits with the IEA renewables tracker, IRENA country profiles and Solar Energy UK.
Related Shading and Design Guides
- Solar Shading Analysis Software: The Global Pillar
- Best Solar Shading Analysis Software in Ireland
- Solar Design Software UK: Top 10 Platforms Ranked
- Best Solar Proposal Software UK
- Best Solar Software UK: The Full Stack
- Best Solar Design Software in Ireland
- Solar Simulation Software Compared
- Commercial Solar Design Software Compared
Shading Analysis in Nearby Markets
The UK, Ireland and the Netherlands share the same maritime sky, though only the UK makes a shading factor a certification requirement.
- Best solar shading analysis software in the Netherlands
- Solar shading analysis software: the global guide
Frequently Asked Questions
What is the MCS shading factor and how is it calculated?
The MCS shade factor is a multiplier applied within the Standard Estimation Method, where annual output is estimated as installed kWp multiplied by a postcode, orientation and tilt lookup value, multiplied by the shade factor. The factor is derived from an obstruction or horizon assessment taken at the array position and translated onto a sun path diagram for the site. It must be stated on the customer’s performance estimate along with the assumptions behind it, not folded silently into a single kWh figure.
Is a shading study legally required in the UK?
Not by statute, but effectively yes in practice. MCS certification requires domestic performance estimates produced by the Standard Estimation Method, which includes a shade factor, and MCS certification is what gives your customer access to the Smart Export Guarantee and most finance products. So the shading study is a certification deliverable your assessor can sample rather than a legal duty. That is a stronger obligation than it sounds, because a corrective action can hold up new registrations.
How long is a winter shadow in London?
At solar noon on 21 December the sun reaches about 15.1 degrees in London, giving a shadow length of roughly 3.7 times the obstruction height. A 3 metre chimney casts an 11.1 metre shadow at the sunniest moment of that day. Three hours either side of noon the sun is near 5.3 degrees and the multiplier rises to about 10.7, so the same chimney throws a 32 metre shadow. This is why American shade-free window rules do not transfer.
Why does the sky model matter more in the UK than in Spain?
Because well over half of annual UK plane-of-array irradiance arrives as diffuse sky radiation rather than direct beam. An obstruction therefore removes a wedge of the sky dome for every hour of the year, including overcast hours with no beam at all. An isotropic model assumes uniform sky brightness and misprices that removal, particularly near the horizon. A Perez-style anisotropic model that separates circumsolar, horizon brightening and background sky matches measured British conditions far more closely.
Can I use SurgePV output for an MCS performance estimate?
You can use it as the engineering basis, but SurgePV does not print an MCS shade factor on an MCS-shaped Standard Estimation Method document. It gives you an accurate percentage loss, an exportable horizon profile and a sun path diagram, and a competent designer converts that into a compliant estimate. Most UK teams therefore run SurgePV for engineering and free Easy PV for the MCS document, which together cost the same as SurgePV alone.
Do I still need a SunEye or Solar Pathfinder if my software models shading?
Sometimes. Satellite-derived obstruction models are reliable on well-imaged suburban roofs and unreliable on dense urban terraces, rear elevations and sites with recent construction. A measured horizon reading taken at the array position is stronger evidence for an assessor and catches obstructions imagery misses. A Solar Pathfinder kit with its Assistant software costs about £425 and pays for itself the first time it prevents a disputed estimate.
What is the cheapest compliant UK shading setup?
Easy PV, which is free and produces the MCS Standard Estimation Method output with a shade factor, plus a Solar Pathfinder kit at about £425 for measured horizon evidence on awkward sites, plus the free PVGIS horizon download for rural terrain. Total capital about £425 with no annual licence. That is a genuinely complete answer for a domestic-only installer doing under three jobs a month, and it is what we would recommend on a call.
How do I model terrain shading on a rural UK site?
Download the horizon profile for the site coordinates from the JRC PVGIS tool, which derives it from terrain elevation data, then import the resulting file into your simulator. PVsyst accepts it directly and most serious tools accept the same format. This catches hillsides and valley walls that a satellite roof model cannot see, which on a Welsh or Pennine site can account for several percent of annual yield on its own.
Does SurgePV handle inter-row shading on UK flat roofs?
Yes. Set the row pitch and tilt and the engine models self-shading between rows across all 8,760 hours. The arithmetic worth checking yourself first: a 2.28 metre module at 20 degrees tilt needs roughly a 5.0 metre pitch to clear the row behind at midwinter noon in London, for a ground coverage ratio near 0.45, against about 3.3 metres and 0.68 at Phoenix latitude. Most UK flat-roof designs respond by going to shallow east-west ballast instead.
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