At a glance
| Tool | Type | Price | Best for |
|---|---|---|---|
| Ladybug Tools | Plugins for Grasshopper (Rhino), open source | Free and open source; the Grasshopper plugins need a Rhino licence | Radiation and PV studies on your own façade geometry in Rhino and Grasshopper, with full control of the model. |
| BIMsolar | Desktop app (Windows), with online services | Free plan; PRO €690 and PREMIUM €1,290 per year, excluding tax | Designing BIPV systems on an imported building model, with real or made-to-measure modules and cost results. |
| C4B | Web app, in the browser | Free plan; paid plans from €59/month (cancellation takes effect after 12 billing cycles) or €599/year, with a 7-day free trial | A first estimate at concept stage of how much electricity PV integrated in the walls could produce, façade by façade and level by level. |
| Forma Site Design | Cloud app for site planning and early environmental analysis | Standalone subscription (monthly, annual or 3-year) or included in Autodesk's AEC Collection; free trial | Seeing which façades of a massing option get the most sun in their real site context, before any panel is chosen. |
| DesignBuilder | Building energy simulation software | Annual licences per module, e.g. Simulation €850 per year (single user); free 30-day trial | Modelling BIPV as part of the building envelope in a whole-building energy simulation. |
| Solarius PV | BIM software for PV system design | Monthly, annual or multi-year subscription plans; 30-day free trial | Designing a PV system on the BIM model of a building, façades and brise-soleil included, with IFC in and out. |
| PVsyst | Desktop app (Windows) | PVsyst 8 Professional CHF 700 per year; student licence CHF 25 per year; one-month free trial | Detailed yield simulation of a PV system with a 3D scene, once the modules, strings and inverters are known. |
How to choose
Be clear about the question. At concept stage an architect wants to know whether façade PV is worth pursuing, which façades and levels to use, and how much wall is left once the glazing is in place. Later, an engineer needs a module layout, strings, inverters and a yield that will stand up to review. Tools that answer the first question quickly rarely answer the second, and the reverse is also true.
Look at how the building is described. Some tools work from a few parameters (plan, number of levels, window-to-wall ratio); others need a 3D or BIM model, imported from SketchUp, IFC or Revit, or drawn in Rhino. Façades are far more exposed to shading from neighbouring buildings than open arrays, so check whether the tool models the surroundings: Forma, Ladybug Tools, BIMsolar, Solarius PV and PVsyst work on a 3D context; a parametric estimate does not.
Check the module. Façade products range from custom glass-glass laminates and curtain-wall spandrels to standard framed modules, thin film and coloured or printed glass, and their power per square metre differs widely. See whether the tool lets you choose a typology, enter a real product or create BIPV modules, as BIMsolar's online Panel Designer does.
Read the model's assumptions. A module with an insulated back loses heat less easily than a free-standing one, and the tools that model this use a lower thermal loss factor: PVsyst's help suggests 15 W/m²K for a fully insulated back side, against 29 W/m²K for an open rack. Façades facing different ways produce very different amounts and are normally wired to separate inputs. If the PV is part of the wall's thermal performance, a building energy model such as DesignBuilder treats the BIPV as a construction of the building itself.
Ladybug Tools
Radiation and PV studies on your own façade geometry in Rhino and Grasshopper, with full control of the model.
- Ladybug radiation studies quantify the solar energy falling on your geometry, from a standard EPW weather file.
- Honeybee runs Radiance radiation studies that account for reflected light, and EnergyPlus/OpenStudio energy models.
- Honeybee's Photovoltaic Properties component turns a shade surface into a PV generator, with module type, mounting type, rated efficiency (default 15%), active area and losses as inputs.
Good to know
- The Grasshopper plugins require Rhino, Grasshopper and visual-scripting skills.
BIMsolar
Designing BIPV systems on an imported building model, with real or made-to-measure modules and cost results.
- Imports SketchUp, IFC, gbXML and IDF models, and Revit through plugins; autocladding lays BIPV modules on a surface in one click.
- Ventilated façades, curtain walls and sunshades are modelled by setting the distance between the modules and the wall; an online Panel Designer creates BIPV modules.
- The free plan includes 3D irradiation simulation; PRO adds weather generation, automatic cladding, LCOE simulation, building loads and CSV export.
- The software suite of the EU-funded PVSITES project, which simulated BIPV products together with building energy performance, was built on the BIMsolar platform.
Good to know
- Windows 7 to 11 only; macOS is not supported. PRO and PREMIUM can be tried for 14 days.
C4B
We make C4BA first estimate at concept stage of how much electricity PV integrated in the walls could produce, façade by façade and level by level.
- Each level has its own height and each façade a window-to-wall ratio; modules are laid in horizontal courses on the opaque wall left after the glazing, drawn on each façade's elevation and in a 3D view of the building.
- Five façade typologies (custom glass-glass, framed, thin film, coloured or printed, spandrel), each with a median panel from manufacturers' datasheets, about 138 to 240 Wp/m².
- Hour-by-hour simulation from the project's weather file, with monthly and annual kWh by façade and by level, and the building orientation that gives the most energy.
- Part of the Design Direction section of a project, on paid plans; the technical view, with detailed IEC, PVGIS and NREL SAM models, exact windows, extra façades, a verified product or a custom panel per façade, the inverter and editable losses, is on the Technical and Enterprise plans.
Good to know
- The base view uses a simplified calculation; the technical view refines it with more detailed models.
- No shading from neighbouring buildings, balconies or overhangs, nor between façades or levels, so lower floors in a narrow street will produce less than shown.
- Rectangular plan and vertical walls only; solar protection is a constant share of direct sun blocked; with a window-to-wall ratio the glazing is one centred strip per level, which exact windows in the technical view replace.
Forma Site Design
Seeing which façades of a massing option get the most sun in their real site context, before any panel is chosen.
- The solar energy analysis shows which façades are most exposed to solar radiation and estimates how much power panels there could produce in a year.
- The analysis accounts for the surrounding terrain, vegetation and buildings, and for the climate.
- Runs in a web browser and is aimed at the pre-design and schematic design phases.
DesignBuilder
Modelling BIPV as part of the building envelope in a whole-building energy simulation.
- BIPV is defined as constructions in a Building Integrated Photovoltaics category, or as glazing in a Glazing Integrated Photovoltaics category, with the PV properties on the outermost layer.
- The Model Data Grid View applies BIPV constructions to particular façades by slope, orientation or tag.
- The Simulation module runs EnergyPlus simulations for energy and comfort analyses.
Good to know
- Each BIPV construction or glazing needs a generator of its own; any not selected in a generator produces no electricity.
Solarius PV
Designing a PV system on the BIM model of a building, façades and brise-soleil included, with IFC in and out.
- Designs PV on façades and sunscreens (brise-soleil) of new or existing buildings, on IFC models imported from Revit, ArchiCAD or Edificius, and exports the system as IFC.
- Shading from the horizon and from nearby obstacles drawn in 3D, with row spacing on horizontal, inclined or vertical surfaces.
- Irradiation from Meteonorm 7.1 or PVGIS (SARAH3 or ERA5), or an imported typical-year file.
PVsyst
Detailed yield simulation of a PV system with a 3D scene, once the modules, strings and inverters are known.
- Near shading is computed from a 3D scene of the system and its surroundings, modelled in PVsyst or imported from a CAD tool, at every time step for beam, diffuse and reflected light.
- For the direct beam, shading losses are split into the irradiance deficit and the electrical mismatch between modules and strings.
- Thermal losses are set with a heat-loss factor that depends on the mounting mode, façade among the modes listed; PVsyst suggests 15 W/m²K for a fully insulated back side, against 29 W/m²K for an open rack.
- Its orientation options include arrays of sun-shields on a façade; the unlimited sun-shields mode is suited only to perfectly south-oriented façades.
Good to know
- Runs only on Windows (8, 10 and 11); the vendor gives separate instructions for Mac users.
See your site's climate before design begins
Pin any location and get climate, comfort and preliminary energy insight your whole team can read. Start with a 7-day free trial, or book a 30-minute demo.
Free plan; paid plans from €59/month (cancellation takes effect after 12 billing cycles) or €599/year, with a 7-day free trial. No card required. If you add a card during the trial, the plan is charged when the trial ends; otherwise your account moves to the Free plan. See all plans.
Frequently asked questions
What is façade BIPV?
Building-integrated photovoltaics (BIPV) are PV modules that are part of the building envelope rather than mounted on it: ventilated cladding, curtain-wall spandrels, coloured or printed glass panels and similar. On a façade they replace a material the wall would need anyway, so the case for them rests on both the electricity and the cladding they replace.
How does the window-to-wall ratio affect façade PV potential?
Opaque PV modules can only go on the wall between the windows, so every point of window-to-wall ratio takes area away from them. C4B's BIPV Façade Potential computes the remaining opaque area level by level and façade by façade; tools such as DesignBuilder can also model PV integrated in the glazing itself.
Which façade produces the most?
It depends on the site's latitude and climate, but façades facing the equator usually collect the most, east and west façades less, and façades facing the pole far less per installed kW. That is why tools keep façades separate and why C4B reports energy per façade and the building orientation that maximises the total. For close comparisons, such as east against west, the technical view's detailed models give a more precise answer.
Do coloured BIPV modules produce less?
Usually, yes, by an amount that depends on the product and the colour, so check the maker's datasheet. C4B's BIPV Façade Potential applies no colour factor of its own: it uses the power per square metre that the makers print for their coloured or printed products, so the colour is already in the estimate.
When do I need another tool alongside C4B?
When the surroundings or the building's shape matter. C4B's BIPV Façade Potential, in its technical view, can run the full hourly model chain (IEC, PVGIS or NREL SAM models) with exact windows, a verified product or a custom panel on each façade, and the inverter and losses. It treats each façade as a free vertical plane on a rectangular building, so shade from neighbouring buildings, balconies or other façades, curved or inclined façades, and several orientations wired to one inverter input are not modelled. For those cases a 3D or BIM tool such as BIMsolar, Solarius PV or PVsyst adds the geometry.
Sources
We make C4B. Information about the other tools comes from their official websites and documentation, checked on 9 October 2026. Products and prices change, so check each vendor's site for the latest details. All product names belong to their respective owners.
- Ladybug Tools: about and FAQ
- Ladybug Tools: Ladybug features
- Ladybug Tools: Honeybee features
- Ladybug Tools: Honeybee Photovoltaic Properties component
- BIMsolar: FAQ
- BIMsolar: plan and pricing
- PVSITES project: BIMsolar and PVSITES plugins
- Autodesk Forma blog: what is Forma Site Design
- Autodesk Forma blog: solar energy analysis
- DesignBuilder: PV systems help (v2025.1)
- DesignBuilder: product overview
- DesignBuilder: annual single-user licences
- DesignBuilder: purchasing FAQs
- Solarius PV: product page
- Solarius PV: plans
- PVsyst: product page
- PVsyst: shop
- PVsyst: shadings help
- PVsyst: heat transfer coefficients (U-values)
- PVsyst: buy a licence
- PVsyst: plane orientation modes
Related on C4B
Solar radiation and PV potential
Direct, diffuse and global solar radiation, yearly PV potential, optimal panel orientation and geothermal ground temperatures.
Sun path diagram
Sun path diagrams in 2D, 3D and globe views, together with monthly daytime cloud cover.
C4B vs Ladybug Tools
Ladybug is a free, flexible Grasshopper toolkit; C4B is a ready-made browser workflow from an address to a climate report.
C4B vs Forma Site Design
Forma Site Design analyses massing models in the Autodesk cloud; C4B profiles a site's climate from an address, before any model exists.