One Software for Commercial Roof:

Layout, Shading and Documents in IST PVSolar Simulator V9

The short version

On a typical commercial roof, a designer can now go from a drone image to a signed-off design pack inside IST PVSolar Simulator V9, without opening a second program for the layout, the shading study or the paperwork.

That sentence has a boundary, and this article states it. "Typical" means a flat or pitched commercial or industrial roof, or a small ground area beside it, designed with free satellite weather data. Where a lender insists on a named yield report, or the project depends on paid weather data, a second tool still has a job. The last section says exactly when.

The usual split in a design office is three tools: one to lay out the roof, one to simulate the energy, one to produce drawings and the proposal. Each hand-off is a chance for the module count or the string length to change without anyone noticing. Keeping the roof, the shade and the documents in one project removes those hand-offs.

A commercial roof, start to finish

The whole job runs in nine steps, in one project file.

1. Load the site image. A drone image in JPG, PNG or GeoTIFF. A geo-referenced image sets the scale by itself; the roof boundary can come from a GeoJSON or KML file.
2. Trace the roof and mark its areas. Flat roof areas, pitched faces with their own slope and direction, and ground areas beside the building can sit in the same project.
3. Mark what casts shade. Neighbouring buildings and trees with their height from the ground, rooftop objects with their height above the roof, and parapets, which ask for their height as soon as the line is traced.
4. Choose the equipment and define the sub-arrays. Each sub-array has its own module, inverter, string length and number of inputs, with five electrical checks shown live.
5. Fit the modules. Auto Fit fills each area at its own tilt and direction. Each area is then linked to the sub-array that feeds it.
6. Read the shade. The tool lists every string with the number of shaded modules and the cause, and marks those modules on the plan.
7. Apply the shading to the simulation. One button builds the shading tables for every area and sends them to the energy model.
8. Run the hourly simulation. The loss table fills in with computed values, including shading, clipping and rear-side gain.
9. Produce the documents. Report, drawings, bill of quantities and proposal come from the same project.

Layout: the roof as the designer sees it

The layout tools work on the real site image, so what the designer draws is what the site team will find.

• Heights that mean something. A building or tree is entered with its height from the ground, a stair room or chimney with its height above the roof. Only the part of an object that rises above the modules casts shade on them, so a neighbour lower than the roof casts none.
• Parapets. After a parapet line is traced, a box asks for its height. The same height feeds the edge setback in the pitch design card, and the 3D view draws the wall where it was traced.
• One front-edge height. The module's front-edge height is a single value. Change it once and the side view, the Row Pitch Diagram and the 3D view all follow, with the back-edge height recalculated.
• Mounting height for bifacial modules. Suggest Mounting Height calculates the rear-side gain at every 0.1 m up to 3 m and reports the height where the gain stops rising. It lists the gain at several heights so the designer can choose a practical one.
• Row spacing and sun path side by side. The Row Pitch Diagram and the Sun Path 2D Chart sit next to each other under the plan. The chart shows the hours when any part of the array is shaded.
• A 3D view with the structure in it. Flat-roof and ground modules stand on posts with concrete blocks and tie members. Pitched-roof modules sit on bars, cross-connectors and mounting profiles at the clearance the designer sets. A small N marks north.
• Recent projects. The File menu lists the last ten projects saved or opened in the browser.

Shading: from the plan to the energy number

Shading is where a separate simulation tool was usually needed. The table lists the questions a designer asks about shade and how V9 now answers each one.

The results appear in the loss table after an hourly run. The shading row shows the direct and diffuse parts, the electrical shading row shows the string effect, and the clipping row says when an inverter limit was shared between roof faces.

Three simplifications remain. A module counts as fully lit or fully shaded, judged at its centre. Strings are assumed to follow the rows. The 15% bypass limit is a fixed rule that suits strings wired in parallel.

Documents: what comes out of the same project

Six print-ready documents come from the project the designer just built, so none of them needs the roof or the equipment typed in again.

The same project also exports data files for people who want the numbers: the hourly results for all 8,760 hours, monthly results, the bill of quantities and the year-by-year projection.

The proposal will not print until the simulation and the economics have been run, so the figures in it are the simulated ones.

The takeaway

A designer's day on a commercial roof is mostly three things: where the modules go, what shades them, and what gets handed to the client and the site team. IST PVSolar Simulator V9 now does all three in one project.

The gain is not only time. The module count in the proposal is the count on the plan. The sub-array the shading study ran is the sub-array in the wiring diagram. The parapet in the 3D view is the parapet in the energy number.

Try it on one live roof this month. Trace it, mark what shades it, fit the modules, apply the shading and print the pack. Then decide, from the list above, whether that project needs anything more.