Notes/03
ProductMar 2026·6 min read

Building Photovic: fifty PV proposals in twenty minutes

What we learned building a solar-proposal engine for DACH installers — solar APIs, component compatibility, and why the bottleneck is rarely the panel maths.

DACH PV installers spend roughly four hours per proposal — sourcing roof maps, calculating orientation, picking a compatible BOM, drafting the cover letter. At thirty inquiries a week, that is a full-time engineer doing the kind of work no engineer wants to do.

Photovic started as a hypothesis: if you can draw a polygon on the map and have the system return fifty fully-specified PV proposals in twenty minutes, the installer's day stops being about Excel and starts being about closing.

The map layer

We pulled solar insights from public APIs and overlaid them with the installer's own service zones. For every roof in scope we compute orientation, tilt, panel-area envelope and shading. The installer sees a heat-map before any human has touched a single building.

Specificity converts. Vague calculators are everywhere. Telling a homeowner the exact panel layout for their roof — rather than a kWp estimate — is a different product.

The compatibility engine

The harder problem isn't the maths. It's that 50+ inverters, 30+ batteries and a dozen mounting systems do not freely mix. Voltage windows, current limits, warranty pairings, mounting compatibility — get one wrong and the installer eats it on site.

We encoded the compatibility matrix as machine-readable tier rules and let the engine pick a BOM that is buildable by construction. Spec errors fell to zero.

Where it is now

Photovic is live with installers across Austria and southern Germany. Median proposal time is twenty-four seconds. We are wiring it into ERPs next so that an accepted proposal flows straight into procurement without re-keying a single line item.

G
Georgiy
Founder, propagandas.studio · Vienna, AT
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