Comparison
Ritwerk and OpenSolar, side by side.
OpenSolar is a no-cost platform for design, sales and projects, funded by partners. The designer is a solar designer with string checks, mounting and loads in the same drawing.
Updated
What OpenSolar is
OpenSolar is a platform for solar companies with design, quotes and project management. It costs installers nothing; manufacturers, finance companies and distributors pay to be included. According to OpenSolar, over 28,000 professionals use the platform, in more than 185 countries.
New projects are drawn on imagery from the Google Solar API. Imagery from other providers is bought per project: Nearmap in Australia, New Zealand, the USA and Canada, and photorealistic 3D in the UK and parts of Europe, among others. According to the help centre, yield is calculated with NREL’s PVWatts and SAM, hour by hour.
Side by side
| Ritwerk | OpenSolar | |
|---|---|---|
| Runs in | The browser, on a computer and iPad, with no account | Cloud platform with an account; mobile app for customer details and quotes |
| Components | Register of 570 products (120 panel models, 415 inverters, 35 batteries) from many manufacturers, with product sheets and datasheets; you can add your own panels | Components from many manufacturers, who pay to be included; size: not stated |
| Base data | Aerial imagery from Esri; the outline is traced on the photo and Inner edges raises the roof in 3D | Google Solar API as standard; imagery bought per project (Nearmap outside Europe, 3D Plus in parts of Europe) |
| Shading | The sun’s path every month plus sky view, at nine points per panel; the loss per panel | Sun path over the day, month and year, shading down to substring level; hourly over the year |
| Strings | Longest strings within Voc at −25 °C, Vmp at 70 °C and the current per MPPT, with an explanation | Manual and automatic |
| Yield data | PVGIS 5.3 from the European Commission, simulated hour by hour | PVWatts 6 and SAM, hourly; weather data source outside the USA: not stated |
| Mounting and loads | Snow and wind loads to the Swedish BFS 2024:6 in the designer: zones, fixings and largest c/c spacing for 12 systems from Nordmount, SOLTOP and Weland; ballast in the manufacturer’s software | Mounting tool with 13 manufacturers, assessment of structure and wind load; snow is not mentioned |
| Battery | Battery sizing tests every size hour by hour; control by hourly price in SE1–SE4 | Hourly battery simulation, time-of-use tariffs; EV and heat pump in the quote |
| For the customer | PDF report in A4 at three levels, with a 3D view, strings, yield, shading and economics | Quote with your own branding, 3D view and e-signature (DocuSign, PandaDoc) |
| Interface | Swedish, English and German | Not stated; quote languages in beta, around twelve |
| Price | Designer at no cost; Pro €49 per user per month excl. VAT, with volume discount (pre-order) | No charge; Enterprise services from USD 500 per month, API and integrations charged since April 2026 |
The details on OpenSolar come from the vendor’s own pages and were checked on 13–14 November 2026; the sources are listed at the end of the page. "Not stated" means the detail could not be verified there. The Ritwerk column describes the designer as it is today.
When OpenSolar is the better fit
When your company wants design, quotes and sales in one platform that costs nothing. The quote carries your own branding, an interactive 3D view and acceptance directly in the quote, with e-signature via DocuSign or PandaDoc. Battery, EV charging and heat pump can be part of the same quote.
OpenSolar also has a mounting tool linked to 13 mounting manufacturers, with material quantities and an assessment of structure and wind load. The countries listed there include Germany, the Netherlands, Poland, Spain and the UK.
When Ritwerk is the better fit
When the strings and the loads need to be settled before the proposal goes to the customer. The designer checks every string against the inverter’s datasheet – Voc at −25 °C, Vmp at 70 °C and the current per MPPT – and calculates snow and wind loads per zone on the roof to the Swedish BFS 2024:6, for mounting systems from Nordmount, SOLTOP and Weland.
Yield comes from PVGIS 5.3, the European Commission’s open service, and is set against the customer’s consumption hour by hour. The interface is available in Swedish, English and German, and the PDF report shows customers their own house in 3D with the figures behind the proposal.
The roof from the outline
You click around the house on the aerial photo and press Inner edges. The designer derives the ridges, hips and valleys from the outline and raises the roof in 3D. Then you drag the ridge until it matches the house, and every roof face follows.
Sources
- OpenSolar – home page (no cost, countries) – checked 14 November 2026
- OpenSolar – Is OpenSolar Really Free? – checked 14 November 2026
- OpenSolar – OpenSolar Pro (number of users) – checked 14 November 2026
- OpenSolar – Enterprise Services (prices) – checked 14 November 2026
- OpenSolar – fee for API and integrations from 16 April 2026 – checked 14 November 2026
- OpenSolar – Google Solar API as standard – checked 14 November 2026
- OpenSolar – Imagery Marketplace – checked 14 November 2026
- OpenSolar – Auto Design (3D, shading) – checked 14 November 2026
- OpenSolar – Mounting Designer – checked 14 November 2026
- OpenSolar – the quote (Sales Machine Proposal) – checked 14 November 2026
- OpenSolar – release 3.12, October 2026 (mobile, e-signature) – checked 14 November 2026
- OpenSolar – release 3.7.0 (quote languages) – checked 14 November 2026
- OpenSolar Help Center – How is Output Calculated in OpenSolar? – checked 13 November 2026
- OpenSolar Help Center – Stringing, Micro-Inverters, and Power Optimizers – checked 13 November 2026
- OpenSolar Help Center – How OpenSolar Models Battery Energy Storage – checked 13 November 2026
- OpenSolar Help Center – How to create a tariff in OpenSolar – checked 13 November 2026
Questions and answers
Questions and answers
Does OpenSolar cost anything?
Not for design, sales and project management, according to OpenSolar. Services for larger companies cost from USD 500 per month, API access and integrations with other systems have been charged since April 2026, and imagery from other providers is bought per project.
Which weather data does OpenSolar use?
OpenSolar’s help centre describes PVWatts 6 with hourly resolution and a typical weather year, and SAM for designs in 3D. Which weather data source is used outside the USA is not stated on the pages we could read.
Which languages is OpenSolar available in?
OpenSolar’s website is available in English, Spanish, German, Italian and Hindi, and quote languages are available in a global beta with around twelve languages. Which languages the interface itself has is not stated on the pages we could read.
Does Ritwerk produce a quote?
Ritwerk produces a PDF report in A4 with a 3D view, yield, shading and economics, and calculates the savings and payback period from the price you enter. Deductions and terms belong in the quote, which you produce in your own quoting tool.
Read next
- The roof in 3DOutline on aerial imagery, Inner edges and the ridge in 3D – gable, hipped, mansard, flat and your own roof lines.
- Mounting and loadsSnow and wind loads to BFS 2024:6: wind zones, fixings per panel and the largest c/c spacing per roof face.
- PDF customer reportCover with a 3D view, plan drawing, shading, yield and economics – short, standard or full.
Try it on a real roof.
The designer opens in your browser, with no account. Search for an address and start drawing.