The buildings can be constructed in less than four weeks on-site, according to the start-up.

A French start-up which is offering zero-carbon wooden homes complete with solar rooftops has raised €1.5 million from private and institutional investors in its latest funding round.

Solaire Box said new investors included Paris-based venture capital companies Inco and the Inter Invest fund as well as individuals via the Sowefund crowdfunding platform.

“These funds enable us to include additional innovative features to our product and to increase the market share of our new range of zero-carbon houses, first launched in October 2019,” said Solaire Box CEO Thomas Coquil.

The product is a wooden house the company has been developing for five years. “After constructing 100 garden studio and house projects since its launch in 2015, Solaire Box is looking to build 635 houses by 2023,” said Coquil.

A real house

The house, which has a pre-fabricated structure made from French-grown Douglas fir timber and wood fiber, can be built in less than four weeks on-site, according to its manufacturer. “Our Solaire Box, however, must not be considered … pre-fabricated houses, as they are real houses,” the company’s marketing director, Charline Balfourier, told pv magazine. “These houses respect the same rules as traditional concrete or brick houses: creation of foundations, request for a permit, ten-year insurance and a Contrat de construction de maison individuelle.” The latter is France’s main standard form of building contract for new houses.

Balfourier said owners can connect to the grid if they choose. If not, she said, “we install lithium-ion batteries to store the energy produced [by the PV rooftop].”

The marketing director added: “Some of our customers choose this option when they are far from the public network but we do not recommend it by default because it implies having another power generator and this goes against our ecological philosophy.”

The wooden solar house costs €1,700-2,000 per square meter.

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The solar roof

The PV system used can have a generation capacity of 6-9 kW and features solar modules from French manufacturer Systovi and mounting systems by French specialist IRFTS Solutions.

“We usually … install 9 kW for a house unless explicit request is made by our client who would like a lower power, but even in this case, the solar panels cover a majority of the roof,” Balfourier said. “We usually install 30 modules on the roof of our houses or studio, with a power of 300 Wp for each, to reach a total power of 9 kW.”

Solaire Box typically uses Systovi’s V-SYS Pro monocrystalline and polycrystalline PV modules. These panels have a power output of 250-300 W and efficiencies of 17.01-18.4%.

“The wooden structure of the roof is manufactured in the factory, then the mounting structures are installed [at] the construction site and then the solar panels are deployed,” Balfourier said. “The solar panels cover the entire south section for two-sided roofs or the entire section for a single-slope roof, and also make the roof waterproof.”

Expansion

“At the moment we are only building our houses in France but plan to implement in many [of the] world’s different regions,” Balfourier added.

Of the €1.5 million the company recently raised, around €600,000 came from Inter Invest Capital and will be devoted to the development of the Solaire Box subsidiary in the Antilles and French Guyana which was established in 2017.