The ThermaSol Solaris Sauna Cabin is the world's first fully solar-powered, off-grid electric sauna available in the United States and it was recognised by TIME magazine as one of the Best Inventions of 2025 for its breakthrough in sustainable wellness. The Solaris requires no power connection of any kind. Integrated solar panels on the roof and one side wall charge an onboard battery pack that powers the heater, lighting, and control system entirely from sunlight. Place it anywhere the sun reaches a backyard, a patio, a lakeside retreat, a rooftop and it works. No electrician, no trenched conduit, no utility hookup, no electricity bill per session.
Fully off-grid one day of sunlight charges the system
The Solaris solar energy system is integrated directly into the cabin structure. Solar panels cover the roof and a portion of one exterior wall, maximising collection surface without requiring separate panel installation. The onboard battery pack stores enough energy from a single day of sunlight to power multiple sessions. Power levels are monitored in real time through the Harvia mobile app you can see exactly how much charge is available before deciding to run a session, anywhere, from your phone. For locations with variable sun exposure, the Solaris is also available as a low-energy model that supplements mains power rather than replacing it entirely, reducing electricity consumption significantly while keeping operational flexibility. The Harvia Xenio CX45 digital control panel with Wi-Fi integration manages both heater settings and lighting from a single intuitive interface, controllable via app or directly on the panel.
Tile Oak cladding exterior and interior, modern and UV-resistant
The Solaris uses Tile Oak cladding on both the exterior and interior surfaces a modern, tile-like material that is UV-resistant, easy to clean, and visually distinct from any other sauna in the ThermaSol range. The contemporary grid-like finish reads as architectural and forward-looking from outside, and provides a tiled, spa-like interior that contrasts interestingly with the warm alder wood of the benches. The tile cladding is designed for long-term outdoor durability without the maintenance that natural wood exteriors require no staining, sealing, or periodic treatment. A solar-tinted panoramic glass wall spans the full width of the front face, bringing in warm, diffuse natural light while maintaining visual privacy from outside. Inside, an alder-framed window adds a warm natural wood detail to the contemporary tile interior.
Brushed Alder benches soft texture, warm material, European-inspired
Inside, the upper and lower benches and backrests are made from brushed Alder a light, European hardwood with a soft, even texture that is characteristically comfortable at sauna temperatures. Alder has a finer grain than aspen and a warmer natural tone, and the brushed finish enhances that softness. The 24-inch bench depth on both sizes provides generous seating room for extended sessions. The Harvia KIP 3kW electric heater is compact and wall-mounted chosen specifically for the Solaris for its energy efficiency at low wattage, making it ideal for solar-battery operation. Despite its compact size, the KIP provides fast, consistent heat with a built-in stone guard and supports the traditional Finnish Löyly ritual add water to the hot stones for a burst of steam.
Two sizes place it wherever the sun shines
The Solaris is available in Small (2–3 person, 60"W) and Medium (4–5 person, 86"W). Both sizes share the same 86" depth and 97" height, and the same solar energy system, heater, lighting, and control configuration. Both arrive fully assembled on a flatbed trailer. Unlike every other ThermaSol cabin, the Solaris does not require a licensed electrician for heater connection because the Harvia KIP heater operates entirely on the onboard solar battery system. Site preparation is equally simple: a firm, level surface with slight runoff for drainage, and access for forklift or crane off-loading. That is the complete installation for the Small and Medium Solaris.
The world's first fully solar-powered, off-grid electric sauna recognised by TIME as one of the Best Inventions of 2025. Solar panels on roof and side wall, onboard battery pack, Harvia KIP 3kW heater with Wi-Fi, Harvia Xenio CX45 digital control, Tile Oak exterior and interior cladding, brushed Alder benches, solar-tinted panoramic glass wall, RGB LED colour therapy, and Harvia app power monitoring. Small: 60"W × 86"D × 97"H (2–3 people, 2,756 lbs). Medium: 86"W × 86"D × 97"H (4–5 people, 3,064 lbs). No electrical connection required. Arrives fully assembled. Crafted in Finland. 1-year warranty.
World's first solar-powered off-grid sauna TIME Best Inventions 2025 Small: 2–3 people | Medium: 4–5 people No electrical connection required Solar panels - roof + side wall Onboard battery pack Harvia KIP 3kW Wi-Fi heater included Harvia Xenio CX45 control panel Harvia app - power monitoring + control Tile Oak exterior & interior Brushed Alder benches Solar-tinted panoramic glass wall RGB LED colour therapy Fully assembled turnkey Crafted in Finland 1-year warranty
Specifications
Small 2–3 Person (60"W)
| Exterior width |
60" (1,524 mm) |
| Exterior depth |
86" (2,184 mm) |
| Exterior height |
97" (2,464 mm) |
| Capacity |
2–3 people |
| Assembled weight |
2,756 lbs (1,250 kg) |
| Shipping weight |
2,976 lbs (1,350 kg) |
Medium 4–5 Person (86"W)
| Exterior width |
86" (2,184 mm) |
| Exterior depth |
86" (2,184 mm) |
| Exterior height |
97" (2,464 mm) |
| Capacity |
4–5 people |
| Assembled weight |
3,064 lbs (1,390 kg) |
| Shipping weight |
3,285 lbs (1,490 kg) |
Power system
| Power source |
Solar panels + battery pack fully off-grid |
| Solar panel location |
Roof + one side wall (integrated) |
| Battery charge time |
Single day of sunlight |
| Power monitoring |
Harvia mobile app real-time battery level |
| Low-energy option |
Available solar + battery supplement to mains |
| Electrical connection |
Not required fully off-grid |
Construction & materials
| Exterior cladding |
Tile Oak UV-resistant, modern, durable |
| Interior cladding |
Tile Oak easy to clean, tile-finish aesthetic |
| Benches |
Brushed Alder soft texture, European-inspired |
| Bench depth |
24" (610 mm) both sizes |
| Glass |
Solar-tinted panoramic glass wall + full-length glass door |
| Window framing |
Alder wood warm natural contrast to tile interior |
| Use |
Year-round outdoor any sun-exposed location |
Heating, control & lighting
| Heater |
Harvia KIP 3kW compact, wall-mounted, Wi-Fi |
| Heater power |
Solar battery no mains connection needed |
| Stone guard |
Built-in (Harvia KIP) |
| Löyly (steam) |
Yes add water to stones for traditional steam |
| Control panel |
Harvia Xenio CX45 digital, Wi-Fi enabled |
| App control |
Harvia app heater, lighting, battery monitoring |
| Lighting |
RGB LED colour therapy integrated |
Delivery & installation
| Delivery condition |
Fully assembled turnkey-ready |
| Delivery method |
Flatbed trailer curbside |
| Off-loading |
Forklift or crane required manual not recommended |
| Site notification |
2 weeks prior to scheduled delivery |
| Electrician required |
No runs entirely on solar battery system |
| Foundation |
Firm, level surface with slight drainage runoff |
| Lead time |
12–13 weeks (made to order) |
| Origin |
Crafted in Finland to European standards |
| Warranty |
1 year |
Small 2–3 Person (60"W)
Medium 4–5 Person (86"W)
What's included
Fully assembled Solaris Sauna Cabin
Integrated solar panels roof + side wall
Onboard battery pack (solar energy storage)
Tile Oak exterior cladding (UV-resistant)
Tile Oak interior cladding
Brushed Alder upper bench
Brushed Alder lower bench
Brushed Alder backrest
Solar-tinted panoramic glass wall
Full-length solar-tinted glass door
Alder-framed interior window
Harvia KIP 3kW heater (Wi-Fi, wall-mounted)
Sauna stones
Harvia Xenio CX45 digital control panel (Wi-Fi)
Harvia app power monitoring + heater control
RGB LED colour therapy lighting
Full insulation system
Installation manual
Why the Solaris stands out
World's first off-grid solar sauna
No power connection. No electrician. No electricity bill per session. Solar panels on the roof and side wall, onboard battery pack, and Harvia app power monitoring place the Solaris wherever the sun reaches. Recognised by TIME as one of the Best Inventions of 2025.
Solar panels integrated into structure
Solar panels are built into the roof and one side wall no separate panel installation, no racking, no wiring runs to a remote array. A single day of sunlight charges the battery pack for multiple sessions.
Harvia KIP 3kW + Xenio CX45
A compact, energy-efficient wall-mounted heater chosen for solar-battery compatibility. Harvia Xenio CX45 digital control with Wi-Fi manages both heater and lighting. Full Harvia app integration for remote monitoring and control.
Tile Oak modern, durable, easy to clean
Tile Oak cladding on exterior and interior provides UV resistance, durability, and a contemporary aesthetic that requires no wood maintenance. The tiled interior is easy to wipe down after sessions a practical choice for long-term outdoor use.
Brushed Alder benches
European brushed Alder with a soft, even texture and warm natural tone. A 24" bench depth on both sizes provides generous seating for extended sessions. Löyly-compatible: add water to the KIP's hot stones for traditional Finnish steam.
Place it anywhere
Backyard, patio, lakeside, rooftop, remote property anywhere the sun shines, the Solaris works. Arrives fully assembled, requires only a firm level surface. No trenched conduit, no power hookup, no utility infrastructure needed.
About ThermaSol
TIME Best Inventions 2025
65+ years of steam & sauna expertise now fully off-grid.
ThermaSol has been engineering premium steam and sauna systems since 1958. The Solaris Sauna Cabin represents a fundamentally different kind of product from everything else in the ThermaSol range not just a better sauna, but a sauna that changes where and how a sauna can exist. It is crafted in Finland to European quality standards and designed by ThermaSol to be the most accessible off-grid sauna installation possible: no electrician, no hookup, no ongoing utility connection. Arrive with a forklift and a level surface, and you are done.
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World's first off-grid solar-powered sauna TIME Best Inventions of 2025
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Solar panels + battery pack integrated into roof and side wall, one day of sun charges the system
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Harvia KIP 3kW + Xenio CX45 efficient, Wi-Fi controlled, app-monitored
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Tile Oak cladding UV-resistant, modern, low-maintenance inside and out
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Crafted in Finland European standards and materials throughout
About ThermaSol
Sustainable wellness wherever you want it
ThermaSol's mission with the Solaris was specific: remove every obstacle between wanting a sauna and having one. The location constraint you need power where the sauna goes has historically determined where outdoor saunas can be placed. The Solaris removes that constraint entirely. Its solar system, battery pack, and Harvia app monitoring give the owner complete information and complete flexibility. A backyard sauna, a lakehouse sauna, a rooftop sauna, a remote cabin sauna the Solaris works in all of them equally well.
The Solaris arrives via flatbed trailer fully assembled. ThermaSol notifies customers two weeks before the scheduled delivery date. A forklift or crane is required for off-loading given the assembled weight of 2,756–3,064 lbs. The placement surface must be firm, level, and have slight runoff for drainage. No electrical contractor or utility coordination is required before the first session the Solaris is ready to use from the first day of sun after delivery.
Manuals & Documents
Everything you need before and after installation
Download the ThermaSol Solaris Sauna Cabin installation manual below. It covers site selection and preparation, solar panel orientation recommendations, battery pack operation and charging guidelines, Harvia KIP heater and Xenio CX45 control setup, Harvia app pairing for power monitoring and remote heater control, LED lighting setup, and ongoing maintenance for the Tile Oak cladding and brushed Alder benches. No electrical contractor section is required the Solaris operates entirely on its integrated solar battery system.
Installation Guide
Warranty
1-year ThermaSol warranty
The ThermaSol Solaris Sauna Cabin is covered by ThermaSol's 1-year limited warranty, covering defects in materials and workmanship under normal residential use for one year from the date of delivery to the original purchaser. ThermaSol will, at its discretion, repair or replace any covered defective component at no cost. The warranty covers the cabin structure, solar panel integration, and battery pack under normal use and environmental conditions. It does not cover damage from improper installation, misuse, physical damage, or failure to follow ThermaSol's published installation and site-preparation guidelines. The Harvia KIP heater and Xenio CX45 control panel are covered under Harvia's separate manufacturer warranty. Proof of purchase from an authorized dealer is required for all warranty claims. We are an authorized ThermaSol dealer.
