The ThermaSol outdoor sauna lineup
The Solaris Small is the smaller of ThermaSol’s two off-grid solar cabins. It runs on a 3 kW Harvia KIP heater fed from rooftop solar and a built-in battery bank: no electrical service, no chimney, no recurring wood. For a remote pad where utility runs cost more than the cabin, this is the build.
Spec sheet
- Footprint: 86 by 60 inches, 97 inches tall, 290 cu ft
- Capacity: 2 to 3 adults
- Heater: 3 kW Harvia KIP; Controller: Harvia CX170
- Power: integrated rooftop solar with battery bank
- Glass: solar-tinted panoramic
- Cladding: Tile Oak inside and out, Brushed Alder benches; European-standard insulation
- RGB LED color therapy; Built in Finland by Kirami
Built by Kirami in Finland
Solaris Small is sold in Europe as the Kirami FinVision® -sauna S Zero. Kirami is a family-run Finnish manufacturer that builds these cabins from start to finish at their own factory in Sastamala, Finland. The FinVision® line carries the Finnish Key Flag Symbol (Avainlippu): the credential that certifies Finnish-designed, Finnish-manufactured, and built from Finnish materials.
The Kirami FinVision® Zero line launched in 2024 as the world’s first fully self-sufficient off-grid electric sauna. Triple-pane argon-filled tempered glass, fully insulated walls, and enclosed tiled benches reduce the cabin’s effective heated volume to roughly 5 cubic meters, which is why a small 3-3.6 kW heater can do the work of an 8-10 kW heater in a conventional outdoor sauna of the same exterior footprint.
Kirami joined the Harvia Group in May 2021, so the heater you choose and the cabin it sits in are now sister-company products engineered together. The integrated LED lighting wires into the Harvia Xenio control panel, which means one controller for heat, time, and ambiance.
Finnish ventilation engineering: fresh air enters through the intake on the heater side wall; spent air exhausts through the vent at the opposite upper back corner. Continuous airflow during a session without the cold drafts that plague poorly ventilated outdoor saunas.
Kirami construction details
Triple-pane grey-tinted tempered thermal glass with argon between layers on every window and the door (not just the front). LED light therapy is integrated into the backrest and dimmed from the Harvia CX170 control panel. The cabin’s solar array uses three 410-watt panels feeding two 25.6-volt lithium battery packs. A full charge typically supports 2 to 3 hours of sauna time, or up to 4 to 5 hours in optimal sunny conditions. Kirami describes the design as “maximum energy efficiency, without compromising the authentic Finnish löyly experience” (löyly is the burst of steam when water hits hot stones).
Solar monitoring app
A companion mobile app reports solar yield, battery charge state, and heater status from your phone, so you can check capacity before heading out to a remote site or schedule a session for after a sunny afternoon. The Harvia CX170 controller drives the heater on command once the battery bank has the energy to back it.
FAQ
How many people fit?
Two to three adults.
How long does it take to heat up?
About 45 to 60 minutes from a charged bank, weather and panel condition permitting.
Do I need an electrician?
No. The Solaris ships ready to run from its own solar and battery system.
What’s the warranty?
One year manufacturer warranty.
Can it stay outside year-round?
Yes. Solar yield drops in deep winter; plan sessions accordingly.
What’s the lead time?
Twelve weeks.
Where it shines
This is the cabin we recommend when the site is a hunting lease, a back-forty lake pad, or a guest cabin where running a 240V line would mean a five-figure trench. The Solaris is a closed loop.
Shipping
Free shipping included. Outdoor cabins ship fully assembled via flatbed trailer. A forklift or crane is required at delivery for placement; manual offloading is not recommended due to size and weight. A licensed electrician handles the heater hookup. We notify customers two weeks before scheduled delivery so the site is ready. The path from the truck to the placement pad must be clear and accessible. Pad should be a firm, level surface with slight drainage runoff: concrete, decking, pavers, or compacted gravel.
Optional hands-on installation
If your delivery timing aligns with our calendar, founders Ben Burger or Ben Frizzell will travel to help with the install in person. The Bens have airdropped into builds with customers across the country since launching the marketplace. This is offered for a limited time and depends on schedule availability. Ask before checkout to see whether your delivery window works.
Prebuilt
Sauna Brushes
Vents