The ThermaSol outdoor sauna lineup
The Solaris Medium is the four-to-five-person off-grid cabin in the ThermaSol line. Same Harvia KIP heater and solar-and-battery system as the Solaris Small, scaled up to a square 86 by 86 inch footprint with 415 cubic feet inside.
How the off-grid system works
Rooftop panels feed an onboard battery bank that powers the 3 kW Harvia KIP heater through a CX170 controller. No 240V drop, no chimney, no recurring wood. Heat-up runs 45 to 60 minutes from a fully charged bank. Yield drops in winter and on overcast weeks, which is the trade-off of off-grid; we curate at the build-spec level and would rather you know that up front.
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.
Spec sheet
- Footprint: 86 by 86 inches, 97 inches tall, 415 cu ft
- Capacity: 4 to 5 adults
- Heater: 3 kW Harvia KIP; Controller: Harvia CX170
- Cladding: Tile Oak inside and out, Brushed Alder benches
- Glass: solar-tinted panoramic; RGB LED color therapy
- Power: integrated solar with battery bank; Built in Finland by Kirami
Built by Kirami in Finland
Solaris Medium is sold in Europe as the Kirami FinVision® -sauna M 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
Same triple-pane argon-filled tempered glass construction as the Solaris Small, applied across the larger footprint. LED light therapy in the backrest; the Harvia CX170 control panel handles heat, timing, and lighting from a single interface. Solar system uses three 410-watt panels and two 25.6-volt lithium battery packs; a full charge typically delivers 2 to 3 hours of bathing or 4 to 5 hours in optimal sun. A companion Bluetooth app reports panel yield, battery state, and heater status in real time. Kirami’s framing: “modern design and practicality, combining Finnish traditions with sophisticated European aesthetics.”
FAQ
How many people fit?
Four to five adults.
How long does it take to heat up?
About 45 to 60 minutes from a charged bank.
Do I need an electrician?
No. The system is self-contained.
What’s the warranty?
One year manufacturer warranty.
Can it stay outside year-round?
Yes; expect reduced solar yield in deep winter.
What’s the lead time?
Twelve weeks.
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