Complete technical data sheet for SolBox, the DC MPPT controller by AXINAR that feeds the resistance of a standard electric water heater directly from photovoltaic panels. No inverter, no grid connection, no permits.
70Vmax DC input
6panelsup to ~3,500 W
85°Cconfigurable setpoint
10yearscontroller warranty
00Summary
SolBox is a DC MPPT electronic controller that feeds power directly from photovoltaic panels into the resistance of any electric water heater (100 L–500 L). It runs stand-alone, no inverter, no grid connection, no installation permits. Manufactured in Thessaloniki, Greece, with a 10-year warranty.
01Electrical
What goes in, what comes out.
- Input voltage (DC)
- up to 70 V
- Input from
- PV panels (direct DC, no inverter)
- Panels supported
- up to 6 units
- Panel wattage
- 400–620 W per panel
- Total array power
- up to ~3,500 W
- Output
- DC into water heater resistance
- MPPT algorithm
- P&O (Perturb & Observe)
- MPPT tracking rate
- 2 times per second
- Idle grid draw
- None, no grid consumption when standing by
- Auxiliary supply
- Self-powered up to 2 panels in series or 2 + 2; above that the included 12 V / 3 W supply is used
02Protection & Safety
What keeps the unit and the tank out of trouble.
- Surge protection
- Included
- Lightning protection
- Included
- Overheat behaviour
- Energy transfer stops at the setpoint, the water never boils
- Anti-freeze protection
- Auto-activates below 5 °C, cuts off at 8 °C
- Temperature sensing
- External water temperature sensor, ~1.5 m cable
- Fault handling
- Fault notifications and remote diagnostics through the app
03Mechanical
The box on the wall.
- Dimensions (W × D × H)
- 14.5 × 9.5 × 14.5 cm
- Weight
- 2.5 kg
- Enclosure material
- Sheet metal, powder coated
- Mounting
- Wall-mounted, near the water heater
- Cooling
- Passive (no fan)
- Output cable
- Pre-fitted, ~1.5 m
04Water Heater Compatibility
It works with the tank you already own.
- Boiler capacity range
- 100 L – 500 L
- Recommended capacity
- 150 L and above
- Resistance type
- Standard 220 V electric resistance (2,000–4,500 W)
- Equipment replacement
- None, uses your existing water heater
- Extra plumbing
- None, only electrical connection
- Backup heat source
- Grid, boiler or buffer tank, switched automatically
05Operational
Day-to-day behaviour.
- Water temperature setpoint
- User-configurable, up to 85 °C
- Two independent setpoints
- Sun + backup source (e.g. grid)
- Scheduling
- 4 independent 24-hour programs
- Holiday scheduling
- Annual calendar, automatic shutdown on chosen days
- Behaviour when no sun
- Water heater keeps working on grid power
- Cloudy-weather behaviour
- Produces hot water from as little as ~10 W off the panels
- Maintenance
- None
06Connectivity
Control from the phone.
- WiFi
- 2.4 GHz
- Mobile app
- iOS + Android
- Remote control
- Setpoints + schedule adjustments
- Monitoring
- Energy produced, water temperature, statistics
07Installation
What the job on site looks like.
- Installation type
- Off-grid, no connection to the electrical grid
- Permits / net-metering
- None, and net metering is unaffected (not a grid-tied system)
- Installer
- Certified SolBox installer or licensed electrician
- Installation time
- Typically 3–5 hours, about 40% less than a conventional solar system
- Wiring
- DC from panels to SolBox, output to the resistance
- DC cable (not included)
- 4 mm² or 6 mm², depending on the run to the panels
08Warranty & Lifespan
How long it is covered, and by whom.
- Controller warranty
- 10 years
- Expected service life
- 12+ years
- Panel performance warranty
- 20–25 years (from the panel manufacturer)
- Board-level repair
- In-house, the unit is designed and built by AXINAR
- Service
- AXINAR, Thessaloniki, Greece
09Manufacturing
Where it is made and how.
- Country of manufacture
- Greece
- Production site
- Thessaloniki
- Manufacturer
- AXINAR A.E.
- Founded
- 2010
- Manufacturer certifications
- ISO 9001:2015, ISO 14001:2015
- Enclosure process
- Fibre laser cutting, CNC milling, press-brake forming, TIG welding, powder coating
10Sizing
How many panels a given tank needs, and which kit matches.
| Panel configuration | What it covers | Matching version |
|---|---|---|
| 2 panels in series | 150 L in summer, self-powered | SolBox Light |
| 2 + 2 panels | 200 L reaching into spring and autumn, or 150 L under partial cloud | — |
| 3 panels in series | 150 L and 200 L comfortably in summer | SolBox Family |
| 6 panels, 3 + 3 in series | Maximum output of the unit, 300 L under partial cloud, longest season | SolBox Pro |
- Panel brand and type are unrestricted. Between 2 and 6 panels depending on tank size and how much of the year you want covered.
- Sizing above is indicative. The SolBox Configurator works it out from your tank, household size and location.
- Terms used on this page are defined in the AXINAR glossary. Further questions are answered in the SolBox FAQ.
- Document Rev. 2026-10. Specifications are subject to change without notice.