RC solar-powered plane without batteries powered by solar cells
Solar DR1 RC solar airplane kit — the first Italian RC aircraft flying on solar power alone, with no propulsion battery. SunPower back-contact monocrystalline cells power the brushless motor directly. Built and sold since 2017. Supplied to universities and aeronautical research institutes.
Wingspan 51.2 in (130 cm) · Weight 17.6 oz (500 g) · Wing loading <15 g/dm² · 20 SunPower cells in 20S configuration · Motor, ESC, servos, propeller and illustrated manual included.
In the spring of 2017, MR WATT achieved something no RC manufacturer had done before: a model aircraft that flies on solar power alone — no propulsion battery, no recharging breaks, no limits as long as the sun shines. The Solar DR1 is that aircraft. Built and sold since 2017, it has been supplied to universities and aeronautical research institutes across Europe and beyond for autonomous solar flight studies.
This is not a toy. It is a serious engineering kit for RC pilots and makers who want to build and fly a genuinely battery-free solar airplane using SunPower back-contact monocrystalline cells — the same high-efficiency cell technology used in MR WATT's professional photovoltaic panels.
How pure solar flight works
Twenty SunPower cells are mounted across both wings in a 20S series configuration (10 per wing, arranged in a 5×5 rectangle). In full sunlight they generate approximately 10V at 5A, driving the brushless motor directly — no battery in the power circuit. Flight duration is limited only by available sunlight and the transmitter battery. For beginners or variable-light conditions, the kit includes a U-BEC 5A and a 7.4V LiPo to power the RC receiver only, keeping the pilot in full control without affecting the solar propulsion concept.
What makes the Solar DR1 unique
- Genuine battery-free propulsion — solar cells feed the motor directly. No ESC waiting for stored charge: power in = thrust out, in real time
- SunPower back-contact monocrystalline cells — highest efficiency per gram available in RC-scale solar. The same cells MR WATT uses in custom professional PV panels
- CNC-cut depron and carbon structure — wings pre-cut in their shells, 6mm carbon spar, 6mm depron fuselage. Total weight: 500g. Wing loading: under 15g/dm²
- Elevon configuration, no V-tail — the V-tail was removed because it casts shadows on the cells and reduces output. Elevons allow basic aerobatics: loops, rolls, tight turns
- University-tested — supplied to academic and aeronautical institutions for research. A 2150mm version was built for a coastal surveillance project on the island of Anguilla, capable of carrying 500g of payload while flying on solar power alone
Solar DR1 Technical Specifications
| Model ref. | SF-DR1 |
| Wingspan | 51.2 in (130 cm) |
| Wing chord | 13 in (33 cm) |
| Total weight | 17.6 oz (500 g) |
| Wing loading | <15 g/dm² (very low — docile handling) |
| Solar cells | 20 SunPower back-contact monocrystalline (+2 spare) |
| Cell configuration | 20S — 10 cells per wing, 5×5 rectangle |
| Solar output | ~10V / ~5A in full sun |
| Motor | Brushless (included) |
| ESC | Brushless speed controller (included) |
| Servos | 2 (included) |
| Wing structure | CNC-cut depron + 6mm carbon spar |
| Fuselage | 6mm CNC depron |
| Control surface | Elevon (no V-tail) |
| RC gear required | TX + RX only (not included), min. 2 channels |
| In production since | 2017 |
What's in the box
- 2 CNC-cut depron semi-wings
- 1 CNC depron fuselage assembly kit
- 1 plywood firewall (3mm)
- 1 Bowden cable (1m)
- 1 carbon spar (6mm)
- 2 depron ailerons
- 2 control horns
- 22 SunPower solar cells (20 + 2 spare)
- Cell soldering accessories (ribbon wire, flux, connectors)
- 2 servo motors
- 1 brushless motor
- 1 brushless ESC
- 1 propeller
- 1 illustrated assembly manual
- 1 U-BEC 5A (for receiver power)
- 1 LiPo 7.4V battery (for receiver power)
Frequently Asked Questions
Does it really fly with no battery at all?
For propulsion: yes. The SunPower cells on the wings power the brushless motor directly, with no energy storage in the propulsion circuit. The 7.4V LiPo included in the kit powers only the RC receiver — it plays no role in driving the motor. In full sunlight the plane flies indefinitely. This was first demonstrated publicly in 2017 and has been replicated in university research programs since.
How difficult is the build?
Intermediate level. The wings and fuselage are CNC pre-cut — assembly is straightforward with glue, tape, and basic hand tools. The most skilled step is soldering the solar cells in series (10 per wing in a 5×5 grid). The kit includes all soldering accessories and an illustrated step-by-step manual. No prior experience with solar cells is required, but basic RC model building skill is recommended.
What do I need to buy separately?
Only the RC transmitter (TX) and receiver (RX), minimum 2 channels. Everything else is in the kit: motor, ESC, servos, solar cells, soldering accessories, carbon spar, assembly manual, and the LiPo + U-BEC for receiver power.
Can it do aerobatics?
Yes — basic aerobatics. The elevon configuration (V-tail was intentionally removed to eliminate cell shading) gives the Solar DR1 clean control authority for loops, barrel rolls, and tight turns. The very low wing loading (under 15g/dm²) makes the aircraft light and responsive. It is not designed for high-speed 3D flying, but it handles confidently in the hands of an intermediate RC pilot.
Is this suitable for research or university projects?
Yes. The Solar DR1 has been supplied to university departments and aeronautical institutes for autonomous solar flight research. MR WATT has also developed a larger 2150mm wingspan version for payload-carrying applications (drone surveillance, coastal monitoring). If you represent an institution with custom requirements, contact us directly through mrwatt.solar.