25W Mini Solar Panel with Built-in MPPT Controller
Product Description
The 25W mini solar panel is a compact off-grid power solution with a built-in MPPT (Maximum Power Point Tracking) controller and selectable 5V/6V/9V/12V DC output. It is designed for small low-voltage systems that need better charging performance, stable output, and easier integration in outdoor installations.
Features an integrated MPPT (Maximum Power Point Tracking) charge controller that optimizes charging efficiency compared with basic charging circuits under changing sunlight conditions.
With a high-efficiency 25W monocrystalline module, support for up to six 18650 batteries (not included), and clear LED status indicators, this 25W solar panel is designed to make small solar systems simple, efficient and easy to monitor. The IP66 housing, waterproof button switch and included mounting bracket make it well suited to outdoor use.
Details & Specs
| Item | Specification |
|---|---|
| Solar Panel Type | Monocrystalline silicon |
| Rated Power | 25W |
| Conversion Efficiency | Approx. 23% |
| MPPT Charging | Yes, conversion efficiency improved by about 20% |
| Panel Output Voltage | Approx. 17.5V under load; approx. 21V open circuit |
| Panel Output Current (max) | Approx. 1.2A |
| Power Adapter Charging | Supported |
| Battery Type | 18650 lithium batteries (supports KC batteries) |
| Maximum Battery Quantity | Up to 6 pcs |
| Battery Connection | Parallel |
| Single-Cell Capacity | Supports cells up to approx. 3300mAh |
| Total Pack Capacity | Supports up to approx. 19800mAh (6 × 3300mAh), batteries not included |
| Full Charge Time | Approx. 4 hours (under strong sunlight, typical conditions) |
| Cell Internal Resistance | For 6 cells, internal resistance difference recommended ≤ 0.1–0.2% |
| Minimum Starting Battery Quantity | 1 pc |
| Overcharge Protection Voltage | Approx. 4.28V per cell |
| Overdischarge Protection Voltage | Approx. 3.3V per cell (output stops); approx. 3.0V hardware cutoff |
| Balanced Charging | Supported |
| Charging Voltage Requirement | 16V < charging voltage < 21V |
| DC Output Voltages | 5V / 6V / 9V / 12V |
| DC Output Currents (rated) | 5V 2A / 6V 1.5A / 9V 1.2A / 12V 1A |
| Output Connector Type | 5.5 × 2.1 mm DC output (default) |
| Working Humidity | ≤ 90% RH |
| Ingress Protection | IP66 |
| Weight | Approx. 1.25 kg (excluding batteries) |
| Package Size | Approx. 48 × 29 × 7 cm |
Note: 18650 batteries are not included. For best performance, use cells with similar capacity and internal resistance as recommended.
How to Use
- Install 1–6 compatible 18650 batteries in the battery compartment, observing the correct polarity and using cells with similar capacity.
- Mount the 25W solar panel using the included bracket and angle it toward the sun to maximize exposure.
- Connect your 5V–12V device to the 5.5 × 2.1 mm DC output and select a suitable voltage within 5V/6V/9V/12V on your system if applicable.
- Allow the panel to charge the battery pack in strong sunlight; under typical conditions, a fully matched pack can reach full charge in about 4 hours.
- When needed, you can charge the battery pack through a suitable external power adapter that meets the specified charging voltage range.
Who It’s For
This 25W solar panel is ideal for DIY users, hobbyists and small off-grid projects that need a reliable 5–12V power source. It’s a good fit for low-power electronics, test benches, experimental setups and other situations where running mains power is inconvenient or unavailable.
Care & Maintenance
- Keep the solar surface clean and free from dust or shade to maintain efficiency.
- Use only quality 18650 cells and avoid mixing old and new batteries in the same pack.
- Try to match cells with similar capacity and internal resistance for more balanced charging and discharging.
- Ensure all covers and seals are properly closed to maintain the IP66 protection level in outdoor environments.
- If the panel will not be used for a long period, disconnect loads and store it in a dry place.
