One of the most common questions when sizing a solar system is: "How many watts of solar can my Victron MPPT handle?" The answer depends on your battery voltage. This guide provides complete reference tables for every Victron SmartSolar and BlueSolar MPPT model at 12V, 24V, and 48V.
How Maximum Solar Wattage Is Calculated
The maximum solar wattage a Victron MPPT can handle is determined by a simple formula:
Max PV watts = Max charge current × Battery voltage
For example, the SmartSolar MPPT 100/30 at 12V: 30A × 14.4V (typical absorption) ≈ 440W.
If you connect more solar wattage than the controller's maximum, the MPPT simply limits its output to the rated charge current. It won't be damaged, but the excess solar capacity is wasted. That said, slight oversizing (10–20%) can be beneficial — it helps maintain full charge current in less-than-perfect conditions like overcast skies, high temperatures, or non-optimal panel angles.
SmartSolar MPPT Maximum Solar Wattage
| Model | Max Voc | Max at 12V | Max at 24V | Max at 48V |
|---|---|---|---|---|
| SmartSolar 75/10 | 75V | 145W | 290W | — |
| SmartSolar 75/15 | 75V | 220W | 440W | — |
| SmartSolar 100/15 | 100V | 220W | 440W | — |
| SmartSolar 100/20 | 100V | 290W | 580W | — |
| SmartSolar 100/30 | 100V | 440W | 880W | — |
| SmartSolar 100/50 | 100V | 700W | 1400W | 2800W |
| SmartSolar 150/35 | 150V | 500W | 1000W | 2000W |
| SmartSolar 150/45 | 150V | 650W | 1300W | 2600W |
| SmartSolar 150/60 | 150V | 860W | 1720W | 3440W |
| SmartSolar 150/70 | 150V | 1000W | 2000W | 4000W |
| SmartSolar 150/85 | 150V | 1200W | 2400W | 4900W |
| SmartSolar 150/100 | 150V | 1450W | 2900W | 5800W |
| SmartSolar 250/60 | 250V | 860W | 1720W | 3440W |
| SmartSolar 250/70 | 250V | 1000W | 2000W | 4000W |
| SmartSolar 250/85 | 250V | 1200W | 2400W | 4900W |
| SmartSolar 250/100 | 250V | 1450W | 2900W | 5800W |
BlueSolar MPPT Maximum Solar Wattage
The BlueSolar range has identical electrical specifications to the SmartSolar range (same charge current ratings, same maximum wattage). The only difference is the absence of built-in Bluetooth. If you have a BlueSolar model, use the same wattage limits from the table above.
SmartSolar MPPT RS (High-Power Models)
| Model | Max Voc | Max at 48V |
|---|---|---|
| SmartSolar MPPT RS 450/100 | 450V | 6500W |
| SmartSolar MPPT RS 450/200 | 450V | 12800W |
The RS models are designed for large off-grid and commercial systems at 48V only. They support much higher PV voltages (up to 450V), allowing long series strings of standard residential solar panels.
Quick Reference: Common Panel Configurations
Here are the most popular solar panel configurations in the UK and which MPPT handles them on a 12V battery system:
| Panel Setup | Total Watts | Minimum MPPT | Recommended MPPT |
|---|---|---|---|
| 1 × 100W | 100W | 75/10 | 75/15 |
| 1 × 175W | 175W | 75/15 | 100/20 |
| 1 × 200W | 200W | 75/15 | 100/20 |
| 2 × 100W | 200W | 75/15 | 100/20 |
| 2 × 175W | 350W | 100/30 | 100/30 |
| 2 × 200W | 400W | 100/30 | 100/30 |
| 3 × 175W | 525W | 150/35 | 150/45 |
| 3 × 200W | 600W | 150/45 | 150/45 |
| 4 × 200W | 800W | 150/60 | 150/60 |
| 2 × 400W | 800W | 150/60 | 150/60 |
| 5 × 200W | 1000W | 150/70 | 150/85 |
The "Minimum MPPT" column shows the smallest controller that can handle the total wattage. The "Recommended MPPT" gives you some headroom for real-world conditions like high temperatures (which reduce panel output) and slight oversizing to maximise harvest on cloudy days.
Why Higher Battery Voltage Means More Solar Capacity
Notice that every MPPT handles exactly double the solar wattage at 24V compared to 12V, and double again at 48V. This is because the charge current stays the same, but the voltage (and therefore the power) doubles.
This is one of the key advantages of 24V and 48V systems — you can connect significantly more solar panels to the same controller, reducing cost per watt. For systems above 1000W, 24V or 48V battery systems are strongly recommended.
What Happens If You Connect Too Much Solar?
The MPPT simply limits its charge current to the rated maximum. If you connect 500W to a 100/30 on a 12V system (which has a 440W limit), the controller charges at 30A and the excess 60W of capacity is unused. The controller is not damaged.
Deliberate oversizing of 10–20% beyond the maximum is actually common practice. It ensures the controller reaches full output on less-than-perfect days without wasting significant capacity on peak days.
However, never exceed the PV voltage limit. While excess wattage is harmlessly limited, excess voltage will permanently damage the controller.
Summary
Use the tables above to match your solar panel array to the right Victron MPPT controller. Always check both the wattage limit (based on your battery voltage) and the voltage limit (based on your panel Voc and wiring configuration). When in doubt, use the Victron MPPT sizing calculator to verify.
