Xantrex Solar
MPPT charge controller sizing tool
Enter panel and array specs to see ranked controller options with rationale.
This is a guidance tool that applies theoretical parameters to help you compare charge controller options. For a final system design or installation, work with a qualified solar installer or contact the Xantrex team for support.
Panel wattage, Voc, Vmp, Imp, and Isc are rated at standard test conditions (STC, 25°C cell temperature), the numbers on the panel's datasheet or label. They are not the values the panel will actually produce in the field, which vary with temperature and sunlight; the results below account for that separately.
Array power
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Array current (Imp)
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Max Array Current (Isc)
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Cold-adjusted Voc
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Array Vmp (STC)
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Recommended options
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| Check | MPPT 30 PRO | MPPT 60 PRO |
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Technical details (for installers and engineers)
Hard limits (block a controller entirely):
- Battery voltage not supported by the controller
- PV open-circuit voltage (Voc), cold-adjusted for the coldest expected temperature and then increased by a 25% safety margin, exceeds the controller's rating
- PV operating voltage (Vmp) too low to charge effectively
- PV short-circuit current (Isc), including a safety margin, exceeds the controller's rated current
Soft considerations (flagged, not blocking):
- PV power above the controller's cap, within an accepted oversizing allowance
- Peak nameplate overpaneling: this describes rated wattage above the cap, not measured energy loss, which depends on sun, temperature, and shading conditions
- Mismatched string orientation or shading
- Battery charge-current acceptance limits by chemistry
Other notes:
- Panel specs and temperature behavior for named panels come from their datasheets; select Custom to enter specs for another brand
- Configurations beyond a 1.3x oversizing ratio aren't offered as a standalone option
- Splitting strings across multiple controllers only helps with power, current, or shading mismatch, not per-string voltage
- When the current wiring cannot run on any single controller, the rewired options keep your panel count and re-check every limit for the new layout
- Strings are never divided between controllers, so the number of controllers is set by how many whole strings each one can carry
- When strings are shared across controllers, the fewest-controller layout may put the busiest controller up to the 1.3x overpaneling ceiling; a no-clipping layout is also shown when it needs more controllers
- Mobile presets set starting defaults only, not measured values
- Each parallel string needs its own fuse, rated no higher than 15A, and a battery-side fuse matching the controller's rated current is required close to the battery. Both are installation requirements, not modeled in this tool
- Battery acceptance uses conservative charge-rate assumptions by chemistry. Confirm against your specific battery's spec sheet
- Sustained heavy overpaneling raises the controller's internal operating temperature, especially with a mostly-full battery and strong steady sun. Running electronics hot for extended periods is a common driver of shorter component life. Good ventilation and airflow around the controller matter more as overpaneling increases
Disclaimer: This sizing tool is provided for general informational and preliminary system-sizing purposes only. Results are based on the information entered by the user and should be verified against the applicable Xantrex product specifications, installation instructions, and system requirements before product selection or installation. Xantrex does not warrant that the calculated results are suitable for every application.