Select Inverter, Mini-Split, or Charge Controller:
Select Solar Panel:
Panel missing?
Select Panel Mounting Method:
How much hotter the cells run than the ambient air: flush roof mounts trap heat (+35 ºC), tilt racks breathe (+30 ºC), ground mounts cool best (+25 ºC). Added to your Max Hot Temp for the hot-weather voltage and current checks.
Mounting Method Temp Adder: —
Is Selected Panel Bifacial? NO
Defaults by mounting: 5% roof mount · 10% roof tilt · 15% ground mount. Applies only to bifacial modules — enter front-side specs as if there were zero gain, or enter gained specs as a custom panel with 0%.
Enter Local Min and Max Temps:
The Min Cold Temp is also called the “Extreme Cold Min” — the coldest morning temp the panels will ever see. Exposing the inverter to a colder temperature when any amount of daylight is present may severely damage the inverter. Be conservative with this value.
“Use my location” fills both values from 30 years of weather history. To verify against official ASHRAE design conditions for your nearest weather station, use the free lookup at ashrae-meteo.info (the UCF Solar Reference Map this industry long relied on was discontinued in December 2025).
For the Maximum High Temp, three standards are acceptable design practice:
- 2% ASHRAE high temperature (most commonly used)
- 0.4% ASHRAE high temperature (required for ETO incentives, more conservative)
- Highest temperature ever recorded (most conservative)
Your Array Report
Panel Specs
- Watts (STC):
- 0
- Watts (PTC):
- 0
- Voc:
- 0
- Vmp:
- 0
- Imp:
- 0
- Isc:
- 0
- Voc Temp (%/ºC):
- 0
- Pmax Temp (%/ºC):
- 0
- Isc Temp (%/ºC):
- 0
Inverter Specs
- # of MPPT Channels:
- 0
- MPPT Voltage Low:
- 0
- MPPT Voltage High:
- 0
- MPPT Voltage Maximum:
- 0
- MPPT #1 Amperage:
- 0
- MPPT #2 Amperage:
- 0
- MPPT #3 Amperage:
- 0
- Max MPPT #1 Wattage:
- 0
- Max MPPT #2 Wattage:
- 0
- Max MPPT #3 Wattage:
- 0
- Total Maximum Wattage:
- 0
The report appears here and updates live once everything on the left is selected. You can fine-tune exact panel or string counts per MPPT using the Trial Configuration fields in the report.
Output Report
Disclaimer and Terms of Use
This rebuilt String Sizer is provided “as is” for informational purposes only, without any presumption of accuracy. Auto-filled climate values are estimates from historical weather data and must be verified. String configurations must be confirmed by a licensed solar professional and approved by all authorities having jurisdiction. Always verify against the official EG4 documentation and the equipment datasheets.