This document issues a critical warning regarding the risks of exceeding the maximum input voltage (Voltage Open Circuit or VoC) when connecting solar panels in series to EcoFlow power stations, emphasizing the significant voltage increase that occurs in cold temperatures. The text highlights a common configuration error (four 400W panels in series on a Delta Pro) that appears safe at standard temperatures but is highly likely to destroy the MPPT controller when cold. To prevent damage, essential rules for solar array sizing are provided, stressing the need to stay "way below" the voltage maximums. Comprehensive tables detail the temperature-corrected VoC limits for various EcoFlow Delta and River series models down to -40Β°C, and practical examples demonstrate how to calculate safe series configurations based on location and specific panel specifications.
Sizing Solar Arrays for EcoFlow Devices: Avoiding Cold Weather Over-Voltage
Initial Warning (DO NOT DO THIS): A common mistake is connecting four 400W solar panels (37.1V VoC each) in series to a Delta Pro. At $25^{\circ}C$ ($77^{\circ}F$), the VoC is 148.4V, which is just under the 150V limit.
Key Takeaway: This seemingly safe setup will cause damage ("black magic smoke") in cold weather because panel voltages increase as temperatures drop.
The Golden Rules for Solar Sizing:
Stay below the maximum voltage specs of the solar generator.
Stay way below the maximum voltage specs when it gets cold.
Note on Series/Parallel: Volts add in series; amps add in parallel. Exceeding amperage specs is acceptable, but voltage is a hard limit.
Delta Series VoC Maximums: The maximum acceptable VoC decreases significantly with temperature.
Example Detail: For the Delta Pro, the 150V limit at $25^{\circ}C$ drops to 136.4V at $0^{\circ}C$ ($32^{\circ}F$), and further decreases to 120V at $-40^{\circ}C$ ($-40^{\circ}F$).
River Series VoC Maximums: Similar temperature corrections are required for River models.
Example Detail: The maximum for the River 2 Pro drops from 50V at $25^{\circ}C$ to 40V at $-40^{\circ}C$.
Example 1: Delta Pro in Georgia (Mild Climate):
Using $0^{\circ}C$ ($32^{\circ}F$) as the conservative low temperature, the VoC limit for the Delta Pro is 136.4V.
EcoFlow 400W panels have a VoC of 48.0V.
Calculation: Only two panels (96V total) can be safely connected in series; three panels would exceed the safe limit.
Example 2: Delta 2 Max in Canada (Cold Climate):
Using $-40^{\circ}C$ ($-40^{\circ}F$) as the expected low temperature, the VoC limit for the Delta 2 Max is 48.0V.
EcoFlow 220W panels have a VoC of 21.8V.
Calculation: Two panels (43.6V total) can be safely connected in series. Since the Delta 2 Max has two input ports, the user can run two parallel strands of two panels each (four panels total).
Source Credit: The provided correction factor tables are adapted from the National Electrical Code Handbook (Table 690.7(a)).