Series vs parallel panels for a power station

What each arrangement adds up

EcoFlow's 400 W rigid panel prints a Voc of 37.1 V and a short-circuit current (Isc) of 13.79 A. Put two of them in series and the voltages stack to 74.2 V. The current stays at 13.79 A. Put them in parallel and the voltage stays at 37.1 V while the currents stack to 27.58 A.

An article from the International Association of Electrical Inspectors states the same rule for larger arrays. Twelve 35 V modules in series give 420 V. Strings connected in parallel do not change the open-circuit voltage. A station's limits are therefore two separate tests, one on total volts and one on total amps.

Checking two panels against one set of limits

EcoFlow's DELTA 3 asks that the total Voc of the connected panels stay within 60 V. It prints 15 A as the current ceiling. Both arrangements of two 400 W rigid panels break one of those numbers. 74.2 V is over 60 V, and 27.58 A is over 15 A. One panel alone, at 37.1 V and 13.79 A, sits inside both.

A smaller panel changes the answer. EcoFlow's 160 W portable panel prints 21.4 V and 9.6 A. Two in series reach 42.8 V and 9.6 A. Two in parallel reach 21.4 V and 19.2 A. Three in series would reach 64.2 V, which is over 60 V.

How makers word the rule

The wording varies, so the right arrangement depends on the station. Anker's C2000 Gen 2 manual says panels must be in parallel. It also says total voltage must be 60 V or less, with a 17 A ceiling from 28 to 60 V.

Jackery's HomePower 3600 Pro Max manual describes one 500 W panel or three 200 W panels in series on each port. It labels its 16 to 60 V window a Vmp range, not an open-circuit range. A ceiling stated against Vmp leaves more room for Voc than one stated against Voc. Cold weather pushes Voc higher as well, as covered in why cold mornings raise panel voltage.

Two ports mean two sets of limits

Some stations spread the load over two solar ports, and each port keeps its own caps. The HomePower 3600 Pro Max lists 12 A on each of its two DC8020 ports. That doubles to 24 A and 1,200 W overall. A single string of panels faces the per-port number first. A second string on the other port faces its own.

Anker takes a different route on the C2000 Gen 2, with one XT60i input at 800 W. There the only question is whether all the panels, taken together, fit one set of limits.

Run the numbers before choosing

Multiply Voc by the number of panels in series. Then multiply Isc by the number of strings in parallel. Compare each result with the port's printed limits. The solar panel fit checker does this for any panel and station, including the cold-weather adjustment. It reports a match of printed numbers. That is separate from a maker's approval of any panel arrangement.