Solar panels for a power station: pairing basics (voltage, current and watts)

Match three numbers and you can't go far wrong. The panels' open-circuit voltage (Voc) must stay under the station's maximum solar input voltage, their current must stay under its current limit, and their watts should be close to the station's solar rating. Series wiring adds the voltages, parallel adds the currents, and cold mornings push the voltage up.

The worked example uses specs from EcoFlow's 220W bifacial panel manual and the DELTA 3 Plus's Australian spec page, and the other station limits come from Bluetti and Jackery. All are linked at the bottom.

The three numbers on a panel

Every panel has a label or manual with its open-circuit voltage (Voc), short-circuit current (Isc) and rated watts. EcoFlow's 220W bifacial panel, for example, lists a Voc of 21.5V and an Isc of 12.4A from the front face, according to its manual.

Voc is the voltage with nothing connected, which is the highest the panel will produce. That's the figure to check against the station's limit. Isc is the most current it can push. Rated watts are measured at a standard cell temperature of 25°C, which an Australian panel in full sun rarely sees.

Series and parallel, worked out

On the DELTA 3 Plus, EcoFlow lists each of the two solar inputs at 11 to 60V and up to 500W, with total Voc no higher than 60V and Isc no higher than 15A. Here's how the 220W panel fits:

So two panels in series on each input is the way to wire four of them, for 880W of panels across the two inputs. The Bluetti Elite 100 V2 gives you a bit more room: Bluetti lists its input at 12 to 60V and up to 20A, which still rules out two of these panels in parallel (24.8A) but suits panels with a lower current.

The Jackery Explorer 1000 v2 works differently. Jackery lists two DC8020 inputs at 16 to 60V and 200W each, so you'd run one panel per input rather than linking them.

Cold raises voltage, heat cuts power

Panel voltage goes up as the cells get colder. EcoFlow's manual gives the 220W panel a Voc temperature coefficient of minus 0.25% per °C, which means each degree below 25°C adds 0.25%. On a 5°C winter morning that's 20 degrees colder and 5% more voltage: two panels in series go from 43V to about 45V. Still fine under 60V, but a string that sits right at the limit on paper can go over on a frosty morning in the Granite Belt or the high country.

Heat works the other way and costs you power. The same panel loses 0.30% of its output per °C above 25°C, according to EcoFlow, and SolarQuotes notes that panels in Australian sun commonly run 20°C or more hotter than the air. A panel at 65°C is 40 degrees over, which takes about 12% off: a 220W panel tops out around 194W before you count angle, dust or shade.

How long a refill takes

Take the four-panel DELTA 3 Plus setup (880W of panels). Knock 12% off for heat and a bit more for angle and cable losses, and you might see 650 to 700W in the middle of a clear day. A 1,024Wh battery would refill in about an hour and a half of that, but you only get peak output for a few hours around noon. Morning and afternoon sun gives much less.

A smaller setup changes the picture. A single 220W panel giving about 180W in good sun takes six hours or so of strong light to put 1,024Wh back. That's a full day for one battery, which is why our caravan sizing guide suggests 400 to 500W of panels for a 1kWh station on a long trip. In a storm blackout, when the sky's grey, expect a fraction of the rating. Our blackout and cyclone guide has the rest of the plan.

Connectors and cables

Brands use different plugs. EcoFlow and Bluetti use XT60-style inputs and Jackery uses DC8020, while most panels have MC4 connectors. Bluetti's manual notes the MC4 to XT60 solar cable isn't included with the Elite 100 V2. Adapters exist for mixing brands, but the voltage and current limits still apply, and a cheap adapter is a weak point in the circuit. Use the maker's cables where you can.

Safety with panels in the sun

Two panels in series make more than 40V DC, so keep connectors dry, don't disconnect under load if the manual says not to, and keep leads out of walkways. Plug panels only into the station's solar input.

Keep the station itself in the shade, even while the panels are in the sun. EcoFlow gives the DELTA 3 Plus a charging range of 0 to 45°C and Bluetti gives the Elite 100 V2 0 to 40°C, and a black box on a ute tray in January goes well past that. The Queensland Fire Department says not to charge a lithium-ion battery that's hot or damaged, and to charge on a hard surface with good ventilation. If you're still choosing a station, our EcoFlow vs Bluetti vs Anker SOLIX comparison compares their solar inputs.

Where to buy in Australia

Buying from the brand's Australian store means 230V AU outlets, the local warranty and local support. Prices move around a lot, so check on the day.

• EcoFlow DELTA 3 Plus (2 × 500W solar inputs)EcoFlow AustraliaSee it at EcoFlow Australia
• Bluetti Elite 100 V2 (1,000W solar input)Bluetti AustraliaSee it at Bluetti Australia
• Bluetti solar panelsBluetti AustraliaSee it at Bluetti Australia