EcoFlow’s DELTA 2 Max takes up to 1,000W of solar through two inputs, each rated 11-60V, 15A and 500W, according to EcoFlow’s U.S. spec page. EcoFlow says that’s enough to refill the 2,048Wh LiFePO4 battery in as little as 2.3 hours under ideal conditions. Those three numbers (voltage window, current limit and per-port wattage) decide which panels you can use and how to wire them. Below I go through each limit, show worked wiring examples with real EcoFlow panel specs, and estimate how much energy a day of sun really adds.
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Specs for the DELTA 2 Max and EcoFlow’s panels come from EcoFlow’s U.S. product pages. Daily harvest and charge times are my own estimates, and I’ve shown the math. You can check the current EcoFlow DELTA 2 Max listing on Amazon. On Oct. 17, 2026, EcoFlow’s U.S. store listed it at $1,049, down from a regular price of $1,299.
DELTA 2 Max Solar Input Specs at a Glance
| Spec | DELTA 2 Max (EcoFlow U.S.) |
|---|---|
| Solar inputs | 2 ports |
| Voltage range (each port) | 11-60V DC |
| Max current (each port) | 15A |
| Max power | 500W per port; 1,000W with both ports |
| Fastest solar recharge | As fast as 2.3 hours at 1,000W (EcoFlow) |
| MPPT efficiency | 99% (EcoFlow claim) |
| AC + solar together | Yes, X-Stream dual charging; solar priority settable in the app |
| AC charging | 1,800W, 15A max |
| Battery | 2,048Wh LiFePO4, 3,000 cycles to 80%+ capacity |
| Warranty | 5 years |
The Three Limits That Matter
1. Voltage: stay between 11V and 60V
Each port needs at least 11V to start charging and must never see more than 60V. The number to check on a panel’s label is its open-circuit voltage (Voc), not its working voltage (Vmp). Voc rises as temperature drops, so a string that reads 57V on a mild afternoon can go past 60V on a frosty morning. I plan for about 10-15% headroom, so I keep cold-weather Voc under roughly 54V. Our guide to solar panel specs explained walks through the temperature math.
2. Current: 15A per port
The controller will only draw up to its 15A limit. Even so, sizing each port so the panel’s short-circuit current (Isc) stays at or below 15A is the clean approach, and it avoids paying for panel output the station can’t use.
3. Power: 500W per port
Each input tops out at 500W, no matter how much panel you connect. Hanging 600W of panels on one port can still help on cloudy days and at low sun angles, but at noon you won’t see more than 500W from that port.
EcoFlow Panel Specs Used in the Examples
| Panel | Rated power | Voc / Vmp | Isc / Imp | Weight |
|---|---|---|---|---|
| EcoFlow 400W Portable | 400W | 48V / 41V | 11A / 9.8A | 12.3 lb (5.6 kg) |
| EcoFlow NextGen 220W Bifacial | 220W front / 175W rear | 21.5V / 18.4V | 12.4A / 11.9A (front) | 15.4 lb (7.0 kg) |
Sources: EcoFlow’s U.S. product pages for each panel. The 220W NextGen panel uses N-type TOPCon cells with a rated 25% efficiency and an IP68 rating, and it ships with an XT60i charging cable.
Worked Wiring Examples
Example 1: Two EcoFlow 400W panels, one per port
- Voltage: 48V Voc per panel. Even with a 12% cold-weather rise that’s about 54V, under 60V.
- Current: 11A Isc, under 15A.
- Power: 400W per port, under the 500W cap. Nameplate total is 800W.
- Don’t: put two 400W panels in series on one port. 96V Voc is well over the 60V limit.
This is the simplest high-output setup: one panel, one cable, one port, twice.
Example 2: Four EcoFlow 220W bifacial panels, two in series per port
- Voltage: 2 x 21.5V = 43V Voc per string (about 48V cold), under 60V.
- Current: 12.4A Isc (front side), under 15A.
- Power: 2 x 220W = 440W front-side rating per port, under 500W. Rear-side gain off light ground can push a string toward the 500W cap, but the controller limits it there.
- Don’t: run three 220W panels in series. 3 x 21.5V = 64.5V Voc is over 60V before you even account for cold.
For how much the rear side adds, see our explainer on bifacial vs monofacial solar panels.
Example 3: Generic 100W “12V” panels in 2S2P
Many 100W rigid panels are labeled around 22V Voc and 6A Isc. Always check your label, since these are typical figures, not a specific model. Two in series gives about 44V. Two of those series strings in parallel stays at 44V and doubles current to about 12A, so it’s 400W per port. With both ports you can run eight 100W panels for 800W nameplate, using a simple 2S2P harness on each port.
Example 4: One residential “400W” rigid panel per port
Household-size 400W panels are often in the high 30s to low 40s Voc, with Isc around 13-14A (again, check the label). One per port fits the window. Two in series would usually exceed 60V, and their large size makes them a better match for a fixed ground mount than for carrying around.
How Much Energy Does a Day of Sun Add?
Portable panels rarely hit their rating. Angle, heat, haze and cable losses usually trim real output to about 70-80% of nameplate. I use 75% and multiply by peak sun hours (PSH), which is the number of hours of full-strength sun equivalent your location gets.
| Array | 4 PSH (cloudier/winter) | 5 PSH (typical) | 6 PSH (sunny summer) |
|---|---|---|---|
| 400W (one port) | about 1,200Wh | about 1,500Wh | about 1,800Wh |
| 800W (2 x 400W) | about 2,400Wh | about 3,000Wh | about 3,600Wh |
| 880W (4 x 220W) | about 2,640Wh | about 3,300Wh | about 3,960Wh |
| 1,000W (max) | about 3,000Wh | about 3,750Wh | about 4,500Wh |
Math: array watts x 0.75 x PSH. With 2,048Wh of storage, an 800W array on a typical 5 PSH day can bring an empty DELTA 2 Max to full with energy to spare, and you can spend that extra running loads during the day. A single 400W panel covers roughly three-quarters of the battery on that same day.
Charge time example: at a real-world 600W from two 400W panels, 2,048Wh takes about 3.4 hours of strong sun (2,048 / 600). EcoFlow’s 2.3-hour figure assumes a full 1,000W of input.
Combining Solar with AC or Extra Batteries
EcoFlow’s X-Stream dual charging lets you take AC and solar at the same time, and the EcoFlow app can prioritize solar so the grid only fills in what the panels can’t. That’s useful for daily self-consumption, where you let the sun do the work and the wall outlet top up before evening.
The DELTA 2 Max also accepts up to two extra batteries for 6,144Wh total. Solar input stays the main unit’s 1,000W, so a bigger bank takes proportionally longer to refill from solar. With a full 6kWh stack, think of solar as a daily top-up rather than a same-day full recharge. For a size comparison with the newer models, see DELTA 3 Max vs DELTA 3 Max Plus vs DELTA 2 Max.
Setup Tips
- Match panels within a string. Series strings work best with identical panels. The two ports are separate inputs, so you can run different panel types on each one.
- Use the right cable. The NextGen 220W panel ships with an XT60i charging cable. For panels with MC4 leads, you’ll need an MC4-to-XT60 solar cable, plus MC4 extensions if you want the panels farther away.
- Tilt toward the sun. Re-aiming portable panels two or three times a day gets noticeably more energy than leaving them flat.
- Watch the app. Per-port input watts show right away whether one string is shaded or loose.
Planning a trip setup? Our portable solar panels for camping guide covers carrying weight and folding sizes, and Anker SOLIX F2000 vs EcoFlow DELTA 2 Max compares the DELTA 2 Max with its closest rival.
FAQ
What is the maximum solar input on the DELTA 2 Max?
1,000W total, made up of 500W per port across two ports. Each port accepts 11-60V and up to 15A.
Can I use just one solar port?
Yes. One port takes up to 500W, which is a good fit for a single 400W panel or a 2-series pair of 220W panels.
Can I connect two EcoFlow 400W panels in series?
No. Each has a 48V Voc, so two in series is about 96V, far above the 60V limit. Use one 400W panel per port instead.
How many EcoFlow 220W panels can I use?
Up to two in series per port (43V Voc), so four panels in total across both ports. Three in series (64.5V) is over the limit.
How long does the DELTA 2 Max take to charge from solar?
EcoFlow quotes as fast as 2.3 hours at the full 1,000W. With a more realistic 600W from two 400W panels, plan for about 3.5 hours of strong sun.
Can I charge from solar and AC at the same time?
Yes. EcoFlow calls this X-Stream AC + solar dual charging, and the app lets you set solar as the priority.
Do third-party panels work?
Yes, as long as each port’s string stays within 11-60V (cold Voc included) and you use an MC4-to-XT60 adapter cable. Size each string for 15A Isc or less and 500W or less.
Bottom Line
The DELTA 2 Max’s solar side is easy to plan once you know the 11-60V, 15A, 500W-per-port rules. One EcoFlow 400W panel per port, or two 220W bifacial panels in series per port, both fit cleanly and can refill the 2,048Wh battery in a single good day of sun. Check the current DELTA 2 Max price on Amazon, then size your panels using the examples above.
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