Maximizing Solar for EcoFlow Solar Generators

The voltage limit for the DELTA Pro from step 1 is 150 volts, but you must account for Vocs increasing as temperatures drop. So if you live in a cold climate either use this conservative lookup table for the maximum Voc that your series stand can be or use the temperature corrected Voc calulculator to determine whether a setup will work with your solar generator. We will examine both methods below.

Conservative Lookup Table

Click this link and look at the appropriate column for your solar generator. The example below shows the Voc value to target for a DELTA Pro depending on the lowest temperature in your area.

Since I live in Illinois, I will choose -22°F, which means my Voc target is 124 volts. Taking the single panel Voc from step 2:

124 volts (array Voc limit) ÷ 37.1 volts Voc (single panel) = 3.34 solar panels

You can safely add three EcoFlow 400w Rigid solar panels in a series strand on a DELTA Pro. The actual Voc for the series strand will be:

37.1 volts Voc × 3 solar panels = 111.3 Voc

Temperature Corrected Voc Calculator

Click this link to use the calculator. In step 2 we decided on the EcoFlow 400w rigid panel so select it from one of the presets in the tool. For a third party solar panel, you can enter Voc and temperature coefficient found on the solar panel manufacturer's spec sheet.

Change the qualtity of panels from 1 to 2 to 3 to 4 and the table will change dynamically showing you what solar generators will work at what temperatures. At 3 solar panels in series (left), the DELTA Pro will work at all temperatures, but at 4 solar panels in series(right), the DELTA Pro will only work above 77°F. Any lower temperature will exceed the 150v limit and create black magic smoke.

Just like the Conservative Lookup Table technique, we arrive at three solar panels per series strand.

Ecoholics Solar Rule #4 is "In series, volts add" so the total specifications for this 3S1P strand is:

• 111.3 volts Voc
• 93.0 volts Vmp
• 13.79 amps Isc
• 12.9 amps Imp

which should achieve 1200 watts in full sun in perfect conditions with the panels angled properly.

Step 3 achieved 1200 watts with the addition of three solar panels to the DELTA Pro. The amps from step 3 is still below the 15 amp DELTA Pro specification so there is room to add more amps by adding more identical parallel strands. Adding another 3S strand to the existing 3S will bust way past the amperage specs of the DELTA Pro and overpanel the system into 3S2P like this:

Ecoholics Solar Rule #5 is "In parallel, amps add" so the total specifications for this 3S2P strand is:

• 111.3 volts Voc
• 93.0 volts Vmp
• 27.58 amps Isc
• 25.8 amps Imp

The DELTA Pro is rated at 15 amps while people have measured the DELTA Pro pulling 15.9 amps. The advantage of having these extra amps above DELTA Pro's capacity is to extend the number of hours in a day where the array can produce a full 1600 watts of power while the sun is not perfectly angled as well as improve rainy or cloudly day solar performance. Do not worry that we have exceeded the DELTA Pro's amperage specification. The DELTA Pro will pull what it needs just like an angle grinder or a cell phone charger both work fine from the same 120V household outlet. You will not break the DELTA Pro by adding more panels in parallel (you will if you add more in series). You can also add even more panels to go to 3P or 4P but doing so costs a lot of money for very little additional benefit.

PSA: Always double check your wiring by measuring the voltage at the XT-60i connector before plugging into your solar generator to make sure you do not exceed the maximum voltage determined in step 3.

Only you can decide whether doubling the price for panels is worth it to you. You can always buy some solar panels now and some later building up to the final array that you want.

Sometimes it might be beneficial to try different types of panels. The Temperature Corrected Voc Calculator enables you to play with some different approaches.

EcoFlow 100w Rigid Solar Panel

• Step 2: 20.3v Voc, 6.3a Isc
• Step 3: up to six panels in series
• Step 4: three parallel strands, 6S3P, 18 panels, 1800w or you could do more 6S4P for better cloudy day performance
• Pros: smaller size, easier to squeeze into tight spaces, easier to handle
• Cons: more cabling

EcoFlow 220w Bifacial Portable Solar Panel

• Step 2: 21.8v Voc, 13a (front) 8.8a (rear) Isc
• Step 3: up to five panels in series
• Step 4: since this is bifacial the front and back are already in parallel so you could choose to not add parallel strands
• Pros: fewer total panels
• Cons: unlikely to hit 1600 watts, portable panels don't last as long as rigid

3rd party 240w Rigid Solar Panel (what I have)

• Step 2: 37v Voc, 8a Isc
• Step 3: up to three panels in series
• Step 4: up to three parallel strands, 3S3P, 9 panels, 2160w
• Pros: extremely inexpensive as I got them used and locally (no shipping)
• Cons: needed one more strand of three panels than the usual DELTA Pro 3S2P configuration, thus 3-to-1 parallel adapters and inline fuses

Congrats, you've done your due diligence, figured out which solar panels to buy and how many to maximize your solar system. Even if you do not purchase all of the solar panels at once, going through this exercise will help plan your solar array so you don't end up starting over and jettisoning your first solar panels.