EcoFlow Delta PRO deep-dive review

_MPPT Controller_

The MPPT controller in the Kickstarter version (and now retail one) had it’s power capacity upgraded from 1.200W to 1.600W by increasing input amps from 12A to 15A although I’ve seen it go as high as 16A (VIDEO 15.5A) as reported by the DeltaPRO’s internal data and my external meter which makes me wonder if that was a glitch of some sort or in specific cases it can pull > 15A…?

The mppt controller reported IN watts readings are similar to my external measurements which is a very good thing. 🙂

It needs around 13W/m2 of ambient light with my 2 arrays of big panels to latch on and start producing some Watts. The lowest I’ve seen as reported by my external metering is around 12W before disconnection.

Users of the DeltaPRO will notice a constant clicking sound at sun up /down that can be annoying and give the impression that something is going to break inside the DeltaPRO; when the MPPT controller senses a voltage that is > 11V (under an internal small mA test load), it will engage the main circuit which has a (variable) minimum load that cannot be sustained by the panels (because of low ambient light conditions) which in turn brings down the voltage low enough to make it collapse and disengage the main circuit.

The controller will repeat this cycle until the panels can produce enough amps without dropping the voltage below minima (what I call “latched on”) or the voltage that the panels produce is below 11V so the controller will not try to engage the main circuit.

For now I’ve chosen to manually flip the contact breaker when I’m nearby and hear the clicking sound or use the hack that I discovered while playing with the app where one can remotely disengage the MPPT controller by going to settings and choosing a charge level that is below the current level in the “Discharge/Charge Level“.
This is not an elegant solution nor it’s intended purpose but it works just fine for my case when I’m not at home.

Usage Example:

When you see 0W input reported in the app it means that what the MPPT controller sees as input is < 40W so you go to settings -> Discharge/Charge Level = ? – 50%. This will immediately disengage the MPPT controller (but also AC charging) if the DeltaPRO’s charge level is > 50%. Later you can change it back again to your usual setting.
I wish Ecoflow will give us a in-app toggle to enable/disable mppt circuitry and also an option to program the hours when to engage/disengage it.
I would also like for Ecoflow to decouple this setting from actually turning off the mppt controller so you could actually NOT charge the battery but still provide energy from PV to power whatever loads are hooked to the DeltaPRO .

The MPPT controller has a (FW?) glitch (?) where it will report 0 IN Watts for anything below 40W but will show the OUT Watts as low as 12W that the DeltaPRO will use internally to offset some of the drain on the battery from running it’s own electronics.

Be aware that anything below 120W has absolutely horrendous conversion efficiency where you will loose around 25%+ plus what the DeltaPRO consumes which could be up to 55W if you’re using AC inverter so in the end that 120W transforms to a meager 35W that can be used to charge battery or power some tiny AC load.

I’ve observed that the minimum LCD INPUT reading (via MPPT with FW=.60/.68/.71):

• To cover the DeltaPRO’s internal consumption with inverter ON is around 80W (as seen on LCD)
  So this means that when you see that your MPPT controller is reporting around 80W, the net balance is -0W from battery when you have AC ON (inverter) and no load. You can guess this by checking the time left on battery is not going down and the charge circle is not turning.
  
  
• To cover the DeltaPRO’s internal consumption with inverter ON + start charging the DeltaPRO around 120W (as seen on LCD)
  A quick way to know how much LCD INPUT you would need from the MPPT controller to start charging the battery when AC is engaged with some load is to look at the OUTPUT and add 120W to the number.
  Ex: Inverter ON with an OUTPUT LCD (reported load) of 150W will require the MPPT controller to report INPUT LCD of around 270W for the charging circle to start spinning.

Anything above 600W will trigger the fans to come on at mid (FAN=2) and above 900W to high (FAN=3 61db) speed which can be annoying when there’s no need for such extreme cooling when the temperature of MPPT is < 50c and AC is < 30c as reported by DeltaPRO’s internal data.

Also of note is that the maximum usable power from mppt/solar is not 1.600W but something close to 1.450W as you will loose around 150W from the mppt controller conversion efficiency and running DeltaPRO’s internal electronics. Any AC load around 1.450W and you’ll be pulling energy from the battery.

After multiple tests I came to the conclusion that the most efficient (& cost optimized) way to charge the battery with < 200W (MPPT) is to turn off the AC/inverter & unplug everything that you have plugged in the DeltaPRO (or ATS in my case); you’ll be able to start charging with less than 40W (but this will take a very very long time) reported by DeltaPRO and I’ve seen instances where the battery is charging with as low as 20W internal (means 20W as reported internally by the BMS).

I only use this approach when there’s very bad weather, the battery is running low and I don’t know if the weather will improve so I turn off DeltaPRO’s AC and the ATS (Automatic Transfer Switch) flips automatically to the electrical company.
Of course I can also do this remotely via app without any issues and once I see that the panels are producing enough Watts to sustain the room & charge the battery at the same time, I turn on the DeltaPRO’s AC which in turn flips the ATS over to the DeltaPRO.

I have to report a recurring bug where the MPPT controller will completely collapse when the battery is 100% charged (battery flow = 0W), the DeltaPRO is powering AC loads and you increase the load; mppt will go all crazy high amps which in turn collapses the PV arrays and then the mppt controller has to start from 19V with very low watts inching slowly up on volts and watts until it reaches the balance point which is 125V (for my PV setup).

The mppt controller will pull extra energy from the battery until it reaches the balance point at which point it will start topping off the battery. You end up in a vicious cycle where this buggy behavior is repeated over and over again. Thankfully the LFP battery can take the constant abuse but it is a very frustrating bug that needs urgent fixing.

How can I put it lightly…. in it’s current state (FW .68/.71) for my setup the MPPT controller is a complete mess.

In a system that is running 24/7 and depends on limited hours of sun to recharge the battery and power the house, one cannot afford to have a half baked MPPT controller with an unreliable behavior that is constantly going out of bounds, dropping the ball and then having to scan over and over again from very low voltage up to the correct optimum voltage, if it ever manages to find it, as this constantly drains the battery and then tops it again in an endless cycle. Worse is when the MPPT controller refuses to go above 1.285W for some strange reason; I’ve noticed the mppt controller will obsessively lock itself below 10A while letting the voltage rise as high as 144V (ex:144V*8,9A). This is extremely frustrating on bad weather days when you get a short break in the clouds with high solar irradiation and a broken mppt controller that refuses to harvest the extra power.

What worries me even more is when I’m powering high AC loads (ex:1.400W) with a buggy mppt controller locking itself to a max of 1.285W which forces the DeltaPRO to pull the rest from battery when there’s plenty of sun to max out 1.600W.

The icing on the cake is when the MPPT has a moody day where it will stay even lower than 1.285W and start draining the battery to power the load when outside we are reaching 900W/m2; I disconnect and reconnect both PV arrays via breaker and for a few seconds I see the holy grail of 1.600W and > 10A for the mppt controller to decide that it is too much, drop down again, start draining the battery and after a few more seconds, completely crash and start all over again, climbing slowly from 30-40V (very low watts) all the way up to 120V+ for it to lock itself again at a max of 1.285W and voltage again to 144V…
I’ve tried all possible combinations of PV arrays; with both arrays together as with a single array, one by one and I can reproduce the same issue over and over again.

I’ve also have come across some weird behavior where the reported MPPT temperature is > 98c when fans were blowing at full speed (FAN=3) and nowhere near max watts while other times the controller is < 85c in similar conditions…?
For those wondering, the room ambient temperature was below 20c so it shouldn’t be an overheating issue and all 4 fans were engaged and producing high airflow without obstructions.

It seems that my DeltaPRO can reach 1.619W only an only when mppt controller temperature is < 80c. If it reaches 80c and above then it will instantly drop from 1.619W to 1.285W and stay there forever.
If this proves to be true, it would mean that the normal/guaranteed power was the original 1.200W and anything above is a “turbo” mode only when temperature allows for it. (or maybe my unit is broken?).
Today (28/03/22) I managed to make it stick at 1.6KW (efficiency 92%) for a few minutes (with 510W/m2 @ 11am) and it was > 90C, with a max of 104C, so it is not temperature bound. I think the MPPT algorithms need improvements in correctly tracking my PV setup as maybe it is too powerful? Everything is great if it manages to stay below 127 volts; once it goes above 126 volts, it looses the tracking and reverts to 1.285W and stays there forever.

I hope Ecoflow engineers read this and clarify what is going on.

I’m convinced that this can be fixed by tweaking/improving the mppt tracking algorithms to behave as intended and hope that once Ecoflow are made aware of the issues they will fix it quickly.

I would like to suggest maybe adding the possibility of inputting some parameters to help the mppt tracking algorithm choose the best voltage which in my specific case is 126V (anything higher than 126V means you’re wasting power = the PV arrays are generating more power than you are taking from them).
As always, I’m more than happy to help Ecoflow in any way possible.