Power supply into MPPT charge controller

[ericfx1984]

Hasn't been a lot of sun lately... So I've been unfortunately having to use generator more than I care to

In an effort to increase my efficiency I looked around to see what I had

I had some switching power supplies... They were 12 volt and adjustable so I put a pair of them together in series and adjusted them to about 26 volts

These are 30 amps so it would have been about 30 amps at 26 volts... Or about 780 Watts

I piped these into the solar panel connection on the MppT charge controller... Now this is a 60 amp unit

Additionally I have a 100 amp charger that is built into my inverter

I guess I should also mention that the entire setup is 4S

When I first started running it everything seemed to be working just fine I had about 55 amps hitting the battery at about 13.8 volts

After a little while this all changed... Basically as I was monitoring it on the app you would see the MPPT charge controller ramp up to about 55 amps of charge rate and then a few seconds later dropped down to about two or three amps Then a couple minutes later it would try to charge again ramping up to 55 amps and then drop back down to a couple amps

I decided to go down and see if anything was showing up on the display... I noticed that the red warning light would flash on the charge controller right before it would drop to a lower charge rate

And of course the next day when we had plenty of sun the charger seemed to work just fine

I even tried this on a couple other MPPT charge controllers that I had with similar results

 

[ericfx1984]

 

[Tomthumb62]

After a little while this all changed... Basically as I was monitoring it on the app you would see the MPPT charge controller ramp up to about 55 amps of charge rate and then a few seconds later dropped down to about two or three amps Then a couple minutes later it would try to charge again ramping up to 55 amps and then drop back down to a couple amps

Is this a question? What model is your MPPT?

My guess is the ramping up and down is the MPPT is trying to find the maximum power point. I don’t understand exactly how these MPPT algorithms work, but they are expecting a solar input, and the algorithm can’t understand the power supply you’ve given it.

Also, when I switched from a Renogy 30A MPPT to a Victron 30A MPPT, my power production, in similar conditions, improved 22%. Some have suggested that this could be due in part to the better MPPT algorithm of the Victron. The theory is it simply spends less time seeking the max power point and more time producing than cheap MPPTs.

 

[ericfx1984]

, when I switched from a Renogy 30A MPPT to a Victron 30A MPPT, my power production, in similar conditions, improved 22%. Some have suggested that this could be due in part to the better MPPT algorithm of the Victron. The theory is it simply spends less time seeking the max power point and more time producing than cheap MPPTs.

Yeah I have noticed some minor difference in production between my Victron 100/50 and my EP ever 60 amp

Certainly not 22% I would say less than 5% honestly

 

[AntronX]

Sounds like your power supply went into protection shutdown. Either overheating or something else.

 

[Tomthumb62]

Yeah I have noticed some minor difference in production between my Victron 100/50 and my EP ever 60 amp

Certainly not 22% I would say less than 5% honestly

Maybe the MPPT algorithm is better on the Epever than Renogy.

My % was certainly not a highly controlled scientific experiment. But I did measure 15% better production at one point and 30% another. Considering I couldn’t be sure the conditions were exactly the same, I split the difference at around 22%.

 

[ericfx1984]

Sounds like your power supply went into protection shutdown. Either overheating or something else.

That was my initial thought but when I hooked the voltmeter up to it absolutely nothing changed on the power supply voltage

 

[ericfx1984]

Maybe the MPPT algorithm is better on the Epever than Renogy.

My % was certainly not a highly controlled scientific experiment. But I did measure 15% better production at one point and 30% another. Considering I couldn’t be sure the conditions were exactly the same, I split the difference at around 22%.

Got you... I would definitely have to look at production over the course of at least a few days but preferably a few months to see the average... Of course all other variables would need to be the same

 

[MajicDiver]

My guess is the ramping up and down is the MPPT is trying to find the maximum power point.

If this is indeed what was happening, it’s a good reason for an inverter to have a feature to set the mppt to “dc source” where it does not search for the max power point. The Growatt MIN-TL-XH-US inverters some of us are using have a setting to do that with - I have not gotten around to actually using it to see if it works.

I have no idea how common it is for an inverter to have that feature- it’s not advertised for the MIN and is hidden in a higher level login in the app.

 

[pollenface]

I've been largely unsuccessful in running mppts from switching power supplies.

the mppt will pull the voltage down to 0v, let it go, then pull it down to 0v over and over again.

 

[ericfx1984]

I mean this guy is doing it and it seems to work for him

 

[ericfx1984]

I've been largely unsuccessful in running mppts from switching power supplies.

the mppt will pull the voltage down to 0v, let it go, then pull it down to 0v over and over again.

I may have to try it again... I didn't notice it pulling down to zero volts.. in fact I could swear that the input voltage didn't really change