MRI, errands, EpEver MPPT algorithm

errands

• got dog food. I normally buy 20# bags for storability but that aisle was slim. Bought a 50# bag and found a way to (hopefully) keep Muffin out of the storage.
• gas prices looked stable so I filled the tank. Dropped 10c the next day, of course.
• filled 1# propane bottles
• refilled 20# tank ($4.25/gallon), just under $18
• attended last scheduled VA apppointments (see below)

MRI complete

The thoracic spine, cervical spine, and brian MRI are complete. With any luck the results will be clear and communicated to my primary in a timely manner. Surely she will contact me in a timely manner to discuss. LOL.

I have two Amazon packages that will be here by the end of January so I’m emplaced here a while longer anyhow. See below.

EpEver MPPT controllers Achilles’ heel

I am a proponent of “horses for courses” approaches to problems. Find stuff that meets your needs and your budget. My power harvest is heavily biased toward solar, as recent calculations corroborated.

This dependence on solar makes my system highly sensitive to factors that affect solar harvest. I have tried to limit the effect of those negative factors:

• poor insolation - I overpaneled to meet needs during poor solar conditions
• I use MPPT controllers to handle overpaneling
• voltage sag - I chose a controller with voltage sensing

The 5414AN’s voltage sensing never worked as far as I can tell. I played “fudge the setpoints” and have come up with decent workarounds. I still would like to have accurage voltage sensing because charging voltages for lithium can be critical to solar-only charging.

the MPPT algo is not… robust

The MPPT algo works a treat under relatively-stable conditions: stable loads, clear weather. It’s slow and sometimes crashes under more challenging conditions.

slowness

If the system hsa been in stasis a while (as in float) and a large load is added it can take many minutes for the controller to find the new power point. So instead of running the load off the panel the load is run off the battery bank. Then the bank is recharged if there is enough time/light left in the day.

crashing to Vbatt+1v

Even worse, sometimes the system gets lost looking for the appropriate PP and sweeps the whole curve. Very….. slo-o-o-o-o-o-owly. As in “takes minutes” instead of the second or seconds other controllers take. In the worst (and very common) case the panels are run down to Vbatt+1v and the algo just sits there.

My panels are 30.3Vmp. If Vpanel is allowed to crash to, say, 14.5v then we are losing about half the power available. (W = V x I). This happens exactly at the worst time: when running heavy loads and/or during challenging insolation.

Turning the panels off and on again can often snap the controller out of its stupor. Sometimes it doesn’t and races to the bottom to sit at 14.x Vpanel again. In the winter when the sun is quite low, even under clear skies the algo can crash panel voltage and leave it there from ~3pm to sundown.

complaining to EpEver

Over the last year I have banged on EpEver’s twitter and youtube accounts, bringing this to their attention. They always say “email support to see what they can do for you”.

The problem is that it’s not limited to me; others report the same issue. It’s a firmware problem that engineers need to address. But fine, I finally sent the email as requested

my email

*Any thoughts on why EpEver controllers MPPT algorithms fall through and get stuck just above battery voltage? Right now my 30.3Vmp array is stuck running 14.5v:

https://img.mousetrap.net/2023/IMG_20230118_152627.jpg

This means it’s making about half the power it could be making and the controller is therefore unable to hold float.

There are many examples of this happening, including videos on Youtube. I have personally seen it happen on A, BN, and AN models. I’ve started collecting reports here:

https://rvwiki.mousetrap.net/doku.php?id=opinion:frater_secessus:epever#tracking_crashes*

EpEver support responds

*EPEVER Support support@epsolarpv.com via freshdesk.com

Jan 18, 2023, 8:45 PM (3 days ago)

to me Hi [redacted]

Sorry for the problem.

But all the MPPT controller has the find conditions.It is depending on the weather,cloud,connect wires,solar panel’s parameters,controller setting and shadow occlusion.

So if you met any problem please contact with us,we will try our best to help you.

Have a nice day!

Best Regards [redacted] EPEVER Support *

seriously?

I did contact with them and got this boilerplate BS.

I decided that if it happened again that day I’d do something about it. Behold, the MPPT algo crashed Vpanel to 14.5v and left it there below the battery voltage setpoint:

Here we are making ~12A in overcast conditions. If the algo were working it’d be about ~24A to support the bank. During a rare moment of functionality earlier in the day the clouds parted and I was briefly making 45A. Fine, I won’t rule out 50A.

pondering a solution

I really (really) don’t have excess cash right now, but I thought about trying to find a solution for ~$100. In this price range the fix would likely involve a non-EpEver MPPT in the 40A range. And preferably one with voltage sensing so I could stop playing voltage-offset reindeer games. I have 50A now but very rarely exceed 40A under normal condition, mainly due to the logistics of overpaneled systems.

Overpaneled systems start making usable power earlier, and bulk charging is typically complete well before local solar noon. So no big numbers are on display. Great for usability, lousy for winning “oh yueh, my system makes 4 million watts!!!!!!” d*cksize wars. Example: it’s 1043 as I write this sentence. The bank is at 88% SoC and I am running a small 100w crockpot to make lunch. The system is humming along at 30.2A.

i could not find anything with voltage sensing in this range. I gave serious consideration to the Renogy Rover 40A; it’s the ~same hardware¹ but there are no complaints about MPPT functionality with the Renogy firmware. Same for the SNRE/bouge/etc new crop of 40A. But none of these had voltage sensing.

a wild credit appears

I got a freakishly-large Amazon affilliate credit out of the blue, and have a bit of cashback credit there also. This meant I could expand my search a bit and still stay within the $100 cash outlay limit. Affilliate haul is usually ~$15/mo, enough to pay for hosting and domain name registration – not sure why this one was 12x that.

a wild used Victron appears

I am not a victron fanboi as many seem to be, but credit where it’s due. I have seen videos where the Vic’s MPPT algo was fast and resilient under challenging conditions.

Victron makes a 150|45 that’d be right, but at ~$400 it’s way out of my price range with no used units available. The 30A controllers are way too small for my array. The 100|50 was about $325 and there was a used one available for $240.

One of my complaints about Victron is they make things needlessly complex and expensive. Instead of having a voltage sense wire terminal you have to buy a $40 networked device to send that info to the controller. Same with load outputs. Fine, whatever. After the credit the controller + battery sense is <$100. The gear should be here by the end of the month.

controller shuffle

When the Vic comes in the 5415AN will be moved over to replace the existing 10A MPPT. The latter controller has been used for shore power charging and to run the 200w of portable panel. So if I ever use shore power I’ll get a boost and the panels can run free.

conclusion

I think EpEver is an excellent value in configurable MPPT where one or more of the following are true:

• power harvest is more mixed (not so dependant on solar as I am)
• loads are low and battery SoC is kept relatively high
• non-mission-critical applications

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1. both made by SRNE, I suspect ↩