I have a Smartsolar 250/70 MPPT that is stuck on Off state that I cannot figure out. Perhaps someone has a suggestion that I can try.
It’s been working fine until a few days ago.
The MPPT show 0.0V Solar. I first thought it could be a blown fuse.
However if I disconnect the PV cables from the MPPT I measure 185V with my multimeter over the cables. All the fuses are fine, I swopped and bypassed breakers and they are also fine.
As soon as I connect the cable into the MPPT the voltage drop to zero. It is as if the MPPT shorts the PV.
What can be the problem?
Edit: I removed the BMS connection as well, but the same result.
Definitely a warranty claim. The input is shorted. Only the 250/100 has a relay that one can reset. All other models needs to go back for a RMA. Lost 3 MPPT’s with an unforeseen condition on one site last month. Exactly the same. Gave an alarm at first but after a power reset the alarm went away but inputs still shorted.
Lost another 2 250-70s on two other sites recently as well with the same issue. Stopped working a year after installation.
A customer bought equipment from me a few years back and did his own installation, as time went by he upgraded and expanded. We supplied and he installed. A while back he asked us to add a second inverter as he was not comfortable to do so and we did, while on site he decided to replaced an old 35A MPPT with a 70A MPPT as well as add a few more panels. My guys did as he asked, but did not go through the complete installation and all the wiring. All three MPPTs were feeding the battery through a 160 amp fuse. Adding more panels and upgrading the MPPT allowed for a higher current than the fuse rating to flow in this combined circuit. When the fuse decided it could not handle it anymore it did is job and “fused” leaving all of the MPPT’s under full production at that time with no place for the power to go. This is the part that I can not explain, as I dont have the knowledge to know exactly what happened at that moment. All three MPPT’s decided to short their inputs and never recovered from this event. I guess something similar as a DC ripple took place at that time and send some kind of transient through the MPPT’s that blue them. Partly it is my fault (or my guys fault) for only replacing the MPPT in the upgrade and not tracing the wires to see what is happening downstream. Assumption is the mother of all f%@#ups (As my history teacher use to say). Assuming that everything downstream is in order because the system was working like that before was the main reason for this mishap. The GX device was connected to the same side of that fuse and had to be replaced as well.
3 x MPPT’s and a GX was replaced at my expense? Lesson learned. Check all wiring on a self install if you get involved at a later stage.
A week before this, a client asked us to check his 5 star inverter as its not working anymore. His installer went bankrupt a while ago and he cant find any support. Jaco as always could not say no and went to site. Found the inverter in an off position and asked the client if I could switch it on. Yes sure. Switch it on and everything seemed fine, lifted the output breaker and “Bang”, all dead. Stupid Jaco, never checked, when inverter gave issues, someone decided to bypass the inverter in the Main db in the main house 20 meters from the garage where the inverter was installed in. When I switched on the Output breaker, I switched the output directly unto grid.
Jaco, please see that my inverter gets replaced, Jaco refuses to replace with a Fivestar and ended up replacing the system with a Victron system free of charge. 5kva Multi 11, Mppt and GX. Used his old Battery. Another expensive lesson learned.
Jaco tells his friend about this. His friend asks: Did this happen to you, or to the other Jaco… because this sounds like something that would happen to the other Jaco…
Reading what Jaco posted, I got goosebumps … who is this Jaco that Jaco is talking about in this reply to Jaco!? … no ways … this is way to close to “home” …
But serious now, one moment of not focusing … and it all goes south. I feel your pain.
Feedback time:
The MPPT has been checked by the Victron service centre and the PV inputs are latched. This happens more often these with lithium batteries. They suspect that the BMS disconnected upruptly during a large/full PV load, and then the MPPT fuse at the PV inputs. They also confirmed that the 250/100s has the relay latch that can be reset after this happens, but that this also does not last that very long.
It’s a sealed unit so not something you can repair, but rather replace.
And as my MPPT was older than the 5.5years for warrantee I now have to source a new MPPT unit
At least it did give me a very good service.
That is absolutely true, yes, the risk with just one battery and same port BMS.
The flip side to that, I make very sure I keep an eye on the cells, they will stay in line.
New feature for the Pylons, if added for all banks, DIY too, would mitigate that risk to close to zero.
So for me, the question is:
Do I manage the battery to ensure no BMS disconnects ever, avert a possible Ripple?
Or do I mitigate the Ripple issue, caused by imbalanced cells, we are supposed to control that, by compounding the amount of cells I need to manage, for no risk of a Ripple?
Better answer for me, ensure the bank behaves with as few connections and cells as possible.
If it becomes a issue in a few years due to age of the bank:
I get a better BMS with a bigger amp balancer.
Even better, the Pylon solution is by then commonly available on the Cerbo/Venus OS, where the system pulls back if a cell shoots out.
… will probably do both.
EDIT: So I just thought … are there anyone still out there what has just one bank?
So they would have the same challenge as I and everyone else with one bank/BMS, not so?
If you recall, way back then, when I understood what happened and why, the cause of it all, was also the time where I started advocating for checking the Delta, or in more refined terms (developer speak if you want), stop charging when a cell shoots out above a pre-set volt or as back then, if the Delta exceeds a preset value. Obviously the Venus has to be able to see the individual cell volts.
I’m sorry, I don’t follow. Let me formulate what I am saying a bit differently. I am saying that we learned (and by we I mean you) that when the DC bus is suddenly disconnected from the battery, the voltage spikes up, and that can damage things. We also know, that one of the advantages of multiple strings, is that if one string disconnects the others can remain connected, so the voltage can only spike up if all the strings let go. And third, we have also learned (and by we I again mean you) that it is better to have just one string? That seems like a contradiction.
OK, let me apologise publicly for being a bit of an ass there and getting on your case. And let me unemotionally state that is why I disagreed with you, on another thread, about going as big as possible with one string of the largest cells you can find. It is precisely because it makes the risk of of your entire DC bus going bye-bye bigger, with all the issues that entails.
I take the same position re other batteries. It is always better to have two smaller modules rather than one big module.
