Zwy
Emperor Of Solar
I did not see Victron contest the answer.
Multi-String High voltage MPPT with communication for large / multiple battery banks.
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Zwy
Emperor Of Solar
It's Victron's site, they could easily address the question and answer if it was incorrect or remove the post.
Sounds like "implied consent".
Hedges
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OK, we'll assume (the safer assumption) it is not isolated in any way, and if FETs fail shorted it will connect PV+ to output. When BMS opens, BMS FETs will fail, shorting PV+ to cells, which will overcharge, bloat, vent.
"Got a light?"
"Got a light?"
Zwy
Emperor Of Solar
Instead of one bashing one product against the other, it might be wiser to address the original post.
How it evolved into Blue Euro Trash against EG4 China/Taiwan Trash is beyond me.........
How it evolved into Blue Euro Trash against EG4 China/Taiwan Trash is beyond me.........
Zwy
Emperor Of Solar
Is the EG4 FET based? You are making ass umptions.
Can't answer? I can't find what it is. Maybe @Markus_EG4 can answer the question on whether the EG4 is isolated or FET based.
Brucey
Solar Wizard
Victron has fans too.
EG4 consumes nothing when it isn't running. I'll wager the Victron does not shut down when PV input drops to 0 as it runs communication which will draw power. The EG4 does shut down.
If you're concerned about it taking 25W when running with 5000W PV input, you have some serious issues.
With the fans running on the Victron, what is the self consumption? I can assure you it isn't 15mA.
The 2 Victron MPPTS are isolated from each other, the EG4 only has one MPPT. You're kinda stretching things there.
Maybe you need to read this concerning Victron MPPT's. https://community.victronenergy.com/questions/25541/isolation-of-mppt-solar-chargers.html
The idea behind a stand alone SCC for the intended purpose of this thread is to simply charge batteries and provide power on the DC bus of the system.
We don't know if the Victron is higher quality or not. You are assuming it is. It might be the same quality, after all, the Victron mentioned is built in India.
Time will be the judge on whether the quality of either unit is superior to the other.
That's not the isolation being referred to.
You have to understand the Victron rs450 has isolation features that are different from its 250/150V smart/blue solar sccs.
That referenced thread means nothing.
Brucey
Solar Wizard
Now if you need max safety and ul compliance something like a midnite solar SCC with RSD and arc fault detection would be the better choice.
Like a Barcelona 600/200 with dual trackers ?
fmeili1
Solar Enthusiast
Mhh, is that in your opinion a realistic scenario which could really happen? Do you have examples that this happened? In this post you've mentioned that there is a thread which discusses these scenarios - I was not able to find it. Do you have a link?
It would be a huge problem to have a potential risk to destroy all batteries (often >$20k of value) because just one FET in a not isolated AIO may fail.
In this post you've mentioned that a SPD would not help in this situation. Is your assumption that the battery breakers (the breakers between the inverters and the battery bank busbars and not the breakers inside the batteries like e.g. EG4-LL) are too slow to trip before the BMS and the cells get fried if the SPD would be connected between the battery and the (external) battery breakers?
I already have installed two 600Amp DC disconnect contactors (NO) between my two battery racks and the pos busbar for emergency shutdown reasons (e.g. smoke detector triggered or emergency button pushed, etc.). So it would be possible for me to measure the voltage on the battery busbars and disconnect these contactors in case of a high voltage event. Do you think that would work or would the time to release the contactors anyway be too long to save the FET's inside the BMS's?
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Hedges
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I didn't find the thread with a quick search either.
Likely scenario. FETs fail, often shorted.
The "isolation" I'm referring to is galvanic isolation between SCC PV+ input and battery+ output.
Basic architecture is buck converter, a FET and an inductor connecting those, plus a freewheel diode. Not galvanically isolated.
The other architecture uses transformer isolation for PV+. Even if PV- is hard wired to battery-. That I think keeps battery safe from this failure mode.
The manual for my SIC-40 addresses this risk, and calls for a disconnect mechanism. After much discussion, came to the realization that PV breaker can do it, needs remote trip mechanism.
A different approach would be crowbar PV. But that would present a drain or short to battery, given that SCC was bad. So I plan to use remote trip breaker.
Likely scenario. FETs fail, often shorted.
The "isolation" I'm referring to is galvanic isolation between SCC PV+ input and battery+ output.
Basic architecture is buck converter, a FET and an inductor connecting those, plus a freewheel diode. Not galvanically isolated.
The other architecture uses transformer isolation for PV+. Even if PV- is hard wired to battery-. That I think keeps battery safe from this failure mode.
The manual for my SIC-40 addresses this risk, and calls for a disconnect mechanism. After much discussion, came to the realization that PV breaker can do it, needs remote trip mechanism.
A different approach would be crowbar PV. But that would present a drain or short to battery, given that SCC was bad. So I plan to use remote trip breaker.
zanydroid
Solar Wizard
Aren’t most solar (outside of microinverter) MPPT / AIO non isolated in 2023?
Pushing hard for isolation to help protect 48V batteries seems hipster if 99% of products do not have it.
If UL allows non isolated in UL9540 ESS, is it ok to bury your head in sand and embrace it?
Pushing hard for isolation to help protect 48V batteries seems hipster if 99% of products do not have it.
If UL allows non isolated in UL9540 ESS, is it ok to bury your head in sand and embrace it?
Battery is inherently isolated due to HF step up transformer unless batt- and PV- are tied together internally. High voltage PV input AIO inverters have MPPT out connect direct to HVDC bus feeding non isolated DC-AC converter.
zanydroid
Solar Wizard
OK. Non isolated inverter doesn’t bother me that much. Both sides (PV and AC) are at comparable voltages anyway for safety considerations. EG if you have a 350VDC string, does it really matter that it’s not isolated from something that is 350V p-p (sure AC and DC have different human safety properties, as does pulsed DC)
FWIW the blocklevel schematic for SolArk and maybe a few others are floating around the forum. It shows which pieces are isolated. In case people on this thread were tempted to guess or worried about guessing, you can instead hunt for that picture and not guess.
There may be a NEC/UL requirement to keep the battery below 100V in wide range of conditions due to that being a threshold voltage for extra rules.
This is typical AIO high voltage PV input inverter topology. Solark probably is the same. @Solar Guppy can you confirm?
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Hedges
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Most GT PV inverters are now non-isolated transformerless. But some may have HF transformer.
Any AC coupled battery is likely galvanically isolated from grid; if not, it is their problem to manage.
If a hybrid has HV battery connected, again it is their problem. Could be a reason to require listed ESS.
The issue is SCC that is DC coupled to battery, typically 12V to 48V. The kind where you think about it having a BMS (or a lead-acid, they can get cooked in their own way.)
Any AC coupled battery is likely galvanically isolated from grid; if not, it is their problem to manage.
If a hybrid has HV battery connected, again it is their problem. Could be a reason to require listed ESS.
The issue is SCC that is DC coupled to battery, typically 12V to 48V. The kind where you think about it having a BMS (or a lead-acid, they can get cooked in their own way.)
fmeili1
Solar Enthusiast
This would save the batteries if such a fault happens. Do you know if these typical Voltronic AIO's clones like EG4-6500, MPPT6549, etc. have these HF step up transformers included? Maybe the EG4-6500EX is different because it has 2 additional DC-DC converters between SCC output and inverters DC bus to reduce the max. 500VDC to bus voltage.
They have to have them otherwise how else can they step up 48V to 200 - 400Vdc for the HVDC bus?
It probably has buck-boost MPPT converters since spec sheet states 90VDC - 450VDC MPPT range. Internal inverter DC bus voltage is likely 200Vdc.
zanydroid
Solar Wizard
Thanks for sharing. This isn't really typical in the sense that it only covers lower voltage PV strings (bottom left needs actively wrong text for 100-500VDC MPPTs removed, and changed to buck/boost), and it's very European. America exists too.
Zwy
Emperor Of Solar
EG4 MPPT 100-48V does #4 by a thing called a breaker. You know what that is, don't you? It's built right on the side of the unit. Once it trips, SCC will begin to shutdown.
#4 is just a wordy way of saying, "if there is a short, it will trip the breaker or disconnect".
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