Zapper77
Renaissance Man (EG4 as of Jan 2025)
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C. doesn't work as a critical load panel. Edit that's where the disappointment comes in.
** UPDATE**Signature Solar Disappoints- Commissioned a 18Kpv still having issues
- Thread starter AZG
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ricardocello
Watching and Learning
You can also deduct any other active loads on the 18kpv, depending how close to zero-export you are,
so it's not necessarily as bad as that worst case I gave above.
But still, there is no easy way to know what you are using when a big load shuts off to guarantee coverage.
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robby
Electronic Engineer
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What do you mean by that?
JohnKl
We'll be right back
Very disappointed.
Zapper77
Renaissance Man (EG4 as of Jan 2025)
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See in the photo. C doesn't show UPS.
So anytime the Grid goes down and if you don't have batteries to consume excess solar or support the load when clouds crossover...you end up being disappointed. That is how I took James comment.
sunshine_eggo
Victron's little biatch
rogerheflin
Solar Enthusiast
I noticed that too. C has no "UPS" even though the text says a misleading EPS. I also do not see a way technically to make this viably work without a battery. Early in the morning/late evening with limited sun it will work like crap, any clouds again crap, a MPPT sweep crap, at best the load terminals will be flipping back and forth to grid. And while the inverter could predict the MPPT sweep and switch to grid, it cannot predict the clouds nor handle the early morning sun. I don't see a possible viable way to make it work OK when set to off-grid no matter what anyone does in the firmware (outside of staying on the grid the entire time and never using solar at all).
seneysolar
24V
His grid did not go down, and his inverter output is going off
rogerheflin
Solar Enthusiast
With off-grid when there is not enough solar for any reason it must switch back to grid. switching back to grid throws relays and drops all power for around 20ms and it is bad. On mine with a fully functional grid early in the morning (with the batteries off) it flipped the load terminals back and forth bad enough that it cleared my routers(it was not on a ups) settings from all of the reboots and mine was only doing this for 5-10 minutes before I bypassed it. There is NO WAY to code off-grid to work acceptably with less than reliable solar only (when using the UPS/load terminals), it will have to switch back to grid every time a cloud goes by, and will be unacceptable.
Gavin Stone
Solar Wizard
I just can’t picture this being a smooth transition from PV to grid without a battery. Especially with the inconsistency of the PV with clouds and morning/evening solar. If you’re gonna budget you could always try one rack battery to smooth over that transition time. But then you’d likely overload it.
Exactly. They said it would work, and it does work. It just won't be smooth when it has to flip back and forth.
If it could operate like a microinverter and stay totally synced up all the time, then it would be smooth. But that requires a proper interconnect agreement to allow max output at all times to backfeed. Maybe it does support that. But the OP is trying to not backfeed because of no interconnect agreement.
I'd NEVER recommend running it like that. If running without an interconnect, don't set it up where it can ever push back. Which necessarily means batteries.
If it could operate like a microinverter and stay totally synced up all the time, then it would be smooth. But that requires a proper interconnect agreement to allow max output at all times to backfeed. Maybe it does support that. But the OP is trying to not backfeed because of no interconnect agreement.
I'd NEVER recommend running it like that. If running without an interconnect, don't set it up where it can ever push back. Which necessarily means batteries.
Quattrohead
Emperor Of Solar
So we finally agree that the message was 100% correct but the delivery was a bit....blunt.
Watts247 has shown several video's of inverters running large loads from solar only, but his video's have never addressed what happens when the sun pops behind a cloud.
Watts247 has shown several video's of inverters running large loads from solar only, but his video's have never addressed what happens when the sun pops behind a cloud.
wpns
Solar Joules are catch and release
I've never been a fan of the 'balanced on a knife-edge' off-grid-without-batteries paradigm. Unless you are planning on supporting it (if it can even be supported) you should never put it in your marketing literature or let your customers even imagine it might be done. Or you'll end up <here>.
Yes. Content 100% accurate.
Delivery method could use some polish.
I think the marketing literature should show it, but with a huge asterisk saying "performance will be degraded at low sunlight levels and a simple, short paragraph about how a battery provides ballast for morning and evening sun, clouds, etc. Maybe market a higher C rate, lower capacity battery specifically for those who don't want to have a lot of battery but want to smooth out performance, have surge starts, somewhere to "dump" energy when a high draw item clicks off, etc. Maintain its SoC somewhere in the 80% range so it has reserve capacity on either direction for dumps and draws. Hey, look, I'm doing product design ideas, now give me commission lol.
Quattrohead
Emperor Of Solar
Technically speaking the documentation is completely correct, but it is just so subtle that.. who the hell is reading the damn documentation anyway. Hence my favorite saying that I'm not allowed to say anymore because I get thrown in the forum corner with stale bread and water.
Q-Dog
¯\_(ツ)_/¯
RTFM? It is one of my favorite sayings.
Gadwall*Drake
Solar Enthusiast
So it's the customer's fault for believing the marketing BS. Got it.
seneysolar
24V
All references to operation without a battery should be removed from the manual. Just because it happens to work sometimes does not make it a functional attribute.
jzampieron
Solar Enthusiast
tl;dr: You need a properly sized battery... full-stop.
Thoughts:
IDK how any inverter of serious size is going to work reasonable well at all without a battery of sufficient size.
You need the battery as an energy buffer to handle the variability in load output (surge) and solar inputs.
Without that you need to be drawing from the grid directly (i.e. AC-bypass). Even a traditional double-conversion UPS has a battery on the DC bus.
Getting the power control right to balance the grid-draw, grid-sell, DC to AC and DC-DC conversion spot on without that battery is just not going to happen reliably. There's too many transient conditions for the control loops to lockup properly and consistently.
It would have much too high a SWaPC to try to do that internally to the inverter with capacitors on the DC-bus. The caps just get you enough to let the battery kick in.
You might be able to get only grid-sell mode to work (i.e. no-loads).
I highly recommend folks study the MIT OCW 600 level Power Electronics course --
if you really want to understand how this stuff works. The instructor literally wrote the book on this.
Thoughts:
IDK how any inverter of serious size is going to work reasonable well at all without a battery of sufficient size.
You need the battery as an energy buffer to handle the variability in load output (surge) and solar inputs.
Without that you need to be drawing from the grid directly (i.e. AC-bypass). Even a traditional double-conversion UPS has a battery on the DC bus.
Getting the power control right to balance the grid-draw, grid-sell, DC to AC and DC-DC conversion spot on without that battery is just not going to happen reliably. There's too many transient conditions for the control loops to lockup properly and consistently.
It would have much too high a SWaPC to try to do that internally to the inverter with capacitors on the DC-bus. The caps just get you enough to let the battery kick in.
You might be able to get only grid-sell mode to work (i.e. no-loads).
I highly recommend folks study the MIT OCW 600 level Power Electronics course --
Not saying that. Just saying the marketing needs to be a lot clearer as to the limitations of various modes. But also, the way the OP is trying to use it is not kosher, and I believe that is probably making it more of an issue. If he had an interconnect agreement so he could backfeed then this blipping on and off would likely not be an issue.
My impression is he's really trying to use it in an unsupported method. To really implement batteryless solar support REQUIRES an interconnect agreement so that it is 100% in sync with the grid at all times. But he's not, hence the cutouts.
Quattrohead
Emperor Of Solar
100%
Gadwall*Drake
Solar Enthusiast
I was half joking, but only half. There should be some constructive help available from the manufacturer here, especially since they have multiple accounts here. I think the electrician should have been the one to figure this out, but of course I was not there either. This seems to be yet another example of a common thing I'm finding in the DIY renewable energy space: manufacturers and online sellers happy to supply product with limited or downright useless documentation and support. You pay your money and you take your chances.
I am very impressed with the forum, sorting this out for free while the people who should be doing it watch.
robbob2112
Doing more research, mosty harmless
Just going to throw this out there - might be simpler and better to get an interconnect agreement rather than depend on hope.
If you are also supplying your guest house that is just more areas which can cause backfeed. A dryer here, a furnace fan there, a heat pump or AC unit - when they turn off while running from inverter you will export.
Ya might have to bite the bullet and pay a fine with the permit application and fix anything they find wrong. And the PoCo may not be very happy at all.
Eventually they will get tired of the nonsense and send you the nasty letter and force you to do it anywy or pull the meter (or remote turn it off) and you will need batteries to turn on a light.
As for selling to DIY and having crappy docs - I think they assume the average person that is going to attempt DIY with something this complex is not suffering from the Dunning–Kruger effect.....
NOTE - I am not pointing at you - but there are many people that get in over their head before they call for help then don't understand the answers the tech support is trying to give... or tech support isn't giving good answers because the docs are so dodgy that unless they have run into this exact situation before they are stumped.
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rogerheflin
Solar Enthusiast
It should work as a pure grid-tied inverter (nothing connected to the load terminals). Anything on the load terminals will work like crap.
windsurfer
Solar Enthusiast
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It's not that complicated. It's just very poorly documented and marketed in a misleading manner.
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