Can EG4 18KPV work as UPS for sensitive loads like computer servers?

[Samsonite801]

10 to 12 kW of 240VAC is what we need for the two servers. This is not a typo. We have a generator so the 18KPV only needs to last long enough for it to start. If we had APC UPS as you suggest then we wouldn't need the 18KPV! If the 18KPV is not suitable as a UPS for a server then it shouldn't be marketed as one. Many users might be having power quality problems during the 18KPV switch-over and not know it. Or maybe it is only us due to this one unit, our configuration or something else we are doing wrong. This is why I am asking for feedback from 18KPV users. Would also like to hear from Sol-Ark users if they are powering sensitive critical loads like computers as maybe they work better/different. The Sol-Ark does quote a 5ms switch over vs 10ms EG4. I wonder if one number is too simplistic for this spec. Is there actually a "curve" involved where it takes time to ramp up the inverter and this spec should either show this curve or provide a couple of data points to show current availability vs time. Total speculation on my part here.

You could always consider configuring your 18k to work like an 'On-line' UPS, which would be where you leave the 18k to run only on battery all the time, and buy enough standalone DC chargers (for example the EG4 Chargeverters), where the generator (or grid) can just keep the batteries charged 100% of the time via the standalone chargers. Then there is no switchover from the server rack's perspective.

Just install an ATS upstream of the standalone battery chargers, to automatically switch between the grid and generator power.

I might rather do that anyways, since the standalone chargers can tolerate a wider range of input frequency in case the generator frequency is not held perfect for some reason, the 18k inverter/charger would reject the power, where the standalone charger would keep going.

Chargeverter advertises an input frequency of 50-60Hz. I have 4 AIMS 18.75a chargers which advertise input frequency tolerance of 40-70Hz, so something like those can take dirty power all day and still charge batteries like normal, business as usual, even if the generator governor is failing to hold RPM steady.

Just a thought anyways.

 

[Ampster]

so something like those can take dirty power all day and still charge batteries like normal, business as usual, even if the generator governor is failing to hold RPM steady.

Yes, HiTechLab just posted a video where he used quite a few Chargeverters and also acquired a bigger generator so it would only have to run a few hours each day instead of his old generator which kept being knocked off the connection to his SolArks because of the dirty power from the old generator. I think the bigger generator was not much cleaner but the Chargeverters were able to convert that to D.C without issue

 

[Samsonite801]

Yes, HiTechLab just posted a video where he used quite a few Chargeverters and also acquired a bigger generator so it would only have to run a few hours each day instead of his old generator which kept being knocked off the connection to his SolArks because of the dirty power from the old generator. I think the bigger generator was not much cleaner but the Chargeverters were able to convert that to D.C without issue

Yeah that was cool, lots of power there...

Reference:

 

[PConlin]

We had a very brief brownout today when the office UPS batteries "clicked" and the the overhead lights flickered as utility power wavered. This was very brief but enough for the office UPSes to switch to battery then switch back to utility almost instantly. The office computers never noticed as they got sufficient power from their UPS battery. Our server powered directly by the EG4, however, went down and rebooted. The log in the EG4 shows no such event. It didn't notice a utility power glitch long enough to reboot a computer! This is worrying.

Is anyone using the grid-to-battery relay in their EG4 to provide power to computers? Not just servers but any office computer. Does your EG4 switch to battery for brief brown-outs? For those that don't trust the power from the EG4 and have separate UPS batteries between the EG4 and their office computers, do these office UPS units click/beep when the utility power power flickers? If they did this would imply the EG4 didn't switch and/or didn't provide backup power fast enough. This type behavior is what we are seeing with the EG4. Is this typical for an EG4?

 

[SignatureSolarJames]

We had a very brief brownout today when the office UPS batteries "clicked" and the the overhead lights flickered as utility power wavered. This was very brief but enough for the office UPSes to switch to battery then switch back to utility almost instantly. The office computers never noticed as they got sufficient power from their UPS battery. Our server powered directly by the EG4, however, went down and rebooted. The log in the EG4 shows no such event. It didn't notice a utility power glitch long enough to reboot a computer! This is worrying.

Is anyone using the grid-to-battery relay in their EG4 to provide power to computers? Not just servers but any office computer. Does your EG4 switch to battery for brief brown-outs? For those that don't trust the power from the EG4 and have separate UPS batteries between the EG4 and their office computers, do these office UPS units click/beep when the utility power power flickers? If they did this would imply the EG4 didn't switch and/or didn't provide backup power fast enough. This type behavior is what we are seeing with the EG4. Is this typical for an EG4?

what unit did you have? 18k?

 

[DIYrich]

We had a very brief brownout today when the office UPS batteries "clicked" and the the overhead lights flickered as utility power wavered. This was very brief but enough for the office UPSes to switch to battery then switch back to utility almost instantly. The office computers never noticed as they got sufficient power from their UPS battery. Our server powered directly by the EG4, however, went down and rebooted. The log in the EG4 shows no such event. It didn't notice a utility power glitch long enough to reboot a computer! This is worrying.

Is anyone using the grid-to-battery relay in their EG4 to provide power to computers? Not just servers but any office computer. Does your EG4 switch to battery for brief brown-outs? For those that don't trust the power from the EG4 and have separate UPS batteries between the EG4 and their office computers, do these office UPS units click/beep when the utility power power flickers? If they did this would imply the EG4 didn't switch and/or didn't provide backup power fast enough. This type behavior is what we are seeing with the EG4. Is this typical for an EG4?

I have a Sol-Ark 15k, and a few times a week, it will go off-grid for less than a few seconds, and I can't see anything in the logs. I'm guessing a momentary glich in the grid, and it goes off-grid. My electronics don't notice anything. I'm thinking about getting Solar Assistant to see what the Sol-Ark is seeing.

Also, per UL1741 SA, the inverter HAS TO stay on-grid between 88-120% (or 105.6-144v for 120v). A UPS can have a tighter range.

 

[rhino]

The Midnite Rosie inverter has 0ms transfer time because it always stays in sync with the grid. You'd have to parallel multiple for your load rating.

 

[PConlin]

what unit did you have? 18k?

18KPV. This entire thread about our 18KPV and how it is having problems switching from grid to battery.

 

[PConlin]

The Midnite Rosie inverter has 0ms transfer time because it always stays in sync with the grid. You'd have to parallel multiple for your load rating.

Thanks for contributing. Is the Midnite Rosie inverter doing double conversion to make this work?

 

[cs1234]

The Midnite Rosie inverter has 0ms transfer time because it always stays in sync with the grid. You'd have to parallel multiple for your load rating.

I remember seeing you say you were working on paralleling them. Did you get them working in parallel yet? If so, maximum number?

 

[rhino]

I remember seeing you say you were working on paralleling them. Did you get them working in parallel yet? If so, maximum number?

I do not have one since plans changed but had asked if they were able to be paralleled now (since originally they were not) and was told that that is now possible.

 

[DIYrich]

Thanks for contributing. Is the Midnite Rosie inverter doing double conversion to make this work?

How long does it take to disconnect the relay is the question. During that time, the grid will sink the power, and for all practical purposes, 0v will be received by your load.

"Zero transfer time - Rosie is always connected to your loads and the grid is paralleled into the system with a relay"

MidNite Solar Rosie 7048RE 7kW Hybrid Inverter

MidNite’s Rosie is a 7kW hybrid inverter and 48V battery charger with intelligent customizable grid connection features and incredible 20kW surge capacity.

www.altestore.com

 

[rhino]

Would need someone with more knowledge to state how it works. @SpongeboB Sinewave would know but hasn't been on in a while. Could also call them. These are the same people that worked/created Outback and Trace so they know what they are doing.

 

[cs1234]

I do not have one since plans changed but had asked if they were able to be paralleled now (since originally they were not) and was told that that is now possible.

I'm sorry, for some reason I thought you were the guy from Midnite that comes here sometimes.. ?

 

[rhino]

On this page it does make a point about it:

wait, what’s that a ZERO transfer time! Yes, we said it ZERO transfer time.

 

[DIYrich]

On this page it does make a point about it:

In order to be Zero, it has to be double conversion (implied by the other operating modes), or else the Grid will sink the "parallel" connection. No other way since I have yet to hear about an AC Diode.

 

[rhino]

What exactly does double conversion mean in this case?

 

[PConlin]

By "double conversion" I mean power is converted from from grid AC to DC for battery charging. Then converting a second time from battery DC to load AC. Each conversion costs money due to less than perfect efficiency. A UPS has a relay that provides 100% efficient grid-to-load when the grid is working. At 12KW we might talking $1,200 to $1,500 per year in losses with servers running 24/7. That is not nothing. Both EG4 18KPV and the Sol-Ark 12K have such a straight path relay that avoids double conversion hence our attraction to the solution.

Sol-Ark markets their 15K as "5ms UPS no-glitch transfer". EG4 says their 18KPV is a UPS with "10ms transfer". Is the hardware all that much different? Can the Sol-Ark keep servers running during the grid-to-battery transfer while EG4 can't? Anyone know this for sure?

 

[DIYrich]

Try this test: Set the 18kpv to produce 100 watts to support load. Use the disconnect to disconnect from the grid see if it works.

Not a perfect test because disconnect is not sinking inverter output, but may indicate if it might work. Double converting 100 watts is minimal cost.

 

[Brucey]

This might just be a problem with the specific unit, as otherwise there'd be a bunch of posts about peoples pcs etc shutting down when switching from grid to battery? Unless people haven't tested by disconnecting the grid to check the behaviour and won't realize until the grid actually goes down?