Hybrid Grid-Tied system: what if I remove the batteries?

[DickyDck]

Was wondering in trying to figure out some strange behavior my system sporadically produces.... what if I just removed the batteries from the equation? is there a way to just make it as though they didn't exist from the system settings? or would I have to physically disconnect the terminals on the string?

[ButchDeal]

Was wondering in trying to figure out some strange behavior my system sporadically produces.... what if I just removed the batteries from the equation? is there a way to just make it as though they didn't exist from the system settings? or would I have to physically disconnect the terminals on the string?

and what brand and model of system do you have??

[Tecnodave]

Dickydck

With the Schnieder XW+ 6848 the batteries are what run the inverter, you cannot use this system without the batteries, Just not designed that way. They stabilize the voltage coming from the charge controller, totally nessecary

[DickyDck]

yep, that's what I thought. I have to do the math to figure out how many Lithium batteries I would have to get to match 440ah. As you guys were helping me a while back with the fact my installer underspeced/under provisioned the amount of batteries I needed. It's been over a year now, and I don't want to add fresh batteries to the existing pool. I'm thinking going lithium, it will cost a crap ton more but they in theory will last longer.

[DickyDck]

also, thanks you guys, I really appreciate the expert opinions and advice. it helps a lot!

[DickyDck]

what would happen... in theory.... if I told the inverter I had 440ah worth of batteries? would my bank explode and burn my house down while killing my dog and cat in the process?

[Mike90250]

440ah of batteries only affects the calculations for charging rates and time till empty. I've told my XW I have 1000ah, so when I call for 20% charge rate, it's a 20A rate

But there is another issue. Ripple Current. For every KW of power the inverter delivers, you need about 100ah of battery, which acts as a giant capacitor when producing AC power. So if you are exporting 2.5kw , you need at least 250 ah of batteries, otherwise the inverter will not have a "stout enough" supply feed and it's internal capacitors overheat (error W45) (really bad for the health of the inverter)

You have good solid gear, that costs a lot of money. Trying to "game it" with mucking around with cheap stuff or trying to fool it, is not going to make you happy. If you need new batteries, get new batteries.

[inetdog]

Depending on the type and your load cycles, Lithium may not last longer than Lead Acid, especially Flooded.They will be less affected by extended Partial State Of Charge (PSOC) time during operation.


Also, depending on the design of the hybrid inverter, with no batteries it might shut down and not restart properly whenever the power from the panel array is interrupted. Like by clouds or night.

[DickyDck]

Mike90250 thanks!!! I think you just solved my problem for me! My system by raw calculations is a 7.2kw system. I've only ever seen 6 at max for short periods of time but that is realistic numbers with actual sunlight etc. my batt bank is 220ah, and every now and again the system just stops producing power, and then spoils back up and it generally only happens on bright ass days.

"For every KW of power the inverter delivers, you need about 100ah of battery, which acts as a giant capacitor when producing AC power. So if you are exporting 2.5kw , you need at least 250 ah of batteries, otherwise the inverter will not have a "stout enough" supply feed and it's internal capacitors overheat (error W45) (really bad for the health of the inverter)"


so tomorrow since since it is supposed to be sunny here I'm going to switch off a few strings at the combiner and see if I still get the intermittent power stop. You rawk! I'll let you guys know how this turns out

[Mike90250]

You can use the SCP or combox to read the error codes and not have to guess as to whats going on.

[DickyDck]

I'm not getting any error codes, which is odd. You would guess that things are chugging along at 5kw+ fine one sec, then you hear the inverter shutdown, the readings go to -:-- then it spins back up to 5kw or whatever it was, it would trigger an error right?

[Mike90250]

I expect it would need at least 30 minutes to cool back down. And never having had mine in that condition, I don't know if it lights an error light.

[DickyDck]

This is just informational in my logs, but what is EPOCH and why does it seem to log this at the top of every hour...

Old Epoch:2019-6-12 11:59:59 New Epoch:2019-6-12 12:0:0 new10mins

really the only thing in the logs so far