18kpv input vs output question

Hello everyone,

I’m hoping someone can help me understand my solar system data.

I have 16,200W of solar panels ( 4 arrays of 9 450W panels each- 36 total panels).

These plug into an EG4 18kpv.

I have 6 EG4 life power batteries (48v)

I’m grid tied and I do net-metering with my local utility company.

Today was a very nice/sunny day and I was very surprised to see my PV input capped out at around 13000, and my daily graph had a very capped/flattop appearance most of the afternoon. I pasted a pic of my data curve below.

I understand that I can only push up to 12KW to the grid (net-meter) at any given time.

Let’s say If my solar is able to make 16kw and let’s say my house (loads) is needing 2kw, and I can only net meter 12kw, is the other 2kw “lost/wasted?”

Will the 18kpv allow me to net-meter 12kw and run 4k of loads simultaneously? Or does the inverter only allow 12kw at anytime going to a combination of battery, house or grid)?

Why have an inverter that can take in 18kw of PV but only have 12kw of output?

I hope my question makes sense.

Follow-on question would be what is the best way to maximize your production with battery and net-metering?

Thanks in advance!

Everything above the 12k, can be used to charge the battery. As long as the battery isn't full.

You can do 12kw ac. So that’s both load to house and selling back to the grid. The rest can be used to charge the battery which is dc.
So I have mine setup to charge the battery from 11:30am which is about when I hit the 12kw limit on the pv side so it then uses that excess power to charge the battery. That way I clip at a higher pv kw although I still leave some to get wasted. You however shouldn’t clip with that amount of battery. You can just set battery “charge last” enabled and/or set the time in “pv charge priority”

Just be cognizant of with only using charge last enabled, it will only charge the battery last after loads and export so would only kick in after 12kw of ac generated. That is on a big sunny day. On a cloudy day it might never charge the batteries. Which is why I also have pv charge priority set to force battery charge from pv at midday no matter what.

EZPZ said:

Just be cognizant of with only using charge last enabled, it will only charge the battery last after loads and export so would only kick in after 12kw of ac generated. That is on a big sunny day. On a cloudy day it might never charge the batteries. Which is why I also have pv charge priority set to force battery charge from pv at midday no matter what.

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He has net metering. Save batteries to soak up excess pv.

Love this group! Thank you all so much!

EZPZ said:

You can do 12kw ac. So that’s both load to house and selling back to the grid. The rest can be used to charge the battery which is dc.
So I have mine setup to charge the battery from 11:30am which is about when I hit the 12kw limit on the pv side so it then uses that excess power to charge the battery. That way I clip at a higher pv kw although I still leave some to get wasted. You however shouldn’t clip with that amount of battery. You can just set battery “charge last” enabled and/or set the time in “pv charge priority”

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Thank you so much for your reply. I don’t see a “charge last” setting in my app. Is it only on the inverter itself? And just to confirm, you do both “charge last” and set PV priority charge times? Do you not charge with AC?

I pasted my settings below. Grateful for your input.

I don’t use the app but go via the web interface. I personally don’t use ac charge at all as even on very cloudy days I generate enough pv to fully charge my battery everyday.

And yes I use both charge last and pv priority. And my reasons are as follows - I want to have my battery fully charge by nightfall so it can discharge and power the house overnight and I want to use as much pv as possible during the day. These are my settings as they work for me to make my battery work and not just sit there twiddling its thumbs. Note that with pv priority, the battery will charge first with pv and will not discharge during those times.

I start clipping at around 11am on a sunny day, so charge last catches that excess power and sends it to charge the battery before pv priority kicks in. If it’s not a sunny day, the pv priority ensures that during the “peak” sunlight hours the battery gets charged, irrespective of the charge last setting.

Thank you!

EZPZ said:

And yes I use both charge last and pv priority. And my reasons are as follows - I want to have my battery fully charge by nightfall so it can discharge and power the house overnight and I want to use as much pv as possible during the day. These are my settings as they work for me to make my battery work and not just sit there twiddling its thumbs. Note that with pv priority, the battery will charge first with pv and will not discharge during those times.

View attachment 213061

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I found the settings in the web version!

13kW output from 16kW (STC rating) of panels seems pretty good to me. I'd say that is about maximum output.

Does anybody regularly see output that approaches the STC rating for your panels? I usually allow 20-25% of the STC rating for system loss.

I hit 15-16k range regularly and then start clipping depending really on the amount of wattage I can send to the battery at that time. That’s from 16.8k panels but they are however bifacial. Sure I could pull more if I had more batteries that needing charging so I wouldn’t clip.