Loss of power between solar and inverter

[dude8604]

I have a grid tied GS4048A with 3.6kW of solar panels. I'm seeing a decent amount of power loss between the solar charge controller and the inverter and I can't figure out why. For example, in the image, 0.36kW is unaccounted for. I guess some could be going to the batteries, but this happens even when the battery is at 100% I have the charging settings according to the battery manufacturer's instructions. I'm posting images of what I think are the relevant settings, but please tell me if there's anything else you need to see. Thanks for your help!

[dude8604]

More settings

Another image showing power loss at 100% battery

[raysun]

Another image showing power loss at 100% battery

What kind of battery?
How old?

[Mike Curran]

I don't have a screenshot to share but I often see the same thing with my Rolls battery system. It's a huge, 15 year old battery and even after charge parameters are met, 100% SOC and selling to grid, there's still 3-400 watts going into the battery to keep it at the sell setpoint (pretty close to float, actually). I'll post an Optics power flow screenshot next time I see it, gotta catch it on a sunny mid-day.

[fcwlp]

Since you have a FNDC a more accurate measure is to put your cursor over the battery which shows what the shunts are measuring in and out if you have at least two shunts.

[dude8604]

Since you have a FNDC a more accurate measure is to put your cursor over the battery which shows what the shunts are measuring in and out if you have at least two shunts.

I do have two shunts, but where do I find what voltage to multiply to get the wattage?

[dude8604]

I don't have a screenshot to share but I often see the same thing with my Rolls battery system. It's a huge, 15 year old battery and even after charge parameters are met, 100% SOC and selling to grid, there's still 3-400 watts going into the battery to keep it at the sell setpoint (pretty close to float, actually). I'll post an Optics power flow screenshot next time I see it, gotta catch it on a sunny mid-day.

My batteries were replaced about two years ago.

[EA6LE-ONE]

I don't have a screenshot to share but I often see the same thing with my Rolls battery system. It's a huge, 15 year old battery and even after charge parameters are met, 100% SOC and selling to grid, there's still 3-400 watts going into the battery to keep it at the sell setpoint (pretty close to float, actually). I'll post an Optics power flow screenshot next time I see it, gotta catch it on a sunny mid-day.

My batteries were replaced about two years ago.

What type of battery is? model?
need to check the maximum charging current for the battery and have global charge enabled if necessary.
acid batteries will continue to draw power once they are considered charged.

edit: from the charging parameter looks like is a flooded Lead acid battery. might need to set the global charge to 48A. check the battery setting from manufacturer.

[dude8604]

I don't have a screenshot to share but I often see the same thing with my Rolls battery system. It's a huge, 15 year old battery and even after charge parameters are met, 100% SOC and selling to grid, there's still 3-400 watts going into the battery to keep it at the sell setpoint (pretty close to float, actually). I'll post an Optics power flow screenshot next time I see it, gotta catch it on a sunny mid-day.

My batteries were replaced about two years ago.

What type of battery is? model?
need to check the maximum charging current for the battery and have global charge enabled if necessary.
acid batteries will continue to draw power once they are considered charged.

edit: from the charging parameter looks like is a flooded Lead acid battery. might need to set the global charge to 48A. check the battery setting from manufacturer.

These are the batteries: https://invertersrus.com/product/lifeline-gpl8dl/
I have 4 of them wired in series.
The technical manual says the maximum charge current is 5C, which would be 1275A, but that seems really high.
Here is the technical manual: https://lifelinebatteries.com/wp-conten ... -06-19.pdf
Also, in the event log it looks like it's only doing bulk charging, it never says Absorb or Float charging. Is that a problem?

[raysun]

These are the batteries: https://invertersrus.com/product/lifeline-gpl8dl/
I have 4 of them wired in series.

A little battery math:
48V @ 225AH = 10.8kWH total energy capacity
50% usable (50 Depth of Discharge) = 112.5AH or 5.4kWH.
The battery has sufficient capacity for a "grid backup" role. It would support about a 500W average load for 10 hours before needing recharging.

The technical manual says the maximum charge current is 5C, which would be 1275A, but that seems really high.

The modern AGM battery cells have very low internal impedance, and can tolerate high charge currents. I would think charging at 5C would be excessive, however. The charger in the GS4048A at maximum will put out roughly 55A charge current. The FM80 has a maximum output of 80A but will peak at less than that with the specified array.
Both chargers, combine for less than 135A charging current and would appear safe for the battery during Bulk.

Also, in the event log it looks like it's only doing bulk charging, it never says Absorb or Float charging. Is that a problem?

It would appear the battery is not being fully charged. The battery should be fully charged at least once a week. Keeping a Lead Acid battery at or near full charge is best for maximum service life.

Try manually initiating a Bulk charge using the Radian. From OpticsRE:

[fcwlp]

I do have two shunts, but where do I find what voltage to multiply to get the wattage?

Use the voltage that shows right below the battery symbol in OpticsRE.

[Mike Curran]

This screenshot shows 140 watts going to the battery to maintain voltage at the sell setpoint, 27.2 volts (now showing 27.1 volts), with SOC = 100%. Not unusual.

First sunny day in awhile.

Edit: View suggested by fcwlp. Note +600 watts to battery