Solar generation proportional to AC load demand?

I have two MPP Hybrid units each fed by it's own 1300 Watt array. Each inverter is powering separate AC circuits via a reliance transfer switch. What I'm seeing is that when the load doesn't demand it the PV doesn't produce as much. For example if the load is say 250 Watts the PV may produce 500 Watts. If I increase the load to say 900 Watts the PV output jumps up to 800 Watts. Turn off that load and the PV output drops. The unit is also configured to use solar to charge the battery bank so its allocation some watts it's producing to the batteries. In the example above about 4 amps would be going to the battery - When I increase the load the amps to battery goes to 0 but as soon as I drop the load the amps to battery goes to 25 or so for about 8 seconds and then back to 4 amps.

Why isn't the PV always generating everything it's capable of without an AC load? If the load requirement is not there, the need to charge the battery bank is and I'd think it would be pushing everything it can to get the batteries charged.

Forgive me if this a noob question - It just seems to me that I'm leaving capacity on the table and strikes me as odd that the panels produce more only when I ask them to

Mac6792 said:

I have two MPP Hybrid units

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I don't know the answer but you should really identify your "MPP Hybrid units" with specific models.
And when you mention "load" is that load connected to your MPP Hybrid(s) or load on the battery bank?
<edit> hmm, maybe you did specify this:
<youwrote/>Each inverter is powering separate AC circuits via a reliance transfer switch.
</edit>

I could see this making a difference if you had a low amp (~25amp) MPP Hybrid where the total throughput is limited.

MisterSandals said:

I don't know the answer but you should really identify your "MPP Hybrid units" with specific models.
And when you mention "load" is that load connected to your MPP Hybrid(s) or load on the battery bank?
<edit> hmm, maybe you did specify this:
<youwrote/>Each inverter is powering separate AC circuits via a reliance transfer switch.
</edit>

I could see this making a difference if you had a low amp (~25amp) MPP Hybrid where the total throughput is limited.

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These are lv2424s they can push a ton of amperage via the mppt solar charging. There is no limit on throughput the issue is pv generation rises based on load requirements. I'd think that the PV would generate whatever it's capable of and if the loads don't require it then they push it all to the battery until charged. Then it drops on the floor. That's not happening

How and where are you measuring?

Via the display screens on both inverters

if the batteries are full then no current will flow from the charge controller to the batteries.
If you then create a load current will flow from the charge controller to the load.

Batteries are not close to being full. What I'm reading is the PV output screen. When there is a higher load demand the PV output increases.

If there is enough sun to produce this additional power why isn't the system always producing it regardless of demand. In the example in my original post, the batteries need charging. If the system can ramp up from 500-800 watts of PV input based on load demand , then why doesn't it do that when the batteries are half full. Is there some sort of algorithm preventing this.?

Adding to this-. There are also times when I have full power coming from the panels (full sun) and I have about 80% demand on the inverter . In this case there is also more power going to the batteries.

Simply put I think It's all controlled by an algorithm. There are times when there's enough sun to increase the PV generation substantially to meet an AC load requirement but it chooses not to increase the PV generation to charge the batteries faster

Mac6792 said:

Batteries are not close to being full. What I'm reading is the PV output screen. When there is a higher load demand the PV output increases.

If there is enough sun to produce this additional power why isn't the system always producing it regardless of demand. In the example in my original post, the batteries need charging. If the system can ramp up from 500-800 watts of PV input based on load demand , then why doesn't it do that when the batteries are half full. Is there some sort of algorithm preventing this.?

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Batteries accept less current as they fill up.

smoothJoey said:

Batteries accept less current as they fill up.

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Interesting....that may be the cause..

Mac6792 said:

Why isn't the PV always generating everything it's capable of without an AC load? If the load requirement is not there, the need to charge the battery bank is and I'd think it would be pushing everything it can to get the batteries charged.

Forgive me if this a noob question - It just seems to me that I'm leaving capacity on the table and strikes me as odd that the panels produce more only when I ask them to

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PV panels are a peculiar type of electrical sources. Unless the electrons are promptly transported away from the panels (to run a load, or charge a battery bank), they recombine. This is the reason for finite Voc of the cells. You can't build up the voltage without limit. It is the task of the charging system to manage the energy from the panels. If you have too little storage (or load) relative to generation capacity, you're are indeed leaving untapped energy on the table.

Ok - Follow up to this. The whole system needed to be reset. Everything now seems to be working as expected - panels are now pushing full capacity to cover loads as well as 70amps to charge the batteries. In other words loads on both inverters total 500 watts but the panels are producing 2200 watts with the excess going to the battery - That's what I was expecting but wasn't seeing.

Mac6792 said:

The whole system needed to be reset.

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How exactly does one reset the whole system? This process is new to me.

MisterSandals said:

How exactly does one reset the whole system? This process is new to me.

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Powered everything down and back up. There was something wonky in the software going on

Mac6792 said:

Powered everything down and back up.

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I was wondering why the sun flickered for a few seconds earlier.