Full Sun but not full power?

[pda1]

Well, here's another curiosity. I now have a 1.5 kW array (2s3p) and the system runs quite well in full Sun up to about 400w output from the panels and charging the batteries and then feeding the Inverter. The MPPT shows "Float" so all is well. However, with no load, when I put a heavy load on the system, such as a 1kW hair dryer most of the power is provided by the batteries (2- 12v LIF...BB) that being around 900w.

I had thought that the panels would provide it all?

Any ideas on what's wrong of wrong with my assumptions?

Thanks,

Peter

 

[Rednecktek]

Nope, that's about right. A solar panel is just an over-glorified battery charger so your batteries are doing the work feeding the inverter, the panels are just replacing what comes out of the batteries.

If everything is working right, the MPPT should kick up the wattage coming from the panels to replace what your load test is draining from them, so it should kick out of "Float" mode once the batteries are really working and go back when they're fully charged again.

Sounds like everything is working correctly.

 

[timselectric]

This is typical for systems built with individual pieces of equipment. (SCC, inverter) my AIO, will power the load directly from the solar. And the batteries only kick in when needed.

 

[chrisski]

IME when in float, the power needed comes from the battery for a few seconds until the MPPT controller provides as much power as the panel will allow, which should be 100% From the panels if the energy is there.

I had Trojan FLA batteries and charged them per specs, and it worked fine.

I switched to lithium batteries, and I had to tweak my Bulk and float settings to get this to work, but I it did. These settings were slightly different on the two different systems I have with lithium batteries. The lithium batteries were built from cells which only had a charge no higher than rate, not bulk or float.

IF these are lithium batteries, AND there is no spec sheet for them, you MAY consider increasing the float voltage. At first on my lithium batteries in float, the MPPT only used 30% of power back into that I was using. A 300 watt load as pushing 100 watts back in with 900 watts of panels. I stepped up the float voltage in .1 VDC increments until I was at 300 watts from the panels.

By doing this, there is some risk that the lithium batteries won’t last as long because they’re floated too high. If I did not do this, I risked going into the night at a 30% SOC because charging was done early in the day. Regardless, I WOULD NOT go against what a spec sheet says.

IME, in full sun my portable panels pointed at and angled to a noon time sun will provide 100% of rated power in March; however, my rooftop flat panels will provide about 60% of rated power.

 

[pda1]

This is typical for systems built with individual pieces of equipment. (SCC, inverter) my AIO, will power the load directly from the solar. And the batteries only kick in when needed.

What is an AIO?

 

[timselectric]

What is an AIO?

All in one
A single unit that has the inverter, solar charge controller, grid charge controller, and transfer switch, all built in.

 

[pda1]

My batteries are Battle Born 12v 100ah- 2 in series to provide 24v.

I might phrased my question ambiguously.

I meant, when using a 1kW hair dryer the batteries provide about 900w through the inverter instead of the panels providing the majority of power. My array is 1.5kW. The longer the hair dryer runs the lower the battery voltage...it drops fast. Yes, the mppt switches to Bulk once the battery voltage drops below 27v but the panels do not increase their output power to quickly make up for battery usage.

 

[timselectric]

I would think that it should, since it is in bulk mode.

 

[timselectric]

Others here, can probably help you figure it out.
But, you'll need to provide the specs for your system.
The more information, the better.
And, it will minimize the questions.

 

[pda1]

Here's my equipment.....but now I have 6 panels instead of 4.

Equipment

 

[MisterSandals]

(2s3p) and the system runs quite well in full Sun up to about 400w output from the panels

What is the most you ever get from your array? If 400W, I would check the connections. Each 2S string should output 2x the panel Vmp and 1x the Imp.
The combined array should output 3x the Imp.

 

[MisterSandals]

You equipment says 4 panels. Yet here you say your array is 1.5kW 2S3P.

 

[MisterSandals]

The cheap audio breakers might be part of your problem. Is there voltage loss after the breakers. Are they getting hot (especially the one for the inverter)?

 

[pda1]

You equipment says 4 panels. Yet here you say your array is 1.5kW 2S3P.

Please read my comment just above.....it mentions the 6 panels.

 

[pda1]

The cheap audio breakers might be part of your problem. Is there voltage loss after the breakers. Are they getting hot (especially the one for the inverter)?

No mention of audio breakers in my list of components. Perhaps you are referring to the battery switches. Those are rated for 200a.

Nothing gets hot. The inverter only gets slightly warm at most.

 

[timselectric]

The cheap audio breakers might be part of your problem. Is there voltage loss after the breakers. Are they getting hot (especially the one for the inverter)?

Zooming in, they look like fuses possibly.

 

[MisterSandals]

No mention of audio breakers in my list of components.

Nothing gets hot. The inverter only gets slightly warm at most.

Oh crap, sorry. Viewing on iPad… should have looked closer.

I still think your array have connection problems if it’s only producing 400W max.

 

[robby]

What is the most you ever get from your array? If 400W, I would check the connections. Each 2S string should output 2x the panel Vmp and 1x the Imp.
The combined array should output 3x the Imp.

I thought i was reading something wrong when no one else mentioned only 400W from a 1.5Kw array as being a major problem. He has either got bad wiring or a dead panel or two. I would suggest that he goes through the wiring carefully and check all connections. If that yields nothing then tear down the wiring and check each panel one at a time for output voltage Voc and short circuit current.

 

[pda1]

Zooming in, they look like fuses possibly.

Oh....yes....there are 3 fuses....don't immediately remember the amperage....maybe 60 or more.

 

[timselectric]

Also, if your panels are facing in different directions. You could have one string (possibly shaded) pulling the other string/strings (in full sun) down.