Learned a new thing today.

[bborzell]

Was discussing GoPower upgrade options with tech support today. After I gave him the list of all the components currently in the electrical system, he asked me the following question:

“Did you know that the 100 amp suitcase panel you are running into the GoPower controller has the effect of throttling down the production from the two 190 panels on the roof?”

He mentioned that the MPPT controller I was asking about would reduce the degree of reduction, but that the system would ratchet back toward the production capability of the lowest wattage panel. In effect, if all three panels were seeing the sun in a similar way, the 480 watt potential would be maxed out at <300 watts. Interesting.

I mentioned that my intent, in using the 100 watt suitcase was to chase the sun when the roof panels are blocked. He agreed that this was the best use of the non controller panel unless I wanted to mount another controller and run the suitcase to the batteries.

[Mike G]

Very interesting. Thanks for posting this. Seems there would be a benefit to routing the portable panel through a separate controller, like he says. Maybe run the power into the 7-pin pigtail instead of the zamp port; I think it would be easier than opening up a battery box and clipping leads onto the posts.

[tdf-texas]

Originally Posted by bborzell

Was discussing GoPower upgrade options with tech support today. After I gave him the list of all the components currently in the electrical system, he asked me the following question:

“Did you know that the 100 amp suitcase panel you are running into the GoPower controller has the effect of throttling down the production from the two 190 panels on the roof?”

He mentioned that the MPPT controller I was asking about would reduce the degree of reduction, but that the system would ratchet back toward the production capability of the lowest wattage panel. In effect, if all three panels were seeing the sun in a similar way, the 480 watt potential would be maxed out at <300 watts. Interesting.

I mentioned that my intent, in using the 100 watt suitcase was to chase the sun when the roof panels are blocked. He agreed that this was the best use of the non controller panel unless I wanted to mount another controller and run the suitcase to the batteries.

It sounds like "tech support" left a few details out that make the situation confusing.

Connecting three solar panels that operate at the same voltage in parallel will have an output that sums the current output of the three panels. So, two panels that put out 10 amps and one panel that puts out 5 amps has a total of 25 amps being supplied. The panel voltages are the same but no current is lost from using different size panels.

The only way that the panels would operate like "tech support" said is if they were connected in series. When installing solar panels in series, the voltage adds up, but the current is limited to the lowest solar panel output. For example, if you installed 3 15v solar panels in series – with one solar panel rated 5 amps and the other two rated at 10 amps – you’d only have 5 amps being supplied at 45 volts.

As you have a PWM solar controller, your panels should be connected in parallel.

If you like to learn more about solar systems, a good website source is below.

https://www.explorist.life/solar-pan...s-vs-parallel/

[Rockhead]

Thank you TDF

[Perry Butler]

Originally Posted by tdf-texas

It sounds like "tech support" left a few details out that make the situation confusing.

Connecting three solar panels that operate at the same voltage in parallel will have an output that sums the current output of the three panels. So, two panels that put out 10 amps and one panel that puts out 5 amps has a total of 25 amps being supplied. The panel voltages are the same but no current is lost from using different size panels.

The only way that the panels would operate like "tech support" said is if they were connected in series. When installing solar panels in series, the voltage adds up, but the current is limited to the lowest solar panel output. For example, if you installed 3 15v solar panels in series – with one solar panel rated 5 amps and the other two rated at 10 amps – you’d only have 5 amps being supplied at 45 volts.

As you have a PWM solar controller, your panels should be connected in parallel.

If you like to learn more about solar systems, a good website source is below.

https://www.explorist.life/solar-pan...s-vs-parallel/

When I added three 100 watt panels to our 170 watt that came with our Escape the choice was wire them in series giving us a total of 400.3 watts or wiring them in parallel for a total of 463.7 watts. Needless to say they are wired in parallel.

For solar, find someone knowledgeable about solar. Like tdf-texas, I also advise using Explorist.life for proper solar installs. Explorist.life used to have a neat calculator for figuring series vs parallel on the page tdf-texas linked but now it's gone, so you have to use paper pencil, but the results were still the same.

Enjoy,

Perry