Mixing solar panels.

[TBDOML]

Newbie question here, I recently purchased a 2022 GT23' ftb it came with the stock solar with one 90 watt panel. I decided to add 2 more 90 watt zamp panels to the system, so I ordered them from amazon. Amazon messed up and sent one 90 watt and one 170 watt panels. Will these work well together in the stock setup? Thanks.

[uncle_bob]

Hi

What matters is the solar in vs power out curve. As long as the shape matches up, the power does not matter. Usually the easy way to match things is to get same / same panels.

Bob

[lewster]

Actually, you will only get the 90 watt output from your 170 watt panel in your system. As you already have 3 X 90 watt panels, your 170 watt panel will output the same amount as your 90's. I would send it back and get the 90 you ordered! Less space and better looks!

[Ephraim]

Originally Posted by lewster

Actually, you will only get the 90 watt output from your 170 watt panel in your system. As you already have 3 X 90 watt panels, your 170 watt panel will output the same amount as your 90's. I would send it back and get the 90 you ordered! Less space and better looks!

Not actually true. What matters is the voltage curve. If the voltage curve is close to the same, you will get close to the rated power. (Assuming they are in parallel). If the voltage curve is not the same, then you may have issues. Test the open circuit voltage of both the 90 W panels and the 170W panel to see how close they are. If they aren’t drastically different you will be fine. Since the panels are not balanced it won’t operate at peak efficiency but it will still work and you’ll get good output power from all the panels. The more the open circuit voltage varies between the panels, the worse it will perform. You can also adjust how the panels are wired together.

An easy way to see if it will work is to count the number of cells in each panel. Equal number of individual cells is good no matter what their size. If the counts are different you may have issues.

[1StreamDream]

I think this is a bit more complex. I have zamp panels on my roof, I installed myself and I have a mix of 90w and 100w panels. Zamp has a couple different product lines, my panels are the newest (at the time I did this) and they are known as the “obsidian” series. Low profile and slightly higher voltage than the earlier generation product line. The first suggestion I will offer is that you want all your panels to be of the same product line (which should mean they all operate at the same voltage level). I don’t know what the AS factory does, but I believe the most common wiring of multiple solar panels is parallel, and in that approach it is important that all panels operate at the same voltage. If you wire them in series, the panel voltages don’t matter but there are other trade offs you will make if you go that route. It might appear to work if you mix them (in parallel) but you will lose efficiency somewhere if the voltages fight each other. Hope that helps you.

[Ephraim]

Originally Posted by 1StreamDream

I think this is a bit more complex. I have zamp panels on my roof, I installed myself and I have a mix of 90w and 100w panels. Zamp has a couple different product lines, my panels are the newest (at the time I did this) and they are known as the “obsidian” series. Low profile and slightly higher voltage than the earlier generation product line. The first suggestion I will offer is that you want all your panels to be of the same product line (which should mean they all operate at the same voltage level). I don’t know what the AS factory does, but I believe the most common wiring of multiple solar panels is parallel, and in that approach it is important that all panels operate at the same voltage. If you wire them in series, the panel voltages don’t matter but there are other trade offs you will make if you go that route. It might appear to work if you mix them (in parallel) but you will lose efficiency somewhere if the voltages fight each other. Hope that helps you.

If the panels are wired in parallel, the voltage is the important factor. Efficiency of panels makes a small difference in voltage, but the deciding factor is how many cells are in series within the panel. That’s why you can count cells and know if they will work together or not. As long as the series cell count is the same there will be very little loss when hooking dissimilar panels together in parallel.

If you are connecting them in series, the current carrying capability is what counts. You are limited by the smallest current panel. A larger panel will not carry more current than the smallest panel.

Most panels designed for rv use will have an open circuit voltage of 24 to 36 volts. Panels designed for grid tie will have a higher cell count and will often have voltages above 45; volts. You can’t parallel such dissimilar panels. Grid tie panels will often also have a series-parallel scheme of cells to increase both the voltage and current.

It used to be that you had to use rv panels on a 12v system but with modern mppt controllers you can use the panels with higher cell counts.

[TBDOML]

Thanks for all the replies, I decided to install the 170W panel. I have 2 90W panels, one on each side of the front of the roof, and I installed the 170W panel behind the AC unit.

I believe they are running in parallel, they are all plugged into the stock zamp 3 way input. I am seeing Pmax of 340W on my Victron Connect App history. I believe this is the highest solar input each day.

BTW the voltage was the same for the 90 and 170.

[JamuJoe]

Originally Posted by TBDOML

Newbie question here, I recently purchased a 2022 GT23' ftb it came with the stock solar with one 90 watt panel. I decided to add 2 more 90 watt zamp panels to the system, so I ordered them from amazon. Amazon messed up and sent one 90 watt and one 170 watt panels. Will these work well together in the stock setup? Thanks.

Mixing solar panels gets complicated. Here is a good tutorial. https://solarpanelsvenue.com/mixing-solar-panels/