Can a 340W panel AND a 100W panel be used at the same time?

StuartV

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My 2nd post, whoop!

So I bought an Iconica 1KVA All in one hybrid solar charger inverter the other week, and bought a Trina 340W panel and an Ultramax 100aH Lifepo4 battery.

All hooked up, battery 1st etc.

I want to add another solar panel to produce more electricity to use, and to charge battery when no electricity is being drawn. I want to get either a 100W panel, or a 150W panel.....but will it work with what I already have?

Specs are:

INVERTER MODEL
1KVA
Max. PV Array Open Circuit Voltage = 102 Vdc
PV Array MPPT Voltage Range = 15~80Vdc
Charging current = 60A

Trina 340W panel:
Peak Power Watts-PMAX (Wp) 340
Maximum Power Voltage-UMPP (V) 34.2
Maximum Power Current-IMPP (A) 9.94
Open Circuit Voltage-UOC (V) 41.1
Short Circuit Current-ISC (A) 10.6
Module Efficiency ηm (%) 19.9

100W Renogy panel:
Maximum Power at STC: 100W
Cell Efficiency: 22%
Optimum Operating Voltage (Vmp): 20.4V
Open-Circuit Voltage (Voc): 24.3V
Optimum Operating Current (Imp): 4.91A
Short-Circuit Current (Isc): 5.21A

I have read through 10 pages of posts, read a fair few, and have watched some videos from Amy at AltE power or whatever they're called, but I'm still confused.

Series, parallel, amps, voltages....rice crispies!

The Iconica specs on websites say max solar is 500W, but then the specs for the MPPT model which I have, suggest I can have more than 500W of solar panels.

So, can I used the 340W panel I have, and add another 100/150W panel and get more power?

(I did get 314W out the Trina today, best I've seen so far!)

I'm in the UK btw 👍

Thanks for your replies in advance
 

sunshine_eggo

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Can you? Yes, but you absolutely shouldn't.

Panels in parallel should have very similar Vmp-Voc values.
Panels in series should have nearly identical Imp-Isc values. If they aren't, the panels will operate at the LOWEST rated current in the string.

Violating the two rules above may dramatically reduce output and be WORSE than if you left the mismatched panel out.

340W, Vmp 34.2, Imp 9.94
100W, Vmp 20.4, Imp 4.91

If you put them in parallel, you will force the 340W panel to operate at the much lower 20-24V range of the 100W panel. That would cut the 340W panel down to about 230W MAX. Total array output: 330W Max - less than the 340W alone.

If you put them in series, you will force the 340W panel to output no more than 4.91A. This would cut the 340W down to 168W. Total array output: 268W - less than the 340W alone.
 

StuartV

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Location
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Can you? Yes, but you absolutely shouldn't.
Panels in parallel should have very similar Vmp-Voc values.
Panels in series should have nearly identical Imp-Isc values. If they aren't, the panels will operate at the LOWEST rated current in the string.

Violating the two rules above may dramatically reduce output and be WORSE than if you left the mismatched panel out.

340W, Vmp 34.2, Imp 9.94
100W, Vmp 20.4, Imp 4.91

If you put them in parallel, you will force the 340W panel to operate at the much lower 20-24V range of the 100W panel. That would cut the 340W panel down to about 230W MAX. Total array output: 330W Max - less than the 340W alone.

If you put them in series, you will force the 340W panel to output no more than 4.91A. This would cut the 340W down to 168W. Total array output: 268W - less than the 340W alone.

Thanks for your reply 👍

There is a 2nd panel I've been looking at, a 175w panel with these specs:

Max Power at STC: 175W
Open Circuit Voltage: 21.6V
Short Circuit Current: 10.35A
Opitmum Operating Voltage: 17.95V
Optimum Operating Current: 9.75A

The Amp seems to be more inline with the Trina panel, would you think this panel would work better with it? Only issue with this panel, it would take me above the 500W max panel for the all in one, would take it to 515W 😬

Orrrr, should I just buy some new matching panels and sell on the 340Wpanel?

Much appreciated 😉
 

sunshine_eggo

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Can you? Yes, but you absolutely shouldn't.


Thanks for your reply 👍

There is a 2nd panel I've been looking at, a 175w panel with these specs:

Max Power at STC: 175W
Open Circuit Voltage: 21.6V
Short Circuit Current: 10.35A
Opitmum Operating Voltage: 17.95V
Optimum Operating Current: 9.75A

The Amp seems to be more inline with the Trina panel, would you think this panel would work better with it? Only issue with this panel, it would take me above the 500W max panel for the all in one, would take it to 515W 😬

Orrrr, should I just buy some new matching panels and sell on the 340Wpanel?

Much appreciated 😉

Series should be fine. Very small penalty to the 340W panel.

Most MPPT list the maximum power they can output, which does not mean that you can't put more on it. In the vast majority of cases, as long as you don't exceed the PV input limits for Voc and current (assume it's the same as the output if not specified), you're good.

I would not hesitate to run that combo of panels in series as long as you're safely under the Voc limit of the MPPT.

Honestly, I'd get a second 340W and string them in parallel or series as the Voc limit demands and run 680W.
 
Last edited:

73powerstroke

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Jun 17, 2022
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Arizona
Can you? Yes, but you absolutely shouldn't.

Panels in parallel should have very similar Vmp-Voc values.
Panels in series should have nearly identical Imp-Isc values. If they aren't, the panels will operate at the LOWEST rated current in the string.

Violating the two rules above may dramatically reduce output and be WORSE than if you left the mismatched panel out.

340W, Vmp 34.2, Imp 9.94
100W, Vmp 20.4, Imp 4.91

If you put them in parallel, you will force the 340W panel to operate at the much lower 20-24V range of the 100W panel. That would cut the 340W panel down to about 230W MAX. Total array output: 330W Max - less than the 340W alone.

If you put them in series, you will force the 340W panel to output no more than 4.91A. This would cut the 340W down to 168W. Total array output: 268W - less than the 340W alone.
Maybe he could put each on their own charge controller lol
 

pollenface

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I used a 80+100w panel config with an mppt for a couple of years with one of my sheds. Was it theoretically ideal? No. Did it work? Yes.
 

sunshine_eggo

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Thanks for the answers, I ended up buying another 340W panels as 2 of them were slightly below the max specs on my mppt charger 👍😉

Thanks for following up.

In the vast majority of cases, MPPT are tolerant to over-paneling provided you do not exceed Voc limits. Given your MPPT output of 60A:

60A * 14.4V = 864W

I wouldn't hesitate to put a 2S2P array of your panels (1360W) on your MPPT. MPPT are basically "loads" to panels. Even if the panels can provide more current than the MPPT can use, the MPPT will only pull what it can use.
 

rin67630

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I used a 80+100w panel config with an mppt for a couple of years with one of my sheds. Was it theoretically ideal? No. Did it work? Yes.
80+100w panels are usually 18Vmp. You can parallel them. On a 12V battery, the best deal is a PWM controller.
 

rin67630

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Thanks for the answers, I ended up buying another 340W panels as 2 of them were slightly below the max specs on my mppt charger 👍😉
...be careful, don't tease the max Vin of the MPPT controllers.
Under very cold but bright sunny weather the Voc can significantly exceed he specs.
 

Sirtate

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May 27, 2021
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Thanks for following up.

In the vast majority of cases, MPPT are tolerant to over-paneling provided you do not exceed Voc limits. Given your MPPT output of 60A:

60A * 14.4V = 864W

I wouldn't hesitate to put a 2S2P array of your panels (1360W) on your MPPT. MPPT are basically "loads" to panels. Even if the panels can provide more current than the MPPT can use, the MPPT will only pull what it can use.
I agree...

As long as you don't push too many volts into the SCC, it'll be fine...

It's kinda like plugging a phone charger into a 120v socket at home, and then replacing that charger with a hair dryer. One uses more power, but as long as you don't exceed the rated voltage, they just pull as much power as they want/need at the moment.

Over panelling allows more useful charging in the "shoulder" periods where hard, direct sun isn't available... (cloudy days, too)
 
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