Hello, I am trying to add 2 100w panels to my single 200w panel in parallel. VOC on my 200w panel is 24.4v, on the 100w panel 21.4v. Same manufacturer, same tech (mono). I know that your are supposed to keep the same VOC but what happens if I can't because of dimensional restrictions, am I just losing a little power at the controller or can I do damage to my system. Thx for the help.
Open Circuit voltage issues?
- Thread starter wntrhwk
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efficientPV
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That shouldn't be a problem. What you want to match is the Vmp voltage and yours is probably only about a volt difference.
Of course I am assuming what you told me is wrong. 200W panel is a 24v panel and the two 100W panels are in series.
Of course I am assuming what you told me is wrong. 200W panel is a 24v panel and the two 100W panels are in series.
Most 200W panels have a higher voltage than 24... but if you are correct, all in parallel should work...
I wouldn't do it. But it should work.
Paralleling the 2 -100w panels to keep the voltage the same will allow you to treat them as if they were one 200w panel to connect how you like with the 200w panel. With a MPPT controler you should see little if any loss.
I am presently doing that myself at the moment but with 2-200w in series with 2 in parallel 100w. (like 3S), than in parallel with another set the same.
I am presently doing that myself at the moment but with 2-200w in series with 2 in parallel 100w. (like 3S), than in parallel with another set the same.
Hello EfficientPV, sorry for the late response, thought I would get notifications. Anyway, I am including the full specs below. I only have the one 180w panel currently, my plan is to buy the 2 100w panels and parallel everything together. Thx for your patience and help.
Bouge 180w
VMP-19.54
VOC-23.84
IMP-9.21
ISC-9.57
Bouge 100w
VMP-18.5
VOC-21.4
IMP-5.51
ISC-6.11
RCinFLA
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The lower voltage of the 100 watt panel will reduce the power output of the 180 watt panel if run in parallel.
Check to see if the specs are stated at the same temperature. Sometimes they rate at 25 degs C (STC), sometimes at 40 degs C. (NOC). NOC spec's will have lower panel Voc and Vmp voltages than 25 degs C.
Check to see if the specs are stated at the same temperature. Sometimes they rate at 25 degs C (STC), sometimes at 40 degs C. (NOC). NOC spec's will have lower panel Voc and Vmp voltages than 25 degs C.
One other question. I understand I won't have full output because of the 100w panels, is there some math that will tell me the output of all 3 in parallel? I am also guessing that if I went this route I am not damaging my system, just have the lower output penalty. Thx again for the help.
RCinFLA
Solar Wizard
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There is math but it is complicated and transcendental, meaning it can only be solved by multiple iterations.
Basically it depends on diode voltage vs current curves which are logarithmic.
In your case example, the 100 watt panel will be dragged slightly higher above its optimum Vmp and 180 watt panel will be dragged slightly lower than its optimum Vmp.
Just solve the bottom three simultaneous equations for common paralleled panel Vout voltage.
Basically it depends on diode voltage vs current curves which are logarithmic.
In your case example, the 100 watt panel will be dragged slightly higher above its optimum Vmp and 180 watt panel will be dragged slightly lower than its optimum Vmp.
Just solve the bottom three simultaneous equations for common paralleled panel Vout voltage.
So, beyond the intense math, can I assume that I will not damage my controller?There is math but it is complicated and transcendental, meaning it can only be solved by multiple iterations.
Basically it depends on diode voltage vs current curves which are logarithmic.
In your case example, the 100 watt panel will be dragged slightly higher above its optimum Vmp and 180 watt panel will be dragged slightly lower than its optimum Vmp.
Just solve the bottom three simultaneous equations for common paralleled panel Vout voltage.
View attachment 160074
Thx much, appreciate the help. Hope you have a good evening.
