400 watt solar on a ProMaster Van

[CompMan2020]

Hi all,

Need a little help with my setup. I currently have 200 watts of solar on my van (2 x100 watt Sungold Power panels) with a EPEVER 30amp MPPT, 3000 Watt Pure sine inverter and 4 100ah AGM batteries. I ordered 2 more 100 watt panels. I'm not sure what configuration would be best for my setup, All 4 panels in series or 2 in series and then the 2 strings in parallel? Watched a few of Will's videos but I'm still a bit confused on the benefits of parallel vs. series.

Linked Equipment being used - My first 2 panels - Sungold power, The new ones - Newpowa, MPPT, Inverter

Any help will be greatly appreciated!

Rich.

 

[eXodus]

When you look in the specs of the EPEVER it states something like 72V maximum - each of those panels produces roughly 20-22V x4 in series - that's to much.

So you you are correct - 2 panels in series and those two strings then parallel.

 

[learning all the time]

I have been watching a lot of videos on this. Will has done some as you said. Alt-E store does a lot of these videos. These videos seem to disprove Mono over Poly and several other theories but this is not usually a true event. The best answer I have come up with is test your system all 3 ways and see which works out the best with your equipment. I am in the process of upgrading my batteries and adding 300 watts more and will be testing these all three versions. One thing that to note: if you go parallel check your connectors max amp rating. I have some that handle 60 amps. My personal preference is for parallel as shade won't completely shut me down but to each their own.

 

[CompMan2020]

When you look in the specs of the EPEVER it states something like 72V maximum - each of those panels produces roughly 20-22V x4 in series - that's to much.

So you you are correct - 2 panels in series and those two strings then parallel.

That’s where most of my confusion comes into play, It actually says 92V max so all in series should be fine, but I still don’t see where the different wiring configurations benefit one over the other. In Will’s wiring diagram he used a 40amp MPPT for the 400 watt solar array.

 

[CompMan2020]

I have been watching a lot of videos on this. Will has done some as you said. Alt-E store does a lot of these videos. These videos seem to disprove Mono over Poly and several other theories but this is not usually a true event. The best answer I have come up with is test your system all 3 ways and see which works out the best with your equipment. I am in the process of upgrading my batteries and adding 300 watts more and will be testing these all three versions. One thing that to note: if you go parallel check your connectors max amp rating. I have some that handle 60 amps. My personal preference is for parallel as shade won't completely shut me down but to each their own.

Yes I can do this but since I’m a novice I didn’t want to risk damaging any of the equipment without knowing for sure which configuration is best.

 

[learning all the time]

As Exodus states, check your Epever spec sheets and all your equipment ratings. As long as your panels are powered within limits it should not damage your equipment. Especially if fused properly. You might also want to verify you have proper wiring size. Renogy has a great calculator on their web site.

 

[HaldorEE]

My understanding is that one shaded panel essentially kills the entire output of a series connected set of panels. If this is true, then using a 2S2P configuration would mean you would only lose half of your solar input when a panel gets shaded.

Please correct me if my understanding is incorrect.

 

[HaldorEE]

And I wouldn't push the recommended max voltage. You have to use the panels Open Circuit voltage rating and allow for cold temperature (cold panels put out higher volts).

Exceeding the max limit by even a fraction of a volt can result in the magic smoke leaking out.

My design criteria is to never plan to use more than 80% of a devices max voltage rating. 72V is about 80% of 92V and that is a reasonable limit to use. That is assuming that not having your SCC fail catastrophically is important to you.

Unlike the panel wiring, this is something I am extremely certain about.

 

[eXodus]

That’s where most of my confusion comes into play, It actually says 92V max so all in series should be fine, but I still don’t see where the different wiring configurations benefit one over the other. In Will’s wiring diagram he used a 40amp MPPT for the 400 watt solar array.

One shaded panel will kill the output of whole string.

So when you got 4 parallel - you got more wire loss but when one panel is shaded - you loose only one.
When you go 2p2s then one shaded panel will let you loose two panels

When you got all 4 in series - one shaded panel will take them all offline.

I think 2 parallel with two strings is the best of both worlds - high enough voltage and still redundancy.

Thats what Will posted anyhow:

 

[JoeHam]

My understanding is that one shaded panel essentially kills the entire output of a series connected set of panels.

Please correct me if my understanding is incorrect.

When I cover one of my series panels I still get output FWIW.

 

[learning all the time]

When I cover one of my series panels I still get output FWIW.

And this goes back to my earlier comment. Everytime my research says one thing, someone else proves differently. My personal belief is the quality of solar panels is so getting so much better.

 

[CompMan2020]

And this goes back to my earlier comment. Everytime my research says one thing, someone else proves differently. My personal belief is the quality of solar panels is so getting so much better.

So I’m back to my initial question... Series or parallel? Guess I will have to try the different scenarios and see for myself.

 

[eXodus]

So I’m back to my initial question... Series or parallel? Guess I will have to try the different scenarios and see for myself.

you can go half way.

The general issue with this question is - every panel is different, every charge controller is different, every van is different and people are sitting on different points of the globe.

Some panels work better in low light, some better in heat.

I've got one charge controller for each panel I got one micro-inverter per panel on my house and thought, why not on the Van?

 

[CompMan2020]

you can go half way.

The general issue with this question is - every panel is different, every charge controller is different, every van is different and people are sitting on different points of the globe.

Some panels work better in low light, some better in heat.

I've got one charge controller for each panel I got one micro-inverter per panel on my house and thought, why not on the Van?

Yeah, guess ill go with the 2 series strings, then parallel to the charge controller. Thanks for the Help / Guidance to all!

 

[Zil]

With agm battery, having the panels in parallel would give you good service. If you ever change to LiFePo4 then you will gain the most from MPPT so 2p2s would be better.

 

[NPhil]

When I cover one of my series panels I still get output FWIW.

I have read (in the description of panels) that the bypass diodes (usually included) are supposed to prevent a shaded panel from shutting off the whole string.

 

[fratermus]

Hi all,

I'm not sure what configuration would be best for my setup, All 4 panels in series or 2 in series and then the 2 strings in parallel? Watched a few of Will's videos but I'm still a bit confused on the benefits of parallel vs. series.

It's part guesswork, part experimentation, and part Holy War. I encourage you to try all the technically-acceptable arrangements to see what happens in your typical use conditions. Since there is typically only one set of wires going through the roof, rearranging the panels configuration is just climbing the ladder and and changing MC4 connection arrangements.

On my Promaster I used to have 3x 24v panels which I ran in parallel (Vmp ~36v, the pic in my avatar) on a EpEver BN-series controller. After a recent upgrade I now run 3x nominal 20v panels in series (Vmp ~90v) on it.

Anecdote: I was camping under pine canopies in Ruidsoso last week and was making 27% of rated power at around 10am with one shaded panel. I can't promise you similar results but I can say with say from experience that series + shade is not necessarily a zero-watt scenario. Having said that, I do take measures to avoid shade, including using the Sun Surveyor app to assess potential camping spots. It overlays the sun's path on the camera view so you can see where/if shade will be an issue.

additional thoughts on the various arrangements

 

[fratermus]

bypass diodes (usually included) are supposed to prevent a shaded panel from shutting off the whole string.

My understanding is bypass diodes in the panel's junction box are for routing around shaded substrings within the panel itself, {and} are not intended to intervene between separate panels in series.

 

[fratermus]

With agm battery, having the panels in parallel would give you good service. If you ever change to LiFePo4 then you will gain the most from MPPT so 2p2s would be better.

Can you please flesh out the thinking on these statements? Right now I am having trouble following the line of reasoning.

 

[NPhil]

My understanding is bypass diodes in the panel's junction box are for routing around shaded substrings within the panel itself, {and} are not intended to intervene between separate panels in series.

I'm testing two panels in series right now, and have a minivan filled with cardboard. I think I will go out and test it in a few minutes.