2 400 watt panels 2 200 watt panels

[datsolardude]

Okay I am wondering if I could mix these three solar panels together? Would I lose efficiency? I'm coming up with a game plan on how to wire them.

I have one of these
Renogy 200 Watt 12 Volt... https://www.amazon.com/dp/B07RFQVB9M?ref=ppx_pop_mob_ap_share

I have one of these
Newpowa 200W Monocrystalline 200 Watt 12V Solar Panel High Efficiency Mono Module RV Marine Boat Off Grid https://www.amazon.com/dp/B07VBL7XKV/ref=cm_sw_r_apanp_5WvmBX9vfm4AZ

I have two of these

BougeRV 400W 12V 10BB Mono Solar Panel

Looking for a high-performance solar panel? The monocrystalline panels, 10BB cell design, and all-black design make the 400W 10BB solar panel an exceptional choice for you.

www.bougerv.com

 

[zanydroid]

How are you going to wire them?

When in series current needs to match (IE K’s current law)

When in parallel voltage needs to match (IE K’s voltage law)

If I was doing this my starting point would be to assume voltages are the same so I would need two parallel 200W to match one 400W. But I didn’t look at your data sheet. If they were pasted at screenshots I could have (takes too long to dig into Amazon links to hunt for them)

 

[datsolardude]

Parallel

 

[zanydroid]

All parallel, probably ok. Paste the voltage specs or self check them

You will need a fused combiner with correct fuse size per branch. Simple way is to match max fuse rating on the specs.

 

[datsolardude]

How are you going to wire them?

When in series current needs to match (IE K’s current law)

When in parallel voltage needs to match (IE K’s voltage law)

If I was doing this my starting point would be to assume voltages are the same so I would need two parallel 200W to match one 400W. But I didn’t look at your data sheet. If they were pasted at screenshots I could have (takes too long to dig into Amazon links to hunt for them)

Hope this works found 2 so far

 

[zanydroid]

LOL. The “12V” 400W panel is just a regular voltage/current 400W panel. Which means it’s much higher than the 200W.

Based on those numbers you can already conclude that you absolutely need 2s of the small panels in parallel with the 400Ws to match the voltage. The current is about more mismatched than the voltage

 

[datsolardude]

So how do I do this? Because i'm about to buy this bus bar
Joinfworld Heavy Duty 500A Bus Bar Waterproof Power Distribution Block with 2*5/16"(M8)+2*3/8"(M10) Studs 48V DC Automotive Marine Battery Terminal distribution Block with Cover - Negative&Positive https://a.co/d/9f4zCY3

How should I wire these panels for this to work?

 

[datsolardude]

Am I supposed to wire the two hundred watt panels together in the series as its own string? And then run the other 400 watt panels in parallel?

 

[zanydroid]

Oops the voltages don’t match. I was comparing Voc to Vmp.

Actual math or spreadsheet / app needs to be used to figure out the difference between the options. I suspect there will be a 30% loss on part of the system. Maybe take the L on the 200W panels and just run with the 400W. Save the 200W for something else / use it as a learning experience for pre planning

That busbar is unfamiliar to me. I cannot visualize how it helps. Seems like it’s for battery side

Can you find a thread covering beginner combiner boxes for your application? I’m not comfortable sending you a link bc it may not be beginner friendly

 

[zanydroid]

FWIW I would recommend shopping online solar supply house like Signature Solar over Amazon. A lot of crap on Amazon.

 

[datsolardude]

I've been looking on Amazon for parallel branch connectors, but none of them will work for the 800 watts, So I want to go with this bus bar To act as the parallel branch connector for my solar panels. Looks like I need something for 2 panels. Would this work?

 

[zanydroid]

There's no fuses and you have to make special adapters for those to make MC4 work with screw terminals... that smells very wrong wrt a sane approach b/c of all the extra work for no value.

This type of box can easily handle it, except as stock this only has 10A fuses. Those 13.79A ISC 400W panels will need some smart shopping / modding of parts to make work. The issue here is that 400W panels used to be <10A and a lot of equipment is sized for the old style.

https://www.amazon.com/Combiner-Briidea-Breakers-Lightning-Waterproof/dp/B09WY6VTGT/ref=sr_1_10?crid=MTPNKBZPHT0Z&keywords=dihool+solar+combiner+box&qid=1704011852&sprefix=dihool+solar+combiner+box%2Caps%2C121&sr=8-10

For instance both of these SS solar are below what you need:

All Products - System Components - Combiner Boxes - Signature Solar

signaturesolar.com

But the Bouge RV manual confirms my calculation that 25A fuse is what you need for the 400W panel



If you stay under 2P you can use the following, no fuses. All you have to do is find a pre-made 8 AWG MC4 OR buy the special 8AWG MC4, some PV cable, crimp tool, and make it yourself. I'm not sure if the standard crimp tool takes up to 8 AWG.

Staubli MC4 Branch Plug and Socket

Signature Solar provides solar panels, off-grid solar systems, grid-tie, and hybrid systems. Quality solar inverters, bifacial solar panels, complete solar kits, solar batteries. Featuring brands such as EG4 Electronics with their solar battery, LifePower4 and EG4 LLifePower4 and EG4 LL

signaturesolar.com

 

[datsolardude]

Looks like that combiner box is not going to be able to handle 30 to 40 amps from the 400 watt panels. Been looking at those too and it's be been challenging to find

 

[zanydroid]

If you're willing to pay a premium you can find someone selling Midnite Combiner box and ask them to quote the right custom config. You can see in the datasheet that it easily handles your use case if filled with the right fuses or breakers

https://www.altestore.com/static/datafiles/Others/MNPV_CombinerBox_Datasheet_V2.pdf

If you buy those modular boxes from Amazon you can swap parts out. With the ones that have fuse holders, you can check whether they can hold bigger fuses and swap the fuses themselves.

That Staubli branch is rated to 50A so you just have to find the Staubli #8 MC4 connectors and a crimp tool. You might hit a problem with minimum order size though (probably around $20-25). Maybe if you find one place that has both #8 and the MC4 connectors you can get closer. And you can e-mail/ask them to confirm that the MC4s you get are the right ones. Another way is to order regular #10 MC4 and #10 PV to get the order size up, you can have a much cleaner install if you cut your own PV to size, and I trust PV cables I make myself, using MC4 connectors from same supply houses that solar installers use, over buying premade PV cables from Amazon.

 

[zanydroid]

I took a quick look at the Bridea listing, there are some fairly knowledgeable people in the comments talking about the build quality etc, and changing the fuses. It needs connections checked.

The fuse holders from customer provided pictures show 20A (so I assume that's the biggest fuse you can put in, replacing the 10A it comes with), so if you have good solar conditions it can potentially be exceeded which would require you to swap fuses.

If you end up needing a bigger fuse holder, there might not be enough space left and the surge protector would need to be removed.

NEC wants fuses and wires sized to 13.79A (ISC) * 1.56 = 21.5A

 

[zanydroid]

If I was just doing a basic setup I would probably do the Staubli combiners with #8 custom cable. And 2P the 400W panels together. The shade resistance would be nice. If the panels need to go a long distance then I would probably look at what the 2S vs 2P voltage drop loss, as well as the cost of 8/2 vs 10/2 wiring.

Depending on how expensive the SCC, Inverter, and battery are, and how exposed the panels are / what the local weather is like, I might add surge protector at some point. Surge protectors are fairly cheap, it's more a question of laziness / finding a good place to put them. If there is already a place with a DIN rail, then it's hard to argue against just wiring one in.

Still don't like the 30% mismatch between 200W and 400W panels on both current and voltage.

 

[datsolardude]

Yeah, I'm going to just stick with the 400. Watt panels, my question is how I'm going to parallel wire the two panels together with a proper branch connector that can handle the maximum capability 800 watts can put out. From reviews and videos I've seen of these panels. They can produce over 400 W per panel.

 

[zanydroid]

This is a supply house of a lot of solar stuff. The installer/consultant/distributor guy that did the parts ordering for me for my grid tie install used them to get me my MC4 connectors, Jinko connectors, and PV wire. And when I ordered some special Jinko tools from a random website, turns out the random website just forwarded the order to Titan.

OneMonroe Titan | #1 Source for All Solar Needs

OneMonroe Titan is the solar industrial leader in solar panel connectors, crimping tools, wire and cable, safety labels, and much more!

titanwnc.com

I checked for you, they have both #8 PV (which you need to go into the connector) and 8 AWG MC4. You can try shooting their sales staff an e-mail. I suspect they might also carry the branch connector.

 

[zanydroid]

Another thing to consider is, if you want to go beyond 2P at some point (and not to 2P2S), then it is smart to plan ahead for that. Esp if you have to run the #8 output a long distance.

The #8 MC4 would have to get ripped out, and you need to go to combiner box.

75A and 100A wire size does get a little crazy though.

 

[ShaneC]

These are going on the roof of an RV I assume? Both at the same angle, I really don't understand why you don't just save a lot of hassle and connect in series. Also again, if you can return these panels and buy normal 400w ones do it. You've been ripped off, sorry.