Parallel connecting 4 100w panels

[Wandererrr]

I currently have two 100w solar panels connected in parallel and just got two more that I need to add in parallel. I just had surgery and am not thinking straight but only have one more day to use an Amazon gift card I have on the connecting pieces needed for connecting panels in parallel. How many do I need? Again, just can’t think straight. I can’t find a video that doesn’t talk about mixing series and parallel so if someone could easily explain how to connect them too that’d be super helpful.

 

[Tomthumb62]

You’ll need inline MC4 fuses, one for each panel. The size of fuse you need is listed on the back of the panel under “Max fuse rating”.

You need to use fuses if you connect more than two panels in parallel.

As for connecting, I use a 4 to 1 branch connector. Like this:

PowMr 1 to 4 Solar Branch connetors Panel Connectors Y Connector DIY Mount Tool in Pair MMMF+FFFM for Parallel Connection Between Solar Panels (1 Pair) https://a.co/d/aPTA8Rs

 

[Rocketman]

Another idea may be to do a 2s2p - connect 2 of those 100w panels in series - then connect the two strings in parallel.

You won’t need any other pieces (except mounting hardware).

(Don’t do this if you Solar charge controller is a PWM - it needs to be a mppt).

 

[Tomthumb62]

Another idea may be to do a 2s2p - connect 2 of those 100w panels in series - then connect the two strings in parallel.

You won’t need any other pieces (except mounting hardware).

(Don’t do this if you Solar charge controller is a PWM - it needs to be a mppt).

@Wandererrr , if you do 2s2p, you won’t need any inline mc4 fuses.

And if you do end up going 4p, besides the necessary fuses, you’ll want to make sure the wire coming from the combined panels (the “1” on the 4-to-1 branch connector) is at least 10awg for shorter runs or 8awg for long runs to the MPPT.

 

[Wandererrr]

You’ll need inline MC4 fuses, one for each panel. The size of fuse you need is listed on the back of the panel under “Max fuse rating”.

You need to use fuses if you connect more than two panels in parallel.

As for connecting, I use a 4 to 1 branch connector. Like this:

PowMr 1 to 4 Solar Branch connetors Panel Connectors Y Connector DIY Mount Tool in Pair MMMF+FFFM for Parallel Connection Between Solar Panels (1 Pair) https://a.co/d/aPTA8Rs

Do I need the 4 individual MC4 fuses if I get those 4 to 1 connectors? When I search MC4 fuse the results look like what the wires coming from the panels already look like. My panels are in my storage unit right now so I won't be able to look at the back of them until later.
Can I just buy that pair of 4 to 1 connectors and that'll be enough to make it a parallel group of panels?

 

[Wandererrr]

Another idea may be to do a 2s2p - connect 2 of those 100w panels in series - then connect the two strings in parallel.

You won’t need any other pieces (except mounting hardware).

(Don’t do this if you Solar charge controller is a PWM - it needs to be a mppt).

I'm doing 4 in parallel because I have 3 12v 100ah batteries and everybody has said that I need more watts of panels, and all of my devices are 12v. My batteries haven't fully charged since I got them supposedly because I don't have enough watts of panels. The main thing I want to run is my mini fridge 24/7, which I haven't been able to do.

 

[Wandererrr]

@Wandererrr , if you do 2s2p, you won’t need any inline mc4 fuses.

And if you do end up going 4p, besides the necessary fuses, you’ll want to make sure the wire coming from the combined panels (the “1” on the 4-to-1 branch connector) is at least 10awg for shorter runs or 8awg for long runs to the MPPT.

The previous owner of this skoolie set up the two solar panels and used 10awg wires to go straight down from the roof to the floor, probably about 6ft. Is that a short enough distance?

 

[45North]

(Don’t do this if you Solar charge controller is a PWM - it needs to be a mppt).

Not true!
Some PWM controllers can handle 24 volts, which is what you get with two 12v panels connected in series.
Yes, mppt controllers are preferable, in general but they cost a lot more.

 

[MisterSandals]

Some PWM controllers can handle 24 volts, which is what you get with two 12v panels connected in series.

A "12V panel" will output roughly 19Vmp so there's no way 2 in series is going to be acceptable for an SCC that accepts 24V max.

Is there a reason the OP won't reveal whether their SCC is PWM or MPPT? It would sure reduce the number of possible solutions bandied around here.

 

[45North]

A "12V panel" will output roughly 19Vmp so there's no way 2 in series is going to be acceptable for an SCC that accepts 24V max

Yes, many PWM controllers are rated for 12/24v nominal, same as the MPPT controllers.
Check Amazon if you still don't believe me.

 

[Rocketman]

Also, you want your two newest panels to as closely as possible match your two older panels. If putting them in parallel the Vmp should be as close as possible- hopefully within 5%.

 

[Tomthumb62]

Do I need the 4 individual MC4 fuses if I get those 4 to 1 connectors? When I search MC4 fuse the results look like what the wires coming from the panels already look like. My panels are in my storage unit right now so I won't be able to look at the back of them until later.
Can I just buy that pair of 4 to 1 connectors and that'll be enough to make it a parallel group of panels?

You need four mc4 fuses if you intend to put 3 or more panels in parallel. If you don’t, a fire could start in a worst case scenario. The fuses will prevent that.

Here’s an example of an mc4 fuse:

BougeRV 5PCS 15A Solar Fuses Holder Inline, 5PCS PV Inline Fuse Holders 15 Amp for Solar Panel and Solar Controller, Waterproof Solar Fuse Connector, Solar Surge Protection Device https://a.co/d/hJClso5

 

[Tomthumb62]

The previous owner of this skoolie set up the two solar panels and used 10awg wires to go straight down from the roof to the floor, probably about 6ft. Is that a short enough distance?

Yes that’s plenty short enough.

 

[Wandererrr]

A "12V panel" will output roughly 19Vmp so there's no way 2 in series is going to be acceptable for an SCC that accepts 24V max.

Is there a reason the OP won't reveal whether their SCC is PWM or MPPT? It would sure reduce the number of possible solutions bandied around here.

It’s MPPT. But I’m doing 4p not 2p2s

 

[Wandererrr]

Also, you want your two newest panels to as closely as possible match your two older panels. If putting them in parallel the Vmp should be as close as possible- hopefully within 5%.

What do you mean by match? They’re the same panels, 12v, 100w Renogy. And they’ll be placed as close as possible to the others. Do you mean the wires connecting them need to be the same length? How do I control the Vmp

 

[Wandererrr]

You need four mc4 fuses if you intend to put 3 or more panels in parallel. If you don’t, a fire could start in a worst case scenario. The fuses will prevent that.

Here’s an example of an mc4 fuse:

BougeRV 5PCS 15A Solar Fuses Holder Inline, 5PCS PV Inline Fuse Holders 15 Amp for Solar Panel and Solar Controller, Waterproof Solar Fuse Connector, Solar Surge Protection Device https://a.co/d/hJClso5

So I need to get both 4 of those and the 4 to 1 things? What amps do I need for both for 4 12v, 100w panels. 3 12v 100ah batteries. 1500w pure sine inverter. 30a MPPT charge controller. All batteries and panels in parallel.

 

[Rocketman]

Ok I was under the impression you would be buying different panels- so if they are all the same - then there is no issue with different electrical specs on the panels - the Vmp @ Imp.

Yes you will need four of the inline fuses and a set (one for positive line and one negative) of the 4-1 adapters.

I don’t understand your question- what amps do I need for panels, batteries, inverter, & mppt…

Are you meaning what size of wire is needed to handle the anmps annd to connect to each piece? If so…

The batteries - best practice is to get 3 sets of exactly the same length of cables and connect the batteries up to a bus bar. I would use #2awg.

I would have one set of bus bars for the battery- then on positive line a class T fuse, and on/off switch and on the negative line a shunt based battery monitor- like Victron Smartshunt or BMV712. (Use 2/0 for any wires in this area).
The other set of bus bars are for loads and chargers - each of these will need its own fuse to protect the wire.

From bus bar to 1500w inverter I would use 2/0

From bus bar to 30a mppt #10awg - you said you already had #10 from mppt to solar panels - (good size there).

Did that answer your question or did I misinterpret it?

Good luck

 

[Tomthumb62]

So I need to get both 4 of those and the 4 to 1 things?

Yes you need four fuses and one 4-1 branch connector. The rating of the fuse you need is listed on the BACK of your solar panels under "max fuse rating".

What amps do I need for both for 4 12v, 100w panels. 3 12v 100ah batteries.
1500w pure sine inverter. 30a MPPT charge controller. All batteries and panels in parallel.

Not sure I understand the question. Sorry, can you rephrase?

 

[Wandererrr]

Ok I was under the impression you would be buying different panels- so if they are all the same - then there is no issue with different electrical specs on the panels - the Vmp @ Imp.

Yes you will need four of the inline fuses and a set (one for positive line and one negative) of the 4-1 adapters.

I don’t understand your question- what amps do I need for panels, batteries, inverter, & mppt…

Are you meaning what size of wire is needed to handle the anmps annd to connect to each piece? If so…

The batteries - best practice is to get 3 sets of exactly the same length of cables and connect the batteries up to a bus bar. I would use #2awg.

I would have one set of bus bars for the battery- then on positive line a class T fuse, and on/off switch and on the negative line a shunt based battery monitor- like Victron Smartshunt or BMV712. (Use 2/0 for any wires in this area).
The other set of bus bars are for loads and chargers - each of these will need its own fuse to protect the wire.

From bus bar to 1500w inverter I would use 2/0

From bus bar to 30a mppt #10awg - you said you already had #10 from mppt to solar panels - (good size there).

Did that answer your question or did I misinterpret it?

Good luck

I don’t have bus bars, is that okay? Can I just get the fuses and 4 to 1 connectors?
I was asking what amp rating the fuses need to be. I saw the answer is on the back of the panels.

 

[Wandererrr]

Yes you need four fuses and one 4-1 branch connector. The rating of the fuse you need is listed on the BACK of your solar panels under "max fuse rating".

Not sure I understand the question. Sorry, can you rephrase?

You answered my question. The back of the panels say the fuse rating should be 15a. So I’ll get four 15a fuses and one set of two 4to1 branch connectors, then I’ll be all good?

Edit:
Does it matter if I get different brands, or if they’re solid pieces vs lengthy cords, like these two different options
PAEKQ 4 to 1 Solar Panel Connectors T Branch Connectors Cable Splitter Coupler 1 Male to 4 Female (M/4F) and 1 Female to 4 Male (F/4M) for Parallel Connection Between Solar Panels (1 Pair) https://a.co/d/iECppRD
Vs
BougeRV Solar Y Branch Connectors Extra Long Solar Panel Parallel Connectors 1 to 4 Solar Cable Wire Plug Tool Kit (M/FFFF and F/MMMM) https://a.co/d/3Nnkh5v

And are there a lot of varying factors between different brands of fuses? Or will it be safe to get the cheapest option?