4 405w panels vs 12 100w panels...

Hedges

I See Electromagnetic Fields!
Joined
Mar 28, 2020
Messages
8,363
If rated input current is 120A (2500W input at 21.4V) then I'd use at least 150A fuse (25% larger than continuous current)

The goal is for fuse to never blow. Not unless there is an actual short.
 

HRTKD

Boondocker
Joined
Apr 24, 2020
Messages
5,977
Location
Somewhere South of Denver
ok, so i would get the 15a inline fuse holder, take out 15a fuse and replace with 12a fuse. Am I understanding this correctly?

Fuse holders with no fuse should be available. I think I bought one from Windy Nation. But it was a good 8 months ago and my memory isn't what it used to be.
 

fafrd

Photon Sorcerer
Joined
Aug 11, 2020
Messages
2,206
Hello. I am in a little dilemma with setting up my solar. I initially bought 10 100w panels which i found out is a newbie mistake.
Woops. I set up a return for them with amazon because it was free returns and placed an order with a1solar for 4 405w panels instead.
I know you’re stuck with the 100W panels and now focused on a solution based on those, but da*m, that’s a pretty good price on those 405W panels (especially for only 4).

Extra panels means extra costs for wiring and more importantly, extra cost for more racking.

I get my racking system for about $25/panel, so that’s another $250 for only $1000W ($0.25/W) versus $100 to rack the 4 larger panels delivering $1620W ($0.062/W).

So if you still had a choice to make (of for next time), fewer, more-powerful panels are almost always preferable to more smaller-powered panels ($/W being roughly equivalent).


I’ve not heard of A1 Superstore before - how did you hear about them. Does anyone here on the Forum have any experience with them?
 

Tbleppy

New Member
Joined
Feb 4, 2021
Messages
83
If rated input current is 120A (2500W input at 21.4V) then I'd use at least 150A fuse (25% larger than continuous current)

The goal is for fuse to never blow. Not unless there is an actual short.
Is this a good 12a fuse?


does it matter fast acting or slow? Ceramic or not? Some say 250V, some say 600V. Which one do I need?

heres the fuse holder i was thinking of getting too
 

Tbleppy

New Member
Joined
Feb 4, 2021
Messages
83
I know you’re stuck with the 100W panels and now focused on a solution based on those, but da*m, that’s a pretty good price on those 405W panels (especially for only 4).

Extra panels means extra costs for wiring and more importantly, extra cost for more racking.

I get my racking system for about $25/panel, so that’s another $250 for only $1000W ($0.25/W) versus $100 to rack the 4 larger panels delivering $1620W ($0.062/W).

So if you still had a choice to make (of for next time), fewer, more-powerful panels are almost always preferable to more smaller-powered panels ($/W being roughly equivalent).


I’ve not heard of A1 Superstore before - how did you hear about them. Does anyone here on the Forum have any experience with them?
not superstore, solarstore. Its A1solarstore.com. Based in FL. They came up when i searched for buy solar panels or a similar search term to that. Ive never heard of them or any of the companies so it made no difference who i clicked on. After i checked several out, i went with them. They had good deals and a good freight price of only $175 for up to 12 panels. Thats why i was really bummed they rejected my order. Really weird because it was 2 days later and i got an email saying cs failed. The email also said hey will not process my order due to suspected fraud. Thats a pretty hefty claim and they back it up with nothing. Just saying i dont know when i called them. I finally did get through to my bank and they said they didnt reject anything and a1 must not accept that form of payment--visa?!? That made me remember that a1 had said to pay with paypal. I dont have that and I dont really want it. But on top of all of that, the $ had been removed from my account but then placed back. It was odd. Then i realize theres a lot of shady business on the web and im nervous about it now.
 

Tbleppy

New Member
Joined
Feb 4, 2021
Messages
83
Will this work for the 50amp fuse:
not sure of fuse type for the fuse before charge controller.

im doing inline fuses from the panels, using 6 y connectors and will place the inline fuses just before the first y connection on all 4 of the positive wires. No fuses on the negative wires. This will be done on the exterior of house. Once it is down to 2 cables(1 positive, one negative) it will enter the house through a small hole in the wall. That will have the cc attached to the wall. So I could easily attach the 50a circuit breaker to the wall just to the side of cc and run the wires through that first. Those wires will be 10awg. Upon exiting the cc it will use 8awg wires to go directly to the battery bank. Im undecided whether batteries will be lined up in a row or squared together as 2 rows of 2. But the 8awg red will connect to the nearest positive terminal whereas the 8awg black will stretch to the farthest negative terminal. Then the 2/0 awg wires will connect batteries 2s2p. 2/0awg to inverter next. Not sure which battery posts the battery to.inverter connection should use. 7inches from the positive battery post will have a class t 150a fuse. Not sure if that should be attached to the wall or dangle inline. I suppose the instructions would say but i dont have it yet. Class t fuse and holder and i know the fuse bolts to the holder. Will it be compatible with the thickness of the wire, 2/0?

i know i left out the busbar because im thouroughly confused about it still. The battery company said its my personal preference to use one or not but if i do it should be 500amp. I want the busbar if it is the right thing to do. I want to know what all is connected to a bus bar? For example? I dont understand. Its still DC at that point so is it for the DC appliances? Are there other applications for it?

also unclear about hardwiring the inverter.
 

Hedges

I See Electromagnetic Fields!
Joined
Mar 28, 2020
Messages
8,363

Voltage has to be at least as high as your series string Voc and DC rated.
I don't know if any glass have the rating.


Those 1/4" fuses aren't the size for that fuse holder.

here's one:

 

HRTKD

Boondocker
Joined
Apr 24, 2020
Messages
5,977
Location
Somewhere South of Denver

Save yourself some headache. Get the fuse and fuse holder from the same place. Here is where I bought mine:

 

Tbleppy

New Member
Joined
Feb 4, 2021
Messages
83
Save yourself some headache. Get the fuse and fuse holder from the same place. Here is where I bought mine:

im finding 10a or 15a fuse and holder:

my panel specs say max series fuse 12a. How do i proceed? Bump it up to 15a? I am having trouble finding th inline fuse for 12a.

it sounds like this fuse:

will fit in this holder:

ill take out the 15a fuse and replace with 12a fuse.

thanks for the help with that. I would like to know what type of fuse is ideal for the 50a before charge controller. It is a 40amp cc. Renogy says do 40a fuse. But 50a is what im advised here. Should i look for anl fuse type? Cn anyone show me a good one?
 

HRTKD

Boondocker
Joined
Apr 24, 2020
Messages
5,977
Location
Somewhere South of Denver
thanks for the help with that. I would like to know what type of fuse is ideal for the 50a before charge controller. It is a 40amp cc. Renogy says do 40a fuse. But 50a is what im advised here. Should i look for anl fuse type? Cn anyone show me a good one?

CC? Need to be specific here. Solar charge controller? If so, the Blue Sea 185 type circuit breaker is fine.

Solar panel -> circuit breaker -> solar charge controller -> circuit breaker -> common bus bar

The two circuit breakers in the above "diagram" will be different. The first one will be for the amount of amps the solar panels, as a set, will produced. The second one is for maximum amount of amps the solar charge controller is rated for.

Both circuit breakers will follow the amp rating x 1.25 formula.
 

Hedges

I See Electromagnetic Fields!
Joined
Mar 28, 2020
Messages
8,363
Im thnking about getting this:

That works too.
Might be more convenient than in-line fuse holders. Bulkier. Can integrate a disconnect (breaker)
That listing is just the box, already as expensive as four fuses, fuse holders, some "Y" cables.
Add to that either four DIN rail fuse holders and fuses, or four breakers.

If you go with fuse holders, optionally add one breaker for the combined wire as a disconnect.

Fuses and fuse holders (by the box, can find individual from other vendors)

http://www.midnitesolar.com/products.php?menuItem=products&productCat_ID=22

Here are breakers:


If breakers, I have an objection to them (that the company behind them doesn't agree with.)
Those are "polarized", meaning can safely interrupt current only flowing in one direction not the other.

The story about what happens if used backwards (and that they work fine in one direction)



If oriented to interrupt current from PV panel to charge controller, then if a PV panel was shorted and current from other three panels flowed back into it (the reason fuse or breaker is required by code), then it can't interrupt the current, may burn up.
My suggestion is to put a stiff wire through the holes in the breaker handles, so they are mechanically ganged together. When one trips due to excessive current flowing backward through it, the other three turn off and stop the current.

The following shows breakers up to 3-pole ganged. I have one with 6-poles which they used to sell. The handles are ganged with a metal pin:

 

Tbleppy

New Member
Joined
Feb 4, 2021
Messages
83
CC? Need to be specific here. Solar charge controller? If so, the Blue Sea 185 type circuit breaker is fine.

Solar panel -> circuit breaker -> solar charge controller -> circuit breaker -> common bus bar

The two circuit breakers in the above "diagram" will be different. The first one will be for the amount of amps the solar panels, as a set, will produced. The second one is for maximum amount of amps the solar charge controller is rated for.

Both circuit breakers will follow the amp rating x 1.25 formula.
CC? Need to be specific here. Solar charge controller? If so, the Blue Sea 185 type circuit breaker is fine.

Solar panel -> circuit breaker -> solar charge controller -> circuit breaker -> common bus bar

The two circuit breakers in the above "diagram" will be different. The first one will be for the amount of amps the solar panels, as a set, will produced. The second one is for maximum amount of amps the solar charge controller is rated for.

Both circuit breakers will follow the amp rating x 1.25 formula.
would this fuse work

i tried your link and its a discontinued item

solar panel - twelve amp inline fuses per parallel string - solar charge controller - fifty amp fuse or circuit breaker - busbar
is the busbar for dc powered loads
 

HRTKD

Boondocker
Joined
Apr 24, 2020
Messages
5,977
Location
Somewhere South of Denver
Your 12 amp fuses protect between parallel strings. I think you still want a circuit breaker just before the solar charge controller. Besides providing over current protection, it also gives you a way to turn off all PV power going to the solar charge controller.

Are these the correct specs for your 100 watt panels?
Maximum Power Voltage (Vmp): 18.78V
Maximum Power Current (Imp): 5.32A
Maximum System Voltage: 1000V DC
Open-Circuit Voltage (Voc): 22.64V
Short-Circuit Current (Isc): 5.7A

What is your configuration of the panels? 5s2p, 2s5p?

A 50 amp circuit breaker downstream of the solar charge controller will work if the solar charge controller is rated for less than 50 amps output, more like 40 amps.
 

Tbleppy

New Member
Joined
Feb 4, 2021
Messages
83
Are these the correct specs for your 100 watt panels?
Maximum Power Voltage (Vmp): 18.78V
Maximum Power Current (Imp): 5.32A
Maximum System Voltage: 1000V DC
Open-Circuit Voltage (Voc): 22.64V
Short-Circuit Current (Isc): 5.7A

those are the correct specs.






What is your configuration of the panels? 5s2p, 2s5p?


its not configured yet. They will be soon though. I had been thinking 3s4p. Do you think it would be better to do 5s2p or 2s5p? I have 4 12v batteries which I am setting up 2s2p. My charge controller is 12/24v and it is 40a. My inverter is 24v and is 2000w.
 

Tbleppy

New Member
Joined
Feb 4, 2021
Messages
83
That works too.
Might be more convenient than in-line fuse holders. Bulkier. Can integrate a disconnect (breaker)
That listing is just the box, already as expensive as four fuses, fuse holders, some "Y" cables.
Add to that either four DIN rail fuse holders and fuses, or four breakers.
I like that it has a grounding bar, bus bar and the breakers. But I already have the y connectors and i have planned out the inline fuses. I wasnt sure if i needed this. But it sounds like i dont. It sounds like it would be redundant.

i will screw things to a board on the wall. The charge controller, the fuse before the charge controller. This will be a 50amp fuse. Would this circuit breaker be ok:
 

Forbisher

Փփքխմպձժճֆըվմ
Joined
Feb 3, 2020
Messages
2,582
Location
Էթփձ
What is your configuration of the panels? 5s2p, 2s5p?


its not configured yet. They will be soon though. I had been thinking 3s4p. Do you think it would be better to 67V
5s2p or 2s5p? I have 4 12v batteries which I am setting up 2s2p. My charge controller is 12/24v and it is 40a. My inverter is 24v and is 2000w.
**************
Isn't your 40A SCC a Renogy 100V max input?
3S 4P is your best choice for 12 panels.

5S2P is only 10 panels and over your 100V max input.

If you had bought a 150V input SCC then for 6S2P you would have not needed fuses.
 
Last edited:

Tbleppy

New Member
Joined
Feb 4, 2021
Messages
83
What is your configuration of the panels? 5s2p, 2s5p?


its not configured yet. They will be soon though. I had been thinking 3s4p. Do you think it would be better to 67V
5s2p or 2s5p? I have 4 12v batteries which I am setting up 2s2p. My charge controller is 12/24v and it is 40a. My inverter is 24v and is 2000w.
**************
Isn't your 40A SCC a Renogy 100V max input?
3S 4P is your best choice for 12 panels.

5S2P is only 10 panels and over your 100V max input.

If you had bought a 150V input SCC then for 6S2P you would have not needed fuses.
that would have eliminated the need for fuses between panel strings. All other fuses would still be necessary, if I am correct.

i have the inline fuses figured out. It is the 50a fuse before charge controller im trying to figure out. Can you tell me if this would work or show me a good one please:

 

Hedges

I See Electromagnetic Fields!
Joined
Mar 28, 2020
Messages
8,363
Either Blue Sea or Bussmann is a good brand. So long as the Amazon vendor is selling an authentic part not a knock-off (many of that style from no-name manufacturers which don't meet their specs.)


"INTERRUPT RATING 3 kAIC"
This means it can interrupt a short circuit up to 3000A, which is what a car battery produces.

I think you are using a LiFePO4 battery (which I think can deliver 10,000 to 20,000A into a short), so I don't think this breaker is good connected directly to the battery. If there is suitably rated over-current protection (e.g. a class T fuse) on the battery and this breaker is downstream, then maybe OK.

https://diysolarforum.com/threads/1000watt-panel-system-with-10-100watt-panels.18174/#post-210531

Is this a 24V battery and 40A charge controller? If so, 50A is a good size breaker between them.

On the input, you have 3s4p, 4 strings of 3 panels in series. 5.7A Isc so 23A total. Wires should be sized to handle 1.56x that much current. No breaker is required, and a 50A breaker simply serves as a switch, will never trip due to over-current.

Both Blue Sea and Bussmann say 48VDC. One of the pictures shows a breaker which says 42VDC; that makes me suspicious.

Your string of 3, "12V" panels will be 68Voc, so these breakers aren't suitably rated for use on the PV panel side.
 
Top