Author Topic: Seeking Specific Solar Knowledge  (Read 1343 times)

Surveyor1

Seeking Specific Solar Knowledge
« on: September 14, 2021, 04:39:14 PM »
I just installed 8 250 watt solar panels (specs included below).  I was planning on utilizing a 4 to 1 parallel branch Y connectors (link below) for each set of 4 panels and running these 2 sets to a 2 to 1 parallel branch Y connector (link below) going to an 80 amp charge controller (link below)

I have a distinct feeling that I cannot do this without burning something up. If I cannot hook what I have this way I would definitely listen to a hey RWS how would you hook this up if you were doing this on your house as a backup?  Im trying to keep cost down but simply put, you cannot put a price on safety!  Any input on correcting my design flaws would be greatly appreciated!  Thanks in advance!

https://www.amazon.com/gp/product/B083KN9H22/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B07B4ZM8Y8/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B0753X68PS/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1
Give a man a fish and feed him a day teach him how to fish and you have a friend for life.

RWS

Re: Seeking Specific Solar Knowledge
« Reply #1 on: September 14, 2021, 05:47:13 PM »
The NEC says.  Each panel or series string of panels must be fused.  The fuse size listed on the data on the back of your solar panel.  So if you have 2 series strings of 4 (8 panels), you need 2 fuses.  I use a combiner box with 2 circuit breakers.  Remember NEC says you can only have 80% of the rated current value of your fuse or CB.
https://www.solar-electric.com/mnpv3.html
Under Product Documents, download the installation manual.  Tells you how to install it.
You are not protecting your equipment from the power from the panels.  You are protecting the panels from reverse current should something in your charge controller go bad.  Keeps your solar panel from catching fire.  Fuse size on your panel data plate says 15A.
https://www.solar-electric.com/mnepv.html    from the drop down select 15A.

Surveyor1

Re: Seeking Specific Solar Knowledge
« Reply #2 on: September 14, 2021, 07:44:23 PM »
Thanks RWS!

I guess I will hire a solar company.  I speak fluent dumbass redneck and get answers from engineers that think that everyone else is an engineer.  I am smart enough when I know that if I think I need to punt, I actually punt!!!  I know that for people that understand this stuff that its easy!  I also am smart enough that if it seems like people are speaking Japanese to go hire a Japanese interpreter.  I will be hiring a professional to finish up my system instead of learning Japanese and burning my house down to save a few hundred bucks!  I know what Im asking is second nature to many but not to me! 

My 12 volt DC system, say peasy!  Ill let yall know how the rest of my system turns out!  The biggest problem of hiring a solar company to come in to rural Georgia is they usually have to come from a long way away.  Thats still much better than the local volunteer fire department! 
Give a man a fish and feed him a day teach him how to fish and you have a friend for life.

RWS

Re: Seeking Specific Solar Knowledge
« Reply #3 on: September 14, 2021, 08:41:52 PM »
If you live in NW Ga., John Gault might be able to help you.  See members list.

Fixit

Re: Seeking Specific Solar Knowledge
« Reply #4 on: September 15, 2021, 07:44:57 AM »
Solar has become common enough now that you probably have a local electrician that has done some installation.  Find him by asking questions of the electrical inspector .  Of course this is the view from here where in a 3 county area there are over 500 solar systems and may of those are not grid tie systems.

nj_m715

Re: Seeking Specific Solar Knowledge
« Reply #5 on: September 15, 2021, 10:45:54 AM »
your charge controller has 48v PV input
thats only one panel

you have to come off the roof at 37v and 70 amps
70 amps requires massive wiring

picking a controller with a higher input might be better

if you can double the voltage, you would cut the amps and cut the wire size needed

https://www.windynation.com/jzv/inf/choosing-right-wire-size





Surveyor1

Re: Seeking Specific Solar Knowledge
« Reply #6 on: September 15, 2021, 11:01:01 AM »
Thanks NJ!  All advice is appreciated!
Give a man a fish and feed him a day teach him how to fish and you have a friend for life.

Surveyor1

Re: Seeking Specific Solar Knowledge
« Reply #7 on: September 15, 2021, 11:04:48 AM »
your charge controller has 48v PV input
thats only one panel

you have to come off the roof at 37v and 70 amps
70 amps requires massive wiring

picking a controller with a higher input might be better

if you can double the voltage, you would cut the amps and cut the wire size needed

https://www.windynation.com/jzv/inf/choosing-right-wire-size

Maybe I misunderstood the specs?  I thought that 48 volts was max for one panel not the whole controller?
Give a man a fish and feed him a day teach him how to fish and you have a friend for life.

nj_m715

Re: Seeking Specific Solar Knowledge
« Reply #8 on: September 15, 2021, 11:48:12 AM »
it doesn't care about one panel, it cares what you plug into it

one panel at 48v is 48v
or plug in two panels at 24v - still 48v
or four panels at 12v - still 48v
no difference to the controller it only cares that it's not over 48v so it doesn't burn up

hopefully I explained that right

the cheap all in one bought has 80v pv max and 50amp max
so I can run 10 panels set up in 5 strings of 2 panels
that gives me 74volts and 45amps to max out my controller

I probably would install 8 like you did
I can combine 2 series (74v) and 2 parallel  (18amps)

and come off the roof with 2 pair of 12ga or 10ga wire, if i can keep my run short enough






Surveyor1

Re: Seeking Specific Solar Knowledge
« Reply #9 on: September 15, 2021, 01:22:02 PM »
Thanks great input!
Give a man a fish and feed him a day teach him how to fish and you have a friend for life.

ProGeek

Re: Seeking Specific Solar Knowledge
« Reply #10 on: September 16, 2021, 06:35:57 PM »
It's all about how you wire it. Series or Parallel. Panels are the same as batteries.  https://understandsolar.com/solar-panels-in-series-vs-parallel/ In series + to - to + to -, you increase voltage but not amps. This is like batteries in a flashlight that are end to end. In parallel it's + to + and - to -. The voltage stays the same and amps go up. I would recommend you get a new controller that will take at least 140V input so you can wire all 4 panels in series with reasonable sized wire. You also need to account for all that power going into and out of batteries. You didn't mention any battery bank?
If the freedom of speech is taken away then dumb and silent we may be led, like sheep to the slaughter.

 

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