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Aussiemike

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Posts: 24
Reply with quote  #1 

Hi Guys, Just joined a few minutes ago.
Was with another forum called Solar Panel Talk but felt like I was in kindergarten talking to university professors.
Thought I would try here before I made a complete fool of myself over there.

I am trying to install a small solar system on a plot I have on the coast of Tanzania.
I am actually living in Kenya but try to spend a week every month down there.
If you would like to see what I am dealing with please feel free to see it here.

https://web.facebook.com/Aussiemike.Tiwibeach/posts/1597822016963608 

Presently I am experimenting with 2 separate systems, one a small 12v to run my battery chargers , laptop and lighting.
I then have a 24v system which I am using for refrigeration.

Would someone be kind enough to let me know if the diagram below for 24v is ok or if it can be improved.

Cheers from Kenya
Aussiemike

solar diagram2.jpg 

 


stmbtwle

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Reply with quote  #2 
The layout looks good to me, as long as the wire size is big enough.

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Solar is like the wind. It may be free, but putting it to work isn't!
Willie, Tampa Bay
Aussiemike

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Posts: 24
Reply with quote  #3 
Thanks Willie, much appreciated.
Any advice on fuses/circuit breakers?
Cheers
Mike
SolarInterested

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Spam Stomper
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Reply with quote  #4 
Quote:
Originally Posted by Aussiemike
Thanks Willie, much appreciated.
Any advice on fuses/circuit breakers?
Cheers
Mike
Hi Mike. The two duplicates of this post were deleted. To combat spam the first five posts of new users have to be reviewed and approved by Admin before they're posted to the forums. As a result there may be delays before posts by new members appear. The delay should be short during the day but could be up to several hours overnight. Please be patient.(link)

You should have received an email from me with this notice when you joined. Once you acknowledge this post I'll delete it to clean up the thread.

Mike
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Both temperature rise and airflow are integral to comparing hot air collectors
stmbtwle

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Reply with quote  #5 
So THAT'S where the "spam stomper" handle comes from! Never thought of it before. 😀

Mike the way your system is drawn, I calculate about 34 amps max from the controller to the batteries and 17 from the panels to the controller. So to me that would indicate about 40 amp and 20 amp fuses/breakers, respectively.
Rick is the expert in that regard, maybe he'll come up.

Metric chart for wire size vs amps: http://www.ronhuebner.us/wire_sizes.htm

The output from the batteries to the inverter or fridge will require a different fuse, to be determined by the instructions for that device.

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Solar is like the wind. It may be free, but putting it to work isn't!
Willie, Tampa Bay
Aussiemike

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Posts: 24
Reply with quote  #6 
Much appreciated.
Would you be kind enough to explain your formula for the amps from the panels to the controller and the controller to the batteries. Really trying to get my head around all this.
Cheers Mike
stmbtwle

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Reply with quote  #7 
Watts = amps × volts. Or Amps = watts / volts. Or volts = watts / amps.

So for the panels, you have 4 12v panels in series totalling 800 watts, and 48v. 800 / 48 = 16.7 amps. Actually it will be less than that, the maximum amps (Isc) is on the back of the solar panel. In series configuration you add the volts, but the amps stay the same. In parallel configuration you add the amps but not the volts.

For the batteries, you have two sets of 2 12v batteries each. Add 2 12v batteries you get 24v. The other set is also 24v but they're in parallel with the first set so the volts don't add. So you still have 24v, more or less depending on state of charge.

The MPPT controller converts the output from the panels to charge the batteries. Call it magic.

The maximum possible charging wattage is 800 watts from the panels, so 800 / 24 = 33.3. Again, probably a bit less.

You can find books on the subject.



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Solar is like the wind. It may be free, but putting it to work isn't!
Willie, Tampa Bay
Aussiemike

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Posts: 24
Reply with quote  #8 
Hi Willie, Can't thank you enough for this.
Just one thing confuses me and that is watts in series.
I understand completely the series and parallel formula for batteries and amps but you are adding the watts and the volts. i.e. 4x12v=48v and 4x200=800w

"In series configuration you add the volts, but the amps stay the same."

Q. Are you saying that you can add watts together in series?

Q. Also if I am getting 16.7 Amps from the panels should I put a 20 Amp fuse on the positive line between the last battery and the MPPT controller and 50Amp on supply line to battery as in diagram attached?

Q.Do you think the panel setup versus battery setup are optimum or should I add to either one?

Greetings to Florida from Kenya
Mike

solar 24.jpg 

Aussiemike

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Posts: 24
Reply with quote  #9 

Hi Willie, I have done the reading you suggested and finally the penny has dropped and I understand.

I would still appreciate if you would cast your eyes over my diagram give it your blessing.
Cheers
Mike

stmbtwle

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Reply with quote  #10 
As long as the wire you choose can handle more than the fuses. Otherwise you risk a fire.
__________________
Solar is like the wind. It may be free, but putting it to work isn't!
Willie, Tampa Bay
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