John Sheridan
Member
I want to build a system soon and want to have at least 1000 watts worth of power, so 200X6 panels.
From what I reads and watch on the youtubes, you take all the positive and negative wires and connect them together separately and then you connect them to the positive negative inputs on the charge controller, what method to go to a single cable for each positive and negative wires to connect to the charge controller is best ?
Just new to solar and just trying to understand.
johnmath
Member
John, there isn't a single or even simple answer to your question without a lot more information about exactly what you are trying to achieve.
Will it be on of off grid?
Will you have battery storage?
Will you run predominantly low voltage wiring with an inverter for only appliance that must have 240 volts, or do you want to reticulate power at 240 volts only?
Are there any shading issues where some panels might be shaded while others aren't?
Will you have any other sources of backup power? Wind? Hydro? Mains? Diesel?
What is your anticipated daily energy requirement? What time of day will you use most power?
All of these things will factor in to your design decisions to set the optimum and cost effective array voltage and configuration, etc.
Chippa2014
Member
Hi John,
The only recommendation I have, additional to JohnMaths, is to research on connecting "in Series" and "in Parallel".
JohnMaths response is where you need to start. Once you know what your connecting to and the type of inverter and its input voltage, you can then determine how best to meet that requirement.
This may help explain 
cheers
wlb
Member
John Sheridan said:
I want to build a system soon and want to have at least 1000 watts worth of power, so 200X6 panels.From what I reads and watch on the youtubes, you take all the positive and negative wires and connect them together separately and then you connect them to the positive negative inputs on the charge controller, what method to go to a single cable for each positive and negative wires to connect to the charge controller is best ?
Just new to solar and just trying to understand.
John,
You seem like an enthusiastic person who is keen to have a go and would like to do it all yourself. I mean no disrespect when I say that you seem to have been going around in circles for the past 12 months due to a lack of understanding of the basics of electricity. This isn't meant as a criticism. We all lack basic understanding in many areas. Unless you can answer all of Johnmath's questions, understand why he asks them, and then understand his responses based on your answers, you are very likely to make some expensive or dangerous mistakes; or simply just waste a lot of effort and be disappointed in the results.
My advice would be to use this forum to get recommendations for off-grid experts in your area; people with whom you can have a face to face chat.
Beware of YouTube and Google. Unless you have a basic understanding of the concepts involved, you're not in a position to separate the wheat from the chaff - and there is an awful lot of chaff. YouTube in particular can easily mislead. Just because you see something being demonstrated, doesn't mean it's real. There are plenty of YouTube clips that 'prove' perpetual motion, for example.
You really need to talk to an expert, face to face, and work with them to design the system you need. This may cost you a fee; it may not.
So see if anyone can recommend someone in your area.
John Sheridan
Member
Yes it will be off grid.
Would be a 12 volt system with Trojan L16 6 volt battery's connected up to keep everything 12 volts with the 6 battery's or so, I think that's a series/parallel setup.
Though batteries and panels are still not decided, just throwing some ideas around.
Well that's my thinking, just throwing around ideas at the moment, when it comes to making the decisions for reals, will get a pro to help me out.
I do want to get a couple 220 ah battery's and hook them up to my 120 watt panel for my car, when I get it and slap in a 500 watt inverter in the mix as well, that system should be much easier to setup, and would do me fine power wise before I build the bigger system.
Thanks all.
johnmath
Member
12 volts is a low voltage for a 1000 watt system, which means high currents and thick cables. Maybe you should think about a 24 or 48 volt system, to halve or quarter currents, and hence cable thickness requirements. 48 volts is the highest to consider fir a safe DIY system IMHO.
Whatever you decide as the system voltage, I would suggest getting panels at a matching voltage with individual charge controllers paralleled to your batteries. The higher the voltage of your battery system, the thinner the wires to the PVs can be. 200 watts = 16.7 amps at 12 volts, 8.3 amps at 24 volts and 4.2 amps at 48 volts.
Normally, you would use ~18 volt panel for a 12 volt battery, ~36 volt panel for a 24 volt battery and ~72 volt panel for a 48 volt battery. The charge controller matches the PV to the battery.
So if you wanted 5 or 6 x 200 watt panels, say 1000 watts, that's 83 amps at 12 volts, 42 amps at 24 volts or 21 amps at 48 volts. The current makes a huge difference to the size and cost of your cables.
r2160
Member
John, to give you a bit of a basis of amps:
if we want to draw 1000w here are some rough calculations:
1000w at 12v is 83.3 amps
1000w at 24v is 41.6 amps
1000w at 48v is 20.8 amps
Moving 20 amps is a lot simplier and easier than moving 80 amps.
P = VI (P is power in watts, V is voltage, I is current in amps)
That is why many people here are suggesting 48v. However, before you start, it is important that you consider exactly what you want to achieve first.
Hope this helps
Glenn
John Sheridan
Member
I am not really bothered about the size of my cables, I can get 0 gauge 25 meters for 437 dollars, 25 meters is enough for my system I would think, can double the length if necessary and it would be only 870 bucks for wire, the wire wont wear out and can use it for other things if necessary, other systems even.
I am a little in the dark on how you ad up the amps on a solar panel array, do you use the normal amp rating or the overload short rating, what do they usually call it that I need to use.
Just trying to figure out how many panels I can use, would want to use a 40,50,60 amp charge controller, but not sure how to add up the amps from the panels.
going to be a while will I put it together, but getting there, I think I have the KWH,AH maths ok, well how much power I will have and how much I will be using, I think maybe 1.5 to 2 KWH a day and I would have like 9000 KWH to use before I discharge my battery's 30 to 40% from full.
12 X 225ah batterys.
David
Member
John Sheridan said:
I am not really bothered about the size of my cables, I can get 0 gauge 25 meters for 437 dollars, 25 meters is enough for my system
Expensive for the size. Anyway you should really be using metric not AWG this is Australia afterall.
John Sheridan
Member
Whats the metric for 0 gauge
I don't know why people keep scrimping on the cables, I find that to be the least important thing, get decent cable, better than you need even, be done with it, much more to worry about in your system than cable
