4 panels to grid tie. 8 cables or 2 big gage ones.

[telpoch]

Hi All..

I'm completely new to this forum and to solar systems... But very excited.

I have a questio, I'm sure it's an easy one for you...

I have 4 230 watt panels I intend to connect to 1 grid tie inverter in parallel. My first question is: Do I need to run 8 cables (10 gage, aprox 30 - 40 feet each) or is that a waste and I shuld run only 2 sets, or, what's recommended for this situation?

If less than 8 wires will be used, should I get branch connectors?

How OK is it to not use MC4 connectors and solder and isolate cables oneself?

Any comments about the length, quantity, gage, and all that, or about anything else, are greatly appreciated.

Thanks!

[Sunking]

Unless you are using microinversters all your panels will be in series as most GTI's minimum voltage is around 200 volts.

[telpoch]

It is a micro inverter, takes from 28 to 56 or so volts... I'm in Mexico and hope to not have any issue with the electric company regarding US norms.

The particular GTI is a Power Jack 1200..

Thanks a lot for your kind response.

[Elkhornsun]

Start with the voltage produced by each panel. The greater the voltage the smaller the cross section of the cable can be for any given distance. This is why unless shading is a problem it is better to wire the panels in serial to increase the voltage and decrease the current loss through the wires. Think of a 12v battery in a car with its 4ga cables to the starter motor as compared to the 220v wires to an electric cooktop which are 12 gauge.

Another way to look at it is to assume each panel produces 6 amps so you have in total 24 amps produced. With a 0.3% current loss you would be limited to a 4' run with 12ga cable but can go up to 16' (5 meters) with 6ga cable.

Many small charge controllers cannot even accept a direct connection of 6g wires as the expectation is that the panels will be connected in series to keep voltages between 250 and 600 volts in the USA.

[telpoch]

Thank you so much for your reply, it makes a lot of sense. Also, please forgive me for taking so long to reply.

Here is a question/How crazy is this idea:

Since my inverter is rated from 28 to 52 volts and any 2 of my panels could exceed that max, What if I installed the inverted very close to the panels, on the roof, on it's own isolated, shaded and ventilated case and used 10 gage short cables to connect to it, and then use also 10 gage from the inverter to the nearest wall plug?

Thanks again!

[inetdog]

Thank you so much for your reply, it makes a lot of sense. Also, please forgive me for taking so long to reply.

Here is a question/How crazy is this idea:

Since my inverter is rated from 28 to 52 volts and any 2 of my panels could exceed that max, What if I installed the inverted very close to the panels, on the roof, on it's own isolated, shaded and ventilated case and used 10 gage short cables to connect to it, and then use also 10 gage from the inverter to the nearest wall plug?

Thanks again!

Using the PowerJack inverter, you are probably better off putting it outside in an enclosure which is also fireproof, so that when it melts down it will not set your house on fire.
A problem with devices which carry no UL or other approval is that you have no idea whether any given unit was designed and assembled properly using proper components.

Many different brands of Chinese-made small grid tie inverters appear to be sharing exactly the same circuit boards, but the delivered product varies wildly from one to another and from month to month.

[telpoch]

The whole house is made out of concrete/brick/stone, but sure enough that's another good reason to keep it outside

[green]

... from the inverter to the nearest wall plug?

Telpoch make sure this thing is on it's own dedicated circuit, meaning absolutley nothing else on the same circuit. There is a real danger of overloading the wires in your wall if you backfeed on a circuit that is running a bunch of other things. That is why professioanly installed systems are always connected to the circuit breaker panel into their own circuit.

Good luck,
Green

[telpoch]

I live where I may not find any professionals that know how to install these things, so please forgive me if I ask a bit too much. Just trying to understand how to do what you just suggested.

When you say this inverter needs to be connected in it's own circuit, will this requirement be met if I connect it directly to the main braker box in my house? Before the fuse? After the fuse?

Thank you so much for your help.

[green]

Do not mess with your breaker box or fuse box if that's what you have. Leave that to the pros. You can get hurt or killed if you don't know what you are doing.



Please do not do any electrical work you are not capable of. It's not worth it. You could get seriously injured or die. When in doubt get a professional to help.

Stay safe,
Green

[telpoch]

Now it makes more sense.

I appreciate your concern also. While I'm not an electrician I understand the dangers and how the wiring works. I wasn't sure about what you meant, but now I understand.

I already added a plug box directly to the fuse box, before the fuses, which I use to plug my welding machine. For what you say though. I should not use that plug box for the inverter at the same time as the welding machine.

Thanks again for being so patient.

[Naptown]

Now it makes more sense.

I appreciate your concern also. While I'm not an electrician I understand the dangers and how the wiring works. I wasn't sure about what you meant, but now I understand.

I already added a plug box directly to the fuse box, before the fuses, which I use to plug my welding machine. For what you say though. I should not use that plug box for the inverter at the same time as the welding machine.

Thanks again for being so patient.

If the statement above means you connected the plug to the box and it is not fused where it is connected this is a big problem.

[telpoch]

It's pretty common around here to plug welding machines directly to the street before the fuses. I know it's not a best practice, but it's, again, very common.

I'll make sure to connect the grid tie after the fuses in it's own circuit...

Thanks!