Cant find an electrician, so i need help

[bucklesfriendly]

Electricians are so hard to find in rural maine!!
I have 12 q cell 340s already mounted to my roof. They're about 60 feet from the house sub panel. The Main panel is about another 40 feet away in the garage. I don't know why it was done like that; the CBs inside only run the garage and the house sub panel.
May I mount he inverter next to the sub panel? Running the wire from the sub panel to the main panel is beyond me; 2 crawl spaces and a concrete slab.
Should I use a combiner box?
May I hook the panels together when its light out, or would/could that lead to a shock?
When I run the wire from the panels to the inverter, or combiner box, may I run them next to each other? I worry they'll heat up in proximity and may cause a fire.
I won't hook up the inverter to the CB panel, but I WOULD like to mount it. Maybe the electrician will come out if they think its an easy job.
Thanks from the noob!
C

 

[Shimmy]

Not ideal; how many amps is the sub-panel?

 

[FilterGuy]

Let's get a few more details

• How are the panels wired? (I am guessing there are either 2 strings of 6 or 3 strings of 4.)
• What kind of inverter are you planning? Is it 240V or 120V output? From the description of what you are doing, it sounds like a grid-tie string inverter.... but that is just a swag.
• What is the rated current of the sub-panel?
• What is the value of the breaker in the main panel that feeds the sub-panel?
• What size wires are between the sub-panel and the main breaker?
• Does the installation need to be code compliant?

Should I use a combiner box?

When I run the wire from the panels to the inverter, or combiner box, may I run them next to each other? I worry they'll heat up in proximity and may cause a fire.

Whether you need a combiner box depends on the configuration of the panels.
If properly sized, you can run the wires next to each other.

This resource may help you answer both questions.

Fusing & Wire Sizing guidelines for solar panels

To get the paper, click on the orange'' button at the top of the screen. This resource is intended to help the user understand when they need to add Over Current Protection Devices (OCPDs - Fuses or Breakers) to the solar panel array and what...

diysolarforum.com

May I hook the panels together when its light out, or would/could that lead to a shock?

Yes, but extreme care must be taken. I assume there are MC4 connectors on the panels. These are reasonably safe to handle while hot. However, at the inverter, you are likely to be dealing with bare conductors. Consequently, You will connect to the inverter first. After that you will wire the combiner box if you have one. Only then will you start energizing the circuit by plugging the MC4 cables together. Do *not* plug in the panels and then try to wire them to the inverter.

May I mount he inverter next to the sub panel?

I am going to assume you are talking about a 240V grid-tie string inverter.... If not, please do not follow any of the following!!!

If this is going to be a code-compliant install, there are a *lot* of requirements that must be met.

* It is ok to feed into a sub-panel, but both the sub-panel and the main panel must meet the 120% rule that states the sum of all of the input power sources must not exceed 120% of the panel rating. As an example, if the sub-panel is rated for 100A and the breaker feeding the sub-panel is 100A, you can only feed an additional 20A of power from the inverter. You have 12 x 340W = 4080W of panels. If the inverter is outputting 240V then it would be 4080/240V=17A so it would be OK for this example.

* The wiring between the main panel and the sub-panel must be large enough to handle all of the solar. You will probably be OK on this, but check.

* There are both AC and DC disconnect requirements. The breakers in the sub-panel may meet the AC disconnect requirements but you will definitely need a DC disconnect switch on the PV side that disconnects both the positive and negative.

* There are accessibility requirements for the disconnects. I have not looked at this in great detail so you should do some research, but the disconnects man need to be placed on an outside wall

* There are a lot of labeling requirements that must be met at both the sub-panel and the main panel. Please look those up.

 

[Hedges]

I prefer to run distance with high-voltage PV string, because losses are minimized and don't impact performance beyond percentage losses.

You have to understand safe handling of electrical circuits, how to determine if they are energized or not, if making a connection will cause current to flow (or if breaking will interrupt it, pulling an arc.)
You have to design and analyze any series/parallel arrangement to ensure voltage and current are within spec, so as to not cause failures or hazards.

Model numbers of equipment, data sheets, block diagrams and maybe schematics would be a good start.

Wires close to other doesn't generally represent any hazard, although many in a bundle can't carry as much current per wire without overheating due to poorer cooling.

PV panels produce hazardous voltage (and enough current to cause injury) in very low light. The MC connectors make them safe to handle, except or unplugging with current flow. The trick is to make other connections with panels disconnected, open any switches, then make connections. After panels have been connected to an inverter (or just AC connected), its PV terminals may have high voltage. Always shut everything off, wait the time instructions say to, measure to confirm zero voltage.