Setting up a Main Electrical Panel

[loarrh]

Getting ready to pour a foundation for my house next week. I would like to make sure that my Main electrical panel is setup so that when I install RE next summer, the electrical panel is ready to go. I would like to get sufficient details that I can provide to the electricians for qoutes, and installation. Would sure appreciate it if someone could point me in the right direction, or provide details on how to do this.

Any other tips or suggestions that I should do now, before the house is built, to make RE installation is easier/better/cheaper?

Thanks so much.

[andrewc]

There really isn't a whole lot to prepare for. Solar installer are used tying into existing services. The biggest thing I can think of is this. The most common method of residential solar connection is backfeeding a breaker. To do this, you a) need the physical space in the panel board to do so, and b) need to size your solar breaker based on the 120% rule, which goes like this. The combined amperage rating of all connected sources of power cannot exceed 120% of the amperage rating of your panel's busbar. An example, if you have a 200A busbar with a 200A main breaker, you only have room left for 40A solar breaker. So assuming backfed breakers are allowed in your jurisdiction, and that is the method that your future solar installer will be using, the main consideration would be making sure you have a large enough busbar in that panel, and that you leave open space at the end of the panel furthest from the main breaker.

[peakbagger]

If you are ever thinking of a generator it isnt that much more money to get a main panel with a main breaker than can be interlocked with a generator breaker. Unless you plan on huge solar system the prior posters comment about 40 Amps on a 200 Amp panel is right on. Most inverters output 240 VAC into a double breaker. Make sure you have some extra space in the panel for extra breakers (they normally do)

I would run a metal conduit 1" from attic to the basement in a wall as if you go with a roof mount array you need to run the wires down to the inverter in metal conduit. If you ever are considering solar hot water run two insulated 3/4" copper lines with a 3/4" metal conduit from attic to roof. This will cover you if you want to go with a DC PV pump fed by a solar panel. Even if you go with an AC pump you still need a conduit as usually temperature sensor run from the roof to the controller in the basement.

I am a beleiver in WR grace storm shield under the shingles where the PV panels will go. When you install the mounting brackets, this stuff will seal up any holes. It will extend the life of the roof considerably, under the panels out of the sun I would expect 40 years.

[Sunking]

For electrical not much to prepare for. Assuming you go with a standard 200-Amp Single they normally come equipped with 42 circuit poles. You just need to reserve a Two-Ganged pole position for the future breaker. Should be no problem if you do not have electric hot water and cooking. About the only thing electrically is make sure your EC stubs you up some re-bar out of the slab for a Ground connection and make sure he uses the required cement encased electrode in the concrete slab.

Mechanically if this is the initial build have the roofers go ahead and install the racking system for the panels. I cannot stress this enough as it will in all likely hood eliminate chances of a roof leak later.

[billvon]

If you are ever thinking of a generator it isnt that much more money to get a main panel with a main breaker than can be interlocked with a generator breaker.

Who makes these? I've seen the Generac panels that give you a transfer switch, but no "conventional" panels that come with an option for source transfer.

[inetdog]

Who makes these? I've seen the Generac panels that give you a transfer switch, but no "conventional" panels that come with an option for source transfer.

It may not be an official option but rather a design feature.

If the main breaker is in the same rows as the individual circuit breakers, rather than being separated from them, then you can put the main breaker and the alternate source breaker opposite each other horizontally and use a mechanical interlock between the two sets of handles. (Commercially available.) It just will not be automatic.
If the main is separate, you can still do a mechanical interlock, but it will be more complex to configure and may have to be custom fabricated.

Unlike a grid-tie where you would want to put the inverter breaker at the opposite end, for a non-simultaneous connection without a separate transfer switch, you want them at the same end.

[zehutiiman]

I was searching for an answer to my question, unsuccessfully, so I hope you don't mind if I piggyback onto this thread:

In my system, I'll have two branches (total of 20 M215's at 0.9a each) running to a subpanel with two 20-amp double breakers. When I run a line from the subpanel to the PCC, am I correct in thinking that I only need a single 25 or 30-amp double breaker in the main box (18a x 1.25 = 22.5a)? And, yes I'm going to have an electrician sign off on the final product

Thanks,

Mo

[rick1]

Use a 200 amp box with a 225 amp buss bar. This will allow three 20 amp circuits of solar. Have electrican run wires from panel to outside of house where solar is coming in and mount a box there. Then rough in 50 amp wiring for two electric cars in garage.

[Naptown]

Use a 200 amp box with a 225 amp buss bar. This will allow three 20 amp circuits of solar. Have electrican run wires from panel to outside of house where solar is coming in and mount a box there. Then rough in 50 amp wiring for two electric cars in garage.

Wrong
I suggest you read and understand Article 690 before giving any more advise on how to connect solar in a grid tie system.

A) you are making an assumption on the rating of the buss bars.
B) Maximum you could feed a panel with 225A buss bars is with 45 amps.
C) Why would you need 3 circuits for a total of 20 M215's? Two are all that are required and still leaves room to add another 14 panels. This will also not exceed the maximum feed in on a 200A panel.

So the correct way to do this is to run 2 20A circuits from the inverter strings to the panel. If your utility or AHJ require a disconnect next to the meter install a 4 circuit weatherproof panel outside. Then run a 40A cable ( The enphase circuits are already maxed out at 80% to account for a continuous load) and tie that into the panel end opposite the main breaker.

Since you know so much what is the maximum amount of amps you can feed into a 200A service.

[rick1]

Wrong
I suggest you read and understand Article 690 before giving any more advise on how to connect solar in a grid tie system.

A) you are making an assumption on the rating of the buss bars.
B) Maximum you could feed a panel with 225A buss bars is with 45 amps.
C) Why would you need 3 circuits for a total of 20 M215's? Two are all that are required and still leaves room to add another 14 panels. This will also not exceed the maximum feed in on a 200A panel.

So the correct way to do this is to run 2 20A circuits from the inverter strings to the panel. If your utility or AHJ require a disconnect next to the meter install a 4 circuit weatherproof panel outside. Then run a 40A cable ( The enphase circuits are already maxed out at 80% to account for a continuous load) and tie that into the panel end opposite the main breaker.

Since you know so much what is the maximum amount of amps you can feed into a 200A service.

yOU CAN FEED 40 AMPS IN A 200A SERVICE WITH A 200 AMP BUSS BAR.

.89??? amps per M215 x 17 per string = about 16 amps per 20 amp breaker.
16 x 3 = 48 amps just a little over the code recomindation.
With a little fugging and some line losses this allows 51 enphase M215 in one 200amp box with 225 amp buss bar.

You know he might want to add to his system later and there is no reason to run heavier wire later. I have three 20 amp 240 volt circuits and two 10 amp 120 vlot circuits to power tools and the Envoy at the array.

[russ]

16 x 3 = 48 amps just a little over the code recomindation. With a little fugging and some line losses this allows 51 enphase M215 in one 200amp box with 225 amp buss bar.

Forget the shade tree recommendations - keep solutions according to code and legal or don't post them.

[rick1]

ok if you want to be a legal eagle you can use two strings of 17 Enphase inverters and one string of 16 Enphase inverters = <45 amps.

[Naptown]

ok if you want to be a legal eagle you can use two strings of 17 Enphase inverters and one string of 16 Enphase inverters = <45 amps.

The code says the maximum of all OCPD feeding a panel buss is 120% of the buss bar ratings. Code does not address the actual amperage runnning on each circuit.

That said how many microinverters can be connected to a 200A 240V 1PH service?