Ground mount panels . What are my options.

[Dmitry]

I had a guy from solar city two years ago to come and do assessment . My roof was not in ideal positioning and was shaded with large trees that I have no intend to take down soon. he said that they don't do ground installation at the time.
I cleared and leveled some land recently and thinking about my options. Have couple questions.
Does distance from the house play important role?( Like increasing price of installation and producing power loss).

What are the options with connecting wires? Do they have to be underground completely or I can bury part of the run close to the house?

What is ideal positioning ? Is it strictly south?

 

[Where2]

Have couple questions.
Does distance from the house play important role?( Like increasing price of installation and producing power loss).

What are the options with connecting wires? Do they have to be underground completely or I can bury part of the run close to the house?

What is ideal positioning ? Is it strictly south?

Copper wire isn't inexpensive. Aluminum wire can be problematic. The further the array is from the house, the more expensive the wire component gets in the installation cost. To combat wire resistance (wasted energy), you either have to upsize the wire, or step up the voltage to cover more distance. Stepping up and stepping down voltage isn't a recommended concept when you're talking about a grid tied residential PV array.

I don't think any part of the NEC says the wire cannot be exposed. If you intend to suspend the wires, you have to select the appropriate type of wire with the appropriate insulation (sunlight & oil resistant) from the NEC book, and make sure you support the wire properly. You also have to expect exposed wire has a finite life, and may need periodic maintenance in a climate subject to snow and ice. Personally, I hate having to watch overhead wires when working on my properties. If I do a ground mount at my farm, the wiring will be underground. If I hit ledge before I get the wire conduit and foundations to the proper depth, that's where a few truck loads of fill come in.

Ideal positioning depends on your location. In the northern hemisphere, facing south. In the southern hemisphere, facing north. On the equator, facing up. Then there's tilt angle, and once you get into that you might as well break out the NREL Red Book. Since you're in CT, I'll direct you to the NREL page of CT data:
http://rredc.nrel.gov/solar/pubs/redbook/PDFs/CT.PDF

 

[Dmitry]

is there any disadvantages for ground installation over roof mounted system?

 

[Highbeam]

Graffiti. Mower thrown rocks. Bonking your head. Theft. Aluminum wire is excellent these days, back in 1950 not so much.

 

[georgepds]

" The further the array is from the house, the more expensive the wire component gets in the installation "


Microinverters take care of this problem if the installation is grid tied

Wire to the panels is 240v ~4amp per dc kv installed.... Not much at all.

 

[peakbagger]

Ground mounts can be optimized for angle. Ideally you generally set the angle at your latitude. If you go with adjustable tilt panels you can gain about 10% yearly production as long as you move them. They are a heck of lot easier to clear snow off and have an increase in performance as they are operate at a lower temperature then a roof. There is a limitation that unless you have a sloped lot or spend a lot of money to elevate the array that you need to account for shading on one panel by the panel in front of it. If you optimize the angle for summer production like commercial solar farms it not an issue but is an issue if you want to winter production.

A ground mount array doesn't need to comply with the new rapid disconnect rules (non issue if you go with microinverters). Of course in theory if you don't have shading issues, then no need to waste the money on microinverters and just go with string inverter in the basement so you can run a high voltage home run wire from the array to the house which allows a smaller gauge wire.

As the prior poster mentioned ground mounts can be exposed to more abuse. Some inspectors may require a fence around the array even though netting is legit on the back of the panels for protection of the wring. A ground mount array will cost more as it has more steel then a roof mount.

 

[Where2]

" The further the array is from the house, the more expensive the wire component gets in the installation "

Microinverters take care of this problem if the installation is grid tied

Wire to the panels is 240v ~4amp per dc kv installed.... Not much at all.

There's still voltage drop with microinverters... I've got 20 Enphase M215's on my roof, and I am the guy who ran the calculations on voltage drop from the second floor attic mounted terminal block wiring splice panel to the double breaker PV disconnect panel on the ground floor, outside in the middle of the house.

Southwire and many of the other wire manufacturers have very convenient voltage drop calculators available online.

We could take this out of the hypotheticals if the OP could provide some sort of approximate wire routing distance between the potential ground mount location and the service panel on the house where the electrical connections would be joined. The known distance should include differences in vertical height, since some people have considerable vertical relief to their properties, increasing the wire length required.