Installation

System

Installing a 10mW ground/pole mount with Sunpower equipment. I have a contractor for the site prep, the concrete, the trenching and any finish/grading work.

30 panels, 10 per pole, one inverter per array or microinverters, open field, flat land, fully prepped including poles in concrete, 150' from the array to the house, 50' to the barn.

How many man days (PV installer and Electrician) would it take to install the system. No need for any equipment pricing.

I am thinking 2 PV installers for 2 days and 1 Electrician for 1 day.

How does that sound?

waynefromnscanada

Re: Installation

3 man-days to install and wire up 10MW of Solar? Your panels, if only 33 of them - - - - Hold on, somethings not adding up - - - how big are your panels?

BB.

Re: Installation

Guessing that the "m" prefix (mill; x 0.001) is being confused with the "k" (kilo; x 1,000).

But 10kW = 10,000 Watts / 30 panels = 333 Watt panels--a bit large...

So, still not quite understanding the setup.

You asked about Enphase vs Central Inverter types... With long power runs from the array to the meter/pole transformer. You can have problems with "voltage rise" if you have Enphase or Central inverters mounted at the arrays.

I would suggest looking at mounting central inverters near the utility meter... Especially if your utility voltage runs high at times (inverters will shut down if the utility voltage + rise >~260 VAC). Central inverters mounted near the utility drop (usually) have less of an issue with utility power that runs hot.

Although, one person here posted that Enphase reprogrammed the upper voltage limit in one installation... Not sure if I remember correctly, or if they do jack the voltage limit up in high utility+drop setups.

-Bill

System2

Re: Installation

BB. wrote: »

Guessing that the "m" prefix (mill; x 0.001) is being confused with the "k" (kilo; x 1,000).

But 10kW = 10,000 Watts / 30 panels = 333 Watt panels--a bit large...

So, still not quite understanding the setup.

You asked about Enphase vs Central Inverter types... With long power runs from the array to the meter/pole transformer. You can have problems with "voltage rise" if you have Enphase or Central inverters mounted at the arrays.

I would suggest looking at mounting central inverters near the utility meter... Especially if your utility voltage runs high at times (inverters will shut down if the utility voltage + rise >~260 VAC). Central inverters mounted near the utility drop (usually) have less of an issue with utility power that runs hot.

Although, one person here posted that Enphase reprogrammed the upper voltage limit in one installation... Not sure if I remember correctly, or if they do jack the voltage limit up in high utility+drop setups.

-Bill

Sorry 10kW system with Sunpower E19 320 (30 panels - staying just under 10kW due to additional state MA requirements). Utility voltage runs less than 235 and is very stable. Is it better to use microinverters instead of central in this application?

BB.

Re: Installation

With Enphase, you have to match to their approved panel list--So you are a bit more restricted in you choice of solar panels.

On the other hand, if you want add/replace a panel later, it is usually easier to mix/match an "oddball" panel in 5 years later when current panels are no longer available than a central inverter system.

There are theories that make it difficult to believe that Enphase inverters will last the life of the panels... So you may end up replacing inverters under each panel over the years vs replacing a central inverter on the wall of the home.

You should plan on a new GT central inverter every ~10+ years (my system is 6+ years old and I am on my 3rd inverter and second set of panels at the moment--but not much out of pocket cost for me at this point). How long will Enphase inverters last--No long term information on that.

In the end, this may be a cost/personal choice decision. At this point, Enphase seem to have been reliable to date with few (if any?) failures talked about here.

• 10,000 watts * 1/235 VAC = 42.6 amps
• 235 volts * 3% maximum drop = 7 volt drop
• 200' run of 4 awg copper wire @ 42.6 amps => 5 volt drop (~3% drop)
  
• 200' run of 1/0 awg copper wire @ 42.6 amps => 2 volt drop (~1% drop)
  

So, you are looking at a minimum of 4 awg copper wire run, if I understand your setup correctly.


Some people have used Aluminum wire for these longer runs--200' of 2 awg will give you 4.6 volt drop. You must use the proper copper to aluminum transition connectors to reduce the chances of corrosion/fire at the connections.

-Bill

newenergy

Re: Installation

Ground mount isn't terrible for micro-inverters since you can replace them fairly easily.

So far almost every micro-inverter installation I've done has had some trouble, and I've done 4 service calls on other people's installations. On the service calls, it was mostly shading issues that should have been obvious at the installation. (people think microinverter = shade doesn't matter, but putting a module in a place that is almost always shaded is still wasting that module) On my installations it has always been a problem with an inverter rather than a module and for the most part it has been just in the data reporting and not the power output. It can be a big hassle to diagnose the problem and a nightmare if it's in the middle of a roof mounted array.

On a ground mount, it's not such a big deal, but still, unless there's some compelling shading or orientation issue, I'd just set things up so that I can easily check the output from each string.