What do you think is cheaper?

oil pan 4

If I were to become a solar farmer what inverter voltage do you think is cheaper to work with?
480 volt 3 phase?
Or 3 phase 240v?

I'm thinking 3 phase 480v.
Since I can't find many 3 phase 240v units.

Tecnodave

Both will be uncommon......unless you are talking 25 horsepower or more 240 volt three phase will be more useful. Many inverters can be connected in a three phase setup but it is NOT 240 volt DELTA  HI-LEG three phase!  It is 120/208 WYE three phase.......To be clear on this.....240 DELTA  HIGH LEG THREE PHASE is COMMERCIAL....  120/208 WYE THREE PHASE is residential...I.e. large apartment complexes........there are DELTA-WYE Transformers   BUT make sure that the inverters can handle this configuration!  You are getting into engineering territory here unless you are a very skilled electrician.......FRANKLY.....you are way  over your head on this......Outback, MagnaSine, and  Cotek do support 120/208 WYE three phase and I think Schneider does as well but ask Dave Angelini on this.  Most inverters that are 120/240 volt only support a three wire connection......but with 240 DELTA......there is no neutral  on A-C phase or B-C phase  only on A-B phase will you have a neutral.....480 volt three phase is always WYE connected here in America.....Like I said this is ENGINEERS TERRITORY!

i don't like to be so blunt but unless very very qualified stay away from thoughts of this!  

BB.

You need to talk with your utility... Working voltage (and current/Wattage) varies by location and utility.

Also, the utility (their engineers) has to ensure they have capacity for your solar (and whatever your home/business loads).

Worst case, they may have not the infrastructure to carry those power levels and may refuse, or charge you, for the upgrade(s).

For example, many office parks in Northern California are wired for 120/208 "Wye" connections. When you get into 480 VAC--Are your only "loads" your solar generation? Do you have other local power needs (running home/business/etc.)?

And look at the various rate plans... For solar and normal loads. Commercial in California--It is complicated, and in the next few years you may see your solar rate plan(s) change--For residential, the utility only guaranteed a 10 year "grandfather" period. After that, who knows.

It is all dependent on your local utility and state politics (State Public Utility Commision). Some states have already effectively "shut down" new solar (Hawaii by prohibition, Nevada by "non-friendly" GT Solar Rate plans, and various local utility co-ops that have never allowed GT Solar across the country--As I recall...).

-Bill

Tecnodave

Most residential properties in California are served with 120/240 volt single phase. To upgrade to 120/240 Delta hi leg is a minimum of 1 year engineering time by the utility before planning the installation, the utility can charge you $10,000 for the engineering analysis. Adding 120/208 three phase requires changing the transformers on the utility pole, or adding new ones also on your bucks. I am adding a three phase to a commercial 120/240 split phase with PG&E pole only 125 feet away from the location, neighbor has a 480 volt 75 kW service, 5kv feeder lines overhead with lots of capacity but still I have to wait a year to get that third leg......rigged up a 40 kW three phase generator to run the three phase Equiptment that is nessecary for this business until Pigs,Goats, and Elephants gives us our three phase

hey don't blame me for that name the workers themselves named the company that....lol

david

BB.

Used to go to the PG&E cafeteria on occasion for breakfast with co-workers when working near their SF headquarters... Also known as going the the "zoo".

-Bill

Tecnodave

There  is a 30 kW residential installation in Felton CA that PG&E has stalled on for many years now.....the local grid there is not able to support that installation.....more than $100,000 engineering costs allready, solar is done but PG&E will not connect, homeowner did not get pre approval of the installation and it is now not usable for grid tie, utility refuses to upgrade local grid at their expense, why should they...they are the utility company...

oil pan 4

I have old 3 phase transformers on a pole next to my property for my well.
I believe they are wired for 480/277Y.
Wire thieves took the wire from the transformers to the dirt before I moved there.
This is in new mexico.
No one on the coop has an install like this so it would be done very closely with the electrical coop.

I may use the 480v service to power a small submersible well pump. Only talking like 1 to 3 hp.
Maybe an air compressor.

I'm working on 480v 3 phase motors and inverter drives almost every day at work. I'm used to it. 

Tecnodave

OK, you have expereince there, I don't want to see someone not expereinced with three phase wandering in there.
Most Ag wells over 25 horsepower are 480/277, if you allready have that keep it, don't know about utilities in New Mexico but Ag uses are grandfathered here in California ,  I do commercial electrical and I do have 240/480 transformers on hand used both three phase and single phase. Let me know, maybe we can do a deal or I might find one for you.  Talking about grandfathered......I service several dozens  480 volt floating installations, three wire, no neutral.......you cannot get that today but if it's grandfathered......I also have at least 2 or 3 240 volt floating three phase services and one corner grounded 240 volt delta three phase, no neutral, B phase grounded!  I was shocked to find it! That has not been allowed since the '30's or '40's  but they are grandfathered in, I can't even buy control boxes or change out services as I will have to upgrade entire service, these are very old farm installations. To repair some I have bought new Equiptment and gutted it to install the components into the original boxes. That is a repair, not an upgrade and I need no permit to do that......more of a technical troubleshooter than an electrician. Santa Cruz county is a bedroom community and there are many residential electricians here, only a few commercial electricians. But many farms, Watsonville is the strawberry capital of the world and Salinas is America's salad bowl...I'm in the middle of this so I pretty much do commercial shops and agriculture now. Homeowners first question is how much?  The farmers "can you get here now?"  I have never researched solar farming as it appears to be really big bucks that will get such installations approved .

david

NOTE:  my spelling is much better than Apples autobutchermyspelling .......hey I even taught my iPad to auto spell that! LOL!  Too bad it autobutcherspells common words

oil pan 4

Those are old school.
Probably delta with no neutral.

I like the setup I have. It's 3 transformers and I can see each line on each transformer for your hot and the opposite post on each transformer is tied together forming the neutral for each phase.

I probably won't make much money getting paid 3 cents a kwh and likely no taco breaks or credits.

Tecnodave

You are describing WYE connected for 480/277, that is the only was I have ever seen 480 volt done. At .03 per kWh it will be very difficult to break even, we're paying more like .27-.46 /kWh depending how energy efficient you are. We have a base line of several hundred kWh at base rate then you go up the tiers depending on your use, energy hogs during the summers heat pay near .50 per kWh but this is California, the land of regulate you to death, I haven't had a utility connection in years.
Floating delta has no neutral.....loads are phase to phase only, there is no 120 volts. Have you ever seen corner grounded delta......AKA Grounded B phase....no neutral .....phase to phase 240 volts .....A phase to ground 240 volts .....B phase grounded 0 volts...C phase to ground 240 volts.  No 120 volts, balanced loading only....very rare indeed, I found it on a farm feeding a 15 horsepower turbine pump. It took me a while to figure out what I had. It was not documented anywhere.....Only a few senior t-men even knew what I was dealing with....Schneider had never heard of it and was unwilling to supply Equiptment for this installation. I bought a new 240 volt Schneider Square D well pump controller and hacked it for this pump. It worked fine but distributor would not sell me the Equiptment to use on that job. I told them this one was for a different job. PG&E 's workers looked the other way. I had a faux artist paint the new Equiptment old to fool the supervisors......they did not notice the "painted rust".......LOL...painted dents and all...I got to did out my photos of this one......sometimes that is the only way to get things done here in the land of over regulation.  Government regulators need to be treated like mushrooms...feed them $hit and keep them in the dark....

Tecnodave

An issue that must be addressed with such an installation is that a 480/277 volt installation is not residential utility service so the residential rules for solar do not apply here, it's a totally different ball game for commercial solar, different rules all together.......check with your local power company and the local building authority before planning too far on this.  It may not even be allowed....
david