Cost of grid tie incidentals?

Volvo FarmerVolvo Farmer Solar Expert Posts: 209 ✭✭✭✭✭
After adding to my off grid system recently and realizing that Chinese solar panels are approaching $1/watt, I have been considering grid tying a commercial property I own.

It appears that I can get 5KW of panels and an appropriately sized inverter for in the $10K range. Assuming I don't need to buy racks, can anyone make a guess as to what the incidentals (wire, breakers, combiner boxes, etc) would run for a 5KW system? This would be no batteries, simple grid tie.

Two more things :-)

If I am in the 6 sun-hour annual insolation window according to NREL, would it be safe to use that figure in calculating output of a grid-tie system? Since I'm off grid, a lot of my generating capacity goes unused and I don't have accurate measurements.

Lastly, is there a thread on here comparing and contrasting enphase inverters with traditional single inverter systems?

Thanks!

Comments

  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: Cost of grid tie incidentals?

    If I am in the 6 sun-hour annual insolation window according to NREL, would it be safe to use that figure in calculating output of a grid-tie system? Since I'm off grid, a lot of my generating capacity goes unused and I don't have accurate measurements.

    For estimating system output you can use PVWatts (http://rredc.nrel.gov/solar/calculators/PVWATTS/version1/). It's really simple to use; you pick a location near you from the map, enter your system size (STC DC rating) along with the array tilt and azimuth. There is a lumped system derate that defaults to 0.77, which is a little pessimistic (I usually change it to 0.80 or 0.81), and hit "calculate". It reports a monthly kWh output projection that is fairly accurate. You can even get it to load an Excel spreadsheet with a year's worth of hourly data if you are a data nerd. ;^)
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Cost of grid tie incidentals?
    Since I'm off grid, a lot of my generating capacity goes unused and I don't have accurate measurements.

    Lastly, is there a thread on here comparing and contrasting enphase inverters with traditional single inverter systems?

    Thanks!

    Just to make sure we're all on the same page; if you are off-grid you will not be using Enphase inverters as they are grid-tie only.
  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: Cost of grid tie incidentals?
    Just to make sure we're all on the same page; if you are off-grid you will not be using Enphase inverters as they are grid-tie only.
    He is talking about a grid tied system.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Cost of grid tie incidentals?
    ggunn wrote: »
    He is talking about a grid tied system.

    I am confused about his statement "Since I'm off grid ..." which does not fit with the rest of the post.
  • jeffkrusejeffkruse Solar Expert Posts: 205 ✭✭✭
    Re: Cost of grid tie incidentals?

    It appears he has an off-grid system but he might have the grid avalible. I started that way.
  • solar_davesolar_dave Solar Expert Posts: 2,385 ✭✭✭✭
    Re: Cost of grid tie incidentals?
    I am confused about his statement "Since I'm off grid ..." which does not fit with the rest of the post.

    He is setting up a grid tie on another property.
  • solar_davesolar_dave Solar Expert Posts: 2,385 ✭✭✭✭
    Re: Cost of grid tie incidentals?

    Enphase inverters are great if you have any shading issues, different panel locations & directions, etc. The claimed warranties are great, just not really proven over time. They are pretty close to full inverter cost parity. They get rid of the need for high voltage DC runs to the main inverter as everything is handled as AC from the panel.

    The downside might be if they start to fail over time you will be pulling up the panels to switch them out one at a time.
  • Volvo FarmerVolvo Farmer Solar Expert Posts: 209 ✭✭✭✭✭
    Re: Cost of grid tie incidentals?
    solar_dave wrote: »
    He is setting up a grid tie on another property.

    This is correct. I am familiar with this stuff because I live off grid. I want to set up another grid tied system on another property.



    Thanks for the help so far. It seems that if I could self install a system for about $3/watt, the payback might be in the seven year range by the time I cash in on the incentives. Guess I need to sit down and make a shopping list and add it all up.
  • BB.BB. Super Moderators, Administrators Posts: 32,314 admin
    Re: Cost of grid tie incidentals?

    Our host, NAWS, does have some sample quotes you can look at (I don't know how often the pricing is updated).
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: Cost of grid tie incidentals?
    This is correct. I am familiar with this stuff because I live off grid. I want to set up another grid tied system on another property.



    Thanks for the help so far. It seems that if I could self install a system for about $3/watt, the payback might be in the seven year range by the time I cash in on the incentives. Guess I need to sit down and make a shopping list and add it all up.
    Make sure you read the fine print on the incentives. Some AHJ's require that the system be installed by licensed contractors (and some say that they must have NABCEP cert'ed PV installers on staff) in order to qualify for locally administered rebates. You will at least need a licensed electrician to install the interconnect hardware.
  • chevensteinchevenstein Solar Expert Posts: 100 ✭✭
    Re: Cost of grid tie incidentals?
    ggunn wrote: »
    Make sure you read the fine print on the incentives. Some AHJ's require that the system be installed by licensed contractors (and some say that they must have NABCEP cert'ed PV installers on staff) in order to qualify for locally administered rebates. You will at least need a licensed electrician to install the interconnect hardware.

    Not to split hairs, but you will find that there are some jurisdictions where there is no such thing as a licensed electrician. I was surprised by this when I came to NY: the more populous urban regions issue the licenses locally, but the more rural areas do not (electrical work is inspected, regardless of who did it, but there is often no requirement as to who does the work).

    That said, the utility itself may have requirements about who connects to their equipment, but then again they may not as they would have to administer their own qualification program in the absence of state licensure.
  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: Cost of grid tie incidentals?
    Not to split hairs, but you will find that there are some jurisdictions where there is no such thing as a licensed electrician. I was surprised by this when I came to NY: the more populous urban regions issue the licenses locally, but the more rural areas do not (electrical work is inspected, regardless of who did it, but there is often no requirement as to who does the work).

    That said, the utility itself may have requirements about who connects to their equipment, but then again they may not as they would have to administer their own qualification program in the absence of state licensure.
    That surprises me as well, but I did say that some AHJ's have licensing requirements for installers. For example, here in Austin you cannot qualify for the local rebate unless your system is installed by a city registered contractor with at least one NABCEP certified installer and a licensed master electrician on staff, and the master must perform the interconnect.
  • mikeomikeo Solar Expert Posts: 386 ✭✭✭
    Re: Cost of grid tie incidentals?
    but I did say that some AHJ's have licensing requirements for installers.
    I'm from Arkansas, what the heck is an AHJ, is there a shot available to prevent this condition?
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Cost of grid tie incidentals?
    mikeo wrote: »
    I'm from Arkansas, what the heck is an AHJ, is there a shot available to prevent this condition?

    AHJ: Authority Having Jurisdiction.

    Polite way of saying "trumped-up know-it-all bureaucrat with delusions of supreme power over all they survey". :p

    That was a JOKE, people. Some of them are actually human beings. I just keep running into the ones who aren't. :roll:
  • mikeomikeo Solar Expert Posts: 386 ✭✭✭
    Re: Cost of grid tie incidentals?
    AHJ: Authority Having Jurisdiction.
    Ok I see, here it would be our power provider, Entergy. They won't hook up a house unless there is at least 100 amp service, a meter loop, lockable disconnect and a ground rod. For grid tie, they require a solar cutoff switch at the meter loop and UL approved grid tie inverter. They do the inspecting before hookup. They could care less what happens to you beyond their meters, that is where their liability stops. This limits grid tie to an existing distribution panel so I wonder if a dual lug can be placed on the house side of the 200 amp lockable utility breaker below the meter, one for the inverter the other for the house load.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Cost of grid tie incidentals?

    :confused: No building/electrical code inspectors?
    Seems a bit odd that no one would care whether or not you were using proper wire/breakers/boxes/install/et cetera in your home.

    Sounds like you could get away with just about anything. That's not good. As much as we sometimes rant about the endless and complex code rules, most of them are there with good reason.
  • mikeomikeo Solar Expert Posts: 386 ✭✭✭
    Re: Cost of grid tie incidentals?

    N
    o building/electrical code inspectors?
    In spite of that, I don't think we have any more electrical related fires than other places. When you go to the local building supply, the only things that you can buy are UL rated product that are pretty standard, 200 amp panels, 20 amp breakers, 12/2 with ground romex, etc. It's not really rocket science, and any one who has the talent to design and build there on homes out of local materials probably will do OK. We have some of the most unique homes I have ever seen built from local trees and stone.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Cost of grid tie incidentals?

    I'm just a bit jaded due to the number of installs I've seen done by (presumably) "licensed" electricians that were wrong. They too used UL approved equipment, but if it's not connected right it's still dangerous.

    No, it isn't rocket science. But they still manage to make a pig's ear out of it sometimes. :roll:
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