AC load center for off-grid inverter

I'm trying to narrow down my options for an AC "load center" for our off-grid house. Here are the specifics:

1) We will be completely off-grid (no grid tie whatsoever).
2) I've got a Magnum MS-4448PAE (120v/240v) Inverter and a Mini Magnum Panel (MMP) that are already pre-wired together. The MS-4448PAE can output 30amps on two separate legs (Hot 1 and Hot 2).
3) I will have 7 separate 120v AC circuits (vary from 15amp to 20amp) all using home-run wiring (no shared neutrals) serving our off-grid house. I do not have any 240v AC circuits right now, but might in a year or two.
4) It would be nice if the load center was designed for outdoor use (i.e. NEMA 3-R), even though the area where the Inverter/CC/MMP/Load center are to be located is covered and out of the rain.
5) I will have a small gas generator connected to the AC In of the MMP on occasion to charge the batteries, but this will not be involved with the AC load center I am asking about. However, it's still important to consider.

Given these specifics, what sort of AC "load center" should I be looking at? I don't want a monster 200amp load center, but I also would like room to add another 1-2 circuits (120v or 240v) in the future.

Any suggestions? Availability of breakers, etc. is important, so I'd like to stay with a readily available brand (Square D, GE, C/H, etc.) that are available at most box stores.
100% Off-grid with: 8 Solarworld 275 Watt Panels, 8 Concorde SunXtender 405aH 6v AGM Batteries, MS-4448PAE 48v Inverter, MidNite Solar Classic 200 Charge Controller, 10,000 gallon rainwater collection system, etc.

Comments

  • BB.BB. Super Moderators, Administrators Posts: 30,625 admin
    Re: AC load center for off-grid inverter

    Any chance that there will be grid power in your life time? A full panel replacement (using an electrician) seems to run well north of $2,000 -- Paying a couple hundred bucks for a larger box to avoid the cost of adding utility power (and all the appliances/HVAC/etc. that implies), may well be worth the added costs now.

    And if not pulling, at least installing empty conduit to logical points in the house (HVAC pad, shop power, etc.)--Having places you can run wire and not having to rip up sheet rock, concrete drive/walkways, etc. may be appreciated a decade or so later.

    Also--I would plan on a pair of generator and battery shacks. Keep the genset+fuel separate from the rest of the structures (batteries, solar panels, home, etc.). Limit your losses if there is a fire somewhere (generator, battery+electronics).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • pechanpechan Solar Expert Posts: 92 ✭✭
    Re: AC load center for off-grid inverter

    I would buy something similar to this for your application http://www.lowes.com/pd_13088-296-HOM20L125RB_1z10w6g+1z10wgf+1z11wsu+4294722482__?productId=1131719&Ns=p_product_qty_sales_dollar|1&pl=1&currentURL=%3FNs%3Dp_product_qty_sales_dollar|1%26page%3D1&facetInfo=Main%20lug|20.0|Outdoor Surface Mount it and back feed it with a 2 pole breaker from your inverter. If you ever need more circuits you can add a subpanel next to it without doing too much work.
  • BB.BB. Super Moderators, Administrators Posts: 30,625 admin
    Re: AC load center for off-grid inverter

    Note that a few people had to even put in Meter Sockets for their off grid installation--Local code required a meter socket even if the system was off grid (caused a little consternation at times when the building had power, however no meter--Illegal "grow" operation?).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • westbranchwestbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Re: AC load center for off-grid inverter

    Check with a local electrical installer and find out which Square D QO distribution boxes he uses the most of and see if the price is lower than the smaller ones, bulk buy prices come into play..

    Locally a 100A service with main breaker is cheaper than just the breaker, same issue for the 150 A and 200A boxes, although at a higher price. Also the 100A 24 box is half the price of a 12 slot box 100A
    ???

    Smaller is not necessarily cheaper...
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • Hill_CountryHill_Country Solar Expert Posts: 96 ✭✭
    Re: AC load center for off-grid inverter

    I can see the "smaller isn't necessarily cheaper" thing for sure. In that case, if I went with a 100 amp breaker in a 100 amp Load Center...the 100 amp breaker will not do anything (safety-wise at least) for me because the inverter is only pushing out a max of 30 amps per leg. The only gain (besides being readily available and cheaper) is that, in the future, I could add grid tie (with a meter) and I wouldn't have to completely redo the AC load center. Is this correct?
    100% Off-grid with: 8 Solarworld 275 Watt Panels, 8 Concorde SunXtender 405aH 6v AGM Batteries, MS-4448PAE 48v Inverter, MidNite Solar Classic 200 Charge Controller, 10,000 gallon rainwater collection system, etc.
  • BB.BB. Super Moderators, Administrators Posts: 30,625 admin
    Re: AC load center for off-grid inverter

    Yep... Don't know about your area--But some building departments have a minimum panel size (something between 125 and 200 amps). You might want to double check what the code requires in your area/house size/etc.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Mountain DonMountain Don Solar Expert Posts: 494 ✭✭✭
    Re: AC load center for off-grid inverter

    If you use a typical residential panel made for 240 VAC you may need to only use one side of the panel if you only have a 120 VAC supply. Or you can wire a jumper to light up both sides of the breakers. Minor rewiring if and when you either do 240 with stacked inverters or a grid tie. Unless you buy one of those magnum 120/240 inverters to start with.

    The panel may not come with the main (100amp) breaker. Mine never did.
    Northern NM, 624 watts PV, The Kid CC, GC-2 batteries @ 24 VDC, Outback VFX3524M
  • westbranchwestbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Re: AC load center for off-grid inverter

    Yup, I have a 1500W inverter ( ~14A) going into a 100A service breaker.

    However what about an upgrade to the backup gen set? My Honda is a 3000W and the surge is higher... some here have upwards of 12 Kw gensets...
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • PhotowhitPhotowhit Solar Expert Posts: 5,203 ✭✭✭✭
    Re: AC load center for off-grid inverter

    I think something that hasn't been mentioned is that some load centers come with neutral/ground bonded. Often if you have the inverter 'upstream' you will have a breaker and bond there, closer to the ground, in essence making what in most homes would be the main panel a sub panel. You typically want the bond closes to the ground, so you would want to disconnect this bond.

    Not sure what your plans are, but since you have the 120/240 option, I would wire the panel so you could use the 240. No reason not to...

    I intend to have a 240 volt option in the future, but have been 'stuck' with a 120v inverter and just wired into the 200 amp former main, and jumped the 2 hot connections and pulled the wires from the existing 240 breakers, other than the hot water which Is running at 120v. It's ugly with a bunch of capped and or taped wires, but safe.

    Always nice to have an electrician look over your shoulder!
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, 660 ah 24v ForkLift battery. Off grid for @16 of last 17 years. Assorted other systems, and to many panels in the closet to not do more...lol
  • Hill_CountryHill_Country Solar Expert Posts: 96 ✭✭
    Re: AC load center for off-grid inverter

    Thank you all. Given that I'm off-grid and my inverter (a Magnum MS-4448PAE - 120v/240v output) can output 30amps on two legs (Hot 1, Hot 2) and handle 240v, I will just go ahead and get a standard 100amp/125amp main breaker load center (i.e. the kind that are intended for a traditional grid-tie install that you can get at about any big box store) and use this 100amp/125amp main breaker load center as a "sub-panel", rather than a main panel, like what photowit suggests. I will wire it as 240 volts (Hot 1 to one leg, Hot 2 to the other leg) and make sure that I balance the breakers for even load distribution on the two legs (mostly 120volt loads, but may have a 240 load in the future). I will be sure to make sure that the neutral-ground bond is at ONE place only in the system (i.e. most likely in the Magnum Mini Panel (MMP)) and not two places (big no-no).

    Does anyone have any specific recommendations in terms of brands (Square D QO, Homeline, CH, Siemens, GE, etc.)? I've been looking at the Square D QO line for my main subpanel, only because I've seen them for sale just about everywhere.

    Since I have a 48v system on the DC side of things, I already have a separate box and MidNite Solar DC breakers that will handle our off-grid DC circuits in the house (pump, ceiling fans, and fridge + freezer). After the AC and DC output wires leave the MMP, both these systems (AC and DC) are completely separate (separate conduit, separate boxes, etc.).

    Thanks!
    100% Off-grid with: 8 Solarworld 275 Watt Panels, 8 Concorde SunXtender 405aH 6v AGM Batteries, MS-4448PAE 48v Inverter, MidNite Solar Classic 200 Charge Controller, 10,000 gallon rainwater collection system, etc.
  • Mountain DonMountain Don Solar Expert Posts: 494 ✭✭✭
    Re: AC load center for off-grid inverter

    I like SQ D QO myself. A side benefit is they can be used on low voltage DC as well as AC. Limit of 48 volts absolute, so okay on 24 volt battery but not 48. The AIR is only 5K so a good DC fuse between the breakers and the battery is a good idea.
    Northern NM, 624 watts PV, The Kid CC, GC-2 batteries @ 24 VDC, Outback VFX3524M
  • ramlouiramloui Solar Expert Posts: 103 ✭✭
    Re: AC load center for off-grid inverter

    Hello Hill_Country!
    I have the same set-up as you except it is the 24V Magnum. My system is installed in the shed. So what I did is wire the inverter AC output to a small distribution panel right next to it so I could power a light a a few outlets in the shed (2 x 15A breakers) (see picture). In that same panel, I then installed a 30A 240V breaker that feed a second distribution panel in the cabin. That one is also not large as it contains 8 circuit breakers. At this time I do not have 240V loads. When I do, I will have to install a bigger panel to accomodate a few more circuits. I use Squade D QO breakers because of their availability.
    Attachment not found.
    Cheers!
    Off-grid cabin in northern Quebec: 6 x 250 W Conergy panels, FM80, 4 x 6V CR430 in series (24V nominal), Magnum MS4024-PAE
  • BB.BB. Super Moderators, Administrators Posts: 30,625 admin
    Re: AC load center for off-grid inverter

    If you ever have a chance to install utility power--You might want to make this a "protected" sub panel... I.e., all the loads you want to drive with solar/genset power--And an area for "main panel" for utility power (air conditioner, water heater, and other large loads). The power from the main panel would go to your AC inverter/transfer switch, then to the "protected" sub panel.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • pechanpechan Solar Expert Posts: 92 ✭✭
    Re: AC load center for off-grid inverter

    Just a FYI
    Siemens and GE breakers are interchangeable.
  • jaggedbenjaggedben Solar Expert Posts: 230 ✭✭
    Re: AC load center for off-grid inverter
    ... I will just go ahead and get a standard 100amp/125amp main breaker load center ...

    You really can't go wrong with this. Just get whatever's cheapest (including the cost of the breakers you need) at the handiest supplier. UL standards for load centers have come quite a ways in the last few decades and the brand really, really doesn't matter much.

    You can also use some panels that don't have a separate space for the main breaker (main-lug-only or MLO panel). You just put a hold-down device on the breaker you use to connect the inverter, as that becomes the main.
  • Alaska ManAlaska Man Solar Expert Posts: 252 ✭✭
    Re: AC load center for off-grid inverter

    You don't have to use a 100Amp breaker for the main. I have a Square D box and ran my power into a 30Amp breaker, so It's acutally going to do what it is supposed to do............. protect my crap.
  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: AC load center for off-grid inverter
    Alaska Man wrote: »
    You don't have to use a 100Amp breaker for the main. I have a Square D box and ran my power into a 30Amp breaker, so It's acutally going to do what it is supposed to do............. protect my crap.
    But in some cases (package deals from big box stores) it is cheaper to get a panel with a main breaker and just ignore or remove it and use a 30A breaker included in the package to serve the function of the main.
    SMA SB 3000, old BP panels.
  • Hill_CountryHill_Country Solar Expert Posts: 96 ✭✭
    Re: AC load center for off-grid inverter

    Thank you all! This forum is a great resource!

    I will be using an appropriately sized main breaker load center from a major manufacturer (Square D, GE, Siemens, etc.) and will simply get a double pole, 30 amp breaker as my "main breaker". The reason for the 30 amp double-pole main breaker (vs. a double pole 100 amp/125amp/200amp breaker) is because I will be using a Magnum MS-4448PAE 120v/240v inverter, which is capable of producing 30amps at 120v on each leg.

    With the exception of the neutral/ground bond, in terms of wiring I will just treat the load center as if it is connected to the grid, even though I'm completely off-grid! That way, if I ever do a grid-tie only setup, it will simply involve changing out the main breaker to a more appropriate size and then re-establishing the neutral/ground bond. Currently the pre-wired power center I have (MPP with Magnum Inverter and Classic 200 charge controller) will contain the neutral/ground bond for the system. I am also not doing any multi-wire branch circuits, even though I can with the inverter I have.
    100% Off-grid with: 8 Solarworld 275 Watt Panels, 8 Concorde SunXtender 405aH 6v AGM Batteries, MS-4448PAE 48v Inverter, MidNite Solar Classic 200 Charge Controller, 10,000 gallon rainwater collection system, etc.
  • Hill_CountryHill_Country Solar Expert Posts: 96 ✭✭
    For those that are interested, I wanted to post an update on our AC load center at our off-grid place. I ended up using a GE PowerMark Gold 125amp Outdoor main-lug load center that I purchased for about $40 from a home improvement chain store and it has been working great for our needs. I then used a GE 30amp double pole breaker and backfed it from the L1/L2 output of our Magnum MS-4448 PAE inverter (48v). The Magnum Inverter is limited to 30 amps on each leg, so using a 30amp double pole breaker allows me to still be able to use it as a main breaker, but it also actually protects the load center as well (instead of using a 125amp main breaker as the main breaker when the maxiumum output current of the Magnum is 30amps on each leg). I purchased the optional main breaker lock-down kit that secures the backfed 30amp double pole breaker, as per NEC requirements.
    100% Off-grid with: 8 Solarworld 275 Watt Panels, 8 Concorde SunXtender 405aH 6v AGM Batteries, MS-4448PAE 48v Inverter, MidNite Solar Classic 200 Charge Controller, 10,000 gallon rainwater collection system, etc.
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