Request recommendations on off-grid upgrade for refrig

cdre
cdre Solar Expert Posts: 78 ✭✭
in Off Grid Solar & Battery Systems #1
My LP refrig flaked out out on me, so I'm thinking of upgrading my current off-grid system to accommodate a small AC refrigerator. Looking for inputs on how best to accomplish this.

Current system: 3 110w panels at 12v, 4 6v Costco batteries (450ah @12v new - 4 years of light use), Blue Sky 25a charge controller, Harbor Freight 1500w inverter, Progressive Dynamics 80a charger, Trimetric 2025 meter. In Belize, Central America.

I have this set up on a 40' 5th wheel RV off-grid. It's essentially my vacation home seeing heavy use (lights, fans, ect) only 3 to 5 wks/yr. When I'm not there the only load is infrequent use of the TV. My dad previously used the original LP refrigerator full-time (his trailer on the property has an older, much less efficient LP refrig).

Considering adding a small, efficient refrigerator rated at 300 kWh/yr. I'm assuming in a non climate controlled environment, I'll see around 30% more energy use than rated.

I know I won't have a ton of extra capacity beyond powering the refrigerator, but with such infrequent loads over that, I'm fine with running the generator when required.

I don't want to upgrade to a 24v system (everything in the trailer is 12v and all supporting equip is 12v). I do expect this system to see use for another 10 years or so.

I'm thinking of adding around three 140w panels (420w) and an appropriate controller. Not sure of how to rig this up, though. Can I put these on another Blue Sky controller and wire it in parallel the the existing charger?

Batteries aren't exactly fresh... likely I'll need to buy another set?

Here are my calcs:
Attachment not found.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
    Re: Request recommendations on off-grid upgrade for refrig

    Without going to 24 Volt ...

    The biggest shortcoming you have is the HF inverter; it is most likely MSW type and therefor no good for motors. Try and get something like a ProSine 2000 or Samlex/Cotek SA 2000 http://www.solar-electric.com/sa2wa12vosiw.html

    The 450 Amp hours of batteries will probably work: I have roughly the equivalent amount of power in my system. But your paneling is a tad shy at 330 Watts. For that much battery you'd be better off with 700 or more Watts. Check the batteries with a hydrometer and see how fully charged they are and how consistent the SG is across all cells.

    You can parallel charge controllers, but it might be time to bite the bullet and ditch the Blue Sky for a good MPPT unit that can handle the full load. The question would be what the actual specs on the existing panels are. I would guess Vmp 17.5 & Imp around 6. This could make mixing with different panels all on the same controller problematic since there are only three of the small panels.

    My 16 cu. ft. 'frige uses about 1.2 kW hours per day. There are some now that can do better. Do not expect a smaller unit to automatically equate to less energy consumption.
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #3
    Re: Request recommendations on off-grid upgrade for refrig

    What shooed to the LP fridge? just curios.

    Cooling units are pretty easy to replace (albeit they can be expensive) other items, Ike Control board, igniters, etc are pretty cheap.

    Tony
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  • cdre
    cdre Solar Expert Posts: 78 ✭✭
    #4
    Re: Request recommendations on off-grid upgrade for refrig

    I'm currently at 330w on one Blue Sky... thinking of adding 420w (3 of these) on another Blue Sky controller. Looking into it more, there is a function where they can network together, so that might be doable. That would get me to 750w.

    Not sure what caused the LP fridge to fail. Flame looked great - assumed the controller was ok. I powered the electric off a generator, confirmed high temps where the gas should heat the system and saw no changes to the temps internally... (using remote temp gauge). Guessing it had a leak in it somewhere, letting the magic out. I can spend money to get it fixed, but since I run it full time, I figured I should consider going electrical.
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  • cdre
    cdre Solar Expert Posts: 78 ✭✭
    #5
    Re: Request recommendations on off-grid upgrade for refrig

    Thanks for the input on the inverter. I did a little research and it looks like the modified wave inverter will be about 20% less efficient to run than a true sine wave. Any reason a Xantrex Prowatt SW2000 wouldn't be a reasonable option? Can be had for around $400.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #6
    Re: Request recommendations on off-grid upgrade for refrig
    cdre wrote: »
    Thanks for the input on the inverter. I did a little research and it looks like the modified wave inverter will be about 20% less efficient to run than a true sine wave. Any reason a Xantrex Prowatt SW2000 wouldn't be a reasonable option? Can be had for around $400.

    Technically that one is designed for mobile applications, but that's nit-picking. It's six of one, half-dozen of the other: you want to get around 2kW of pure sine inverter. Beware of GFCI outlets on any inverter; you'll probably have to remove them (they seem to be problematic across the board). Being able to hard-wire the output eliminates this and other issues.

    FYI, I ran the 'frige off MSW to begin with; it clattered on start-up, drew more power, and I wasn't happy with the result. Replaced the inverter; no more problems. With anything. :D
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  • cdre
    cdre Solar Expert Posts: 78 ✭✭
    #7
    Re: Request recommendations on off-grid upgrade for refrig

    Any thoughts on this as a refrigerator option? GE 18.1 cu ft

    Any recommendations?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,646 admin
    #8
    Re: Request recommendations on off-grid upgrade for refrig

    That was similar to the GE fridge I purchased a couple years ago (GE GTH18EBC2RWW, no longer available at 311 kWH per year energy star tag)... Seems to work very well for us.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #9
    Re: Request recommendations on off-grid upgrade for refrig

    Ask the supplier which models are made by which manufacturer. I did at Sears and was quite surprised... there really are only 3 makers left in NA if I remember...
     
    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
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  • cdre
    cdre Solar Expert Posts: 78 ✭✭
    #10
    Re: Request recommendations on off-grid upgrade for refrig

    A quick update on my plan... Shipping everything to Belize through Miami and found a local solar retailer who can deliver to a freight forwarder. Panels are very reasonably priced...

    Downsizing to a 10 cu ft Vissani refrig (HMDR1030WE) - should fit where the Dometic is coming out with limited modifications and is rated at 312kWh/yr.
    Adding 4 130W 12v panels (17.3 Vmp, 7.52 Imp)
    BlueSky SB3024iL charge controller (paralleled with my pre-existing 2512iX)
    Xantrex PROwatt SW 2000
    and 4 fresh T-105's

    I'll combine that with my pre-existing 330watts of panels and 80amp Progressive Dynamics converter.

    Cost for everything landed in Belize should be around $2,300. Breakeven on pre-existing butane costs will be in about 40 months.

    Not too shabby...
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