shop power

System
System Posts: 2,511 admin
in Solar Beginners Corner #1
New to solar and just joined the forum. I am building a shop and want to go all solar. Seven grand just to bring the power up to the building and I get to dig the trench, I get to run the conduit and I get to pay electric bills for the rest of my life convinced me to go all solar with generator back up.

So I will build the shop first and then the house. Right now I am planning two seperate systems unless anyone has some other ideas. I don't think the house will get started for a couple of years.

I live in Sierra Vista AZ and we get lots of sun (6.5 hrs a day avg). I figure the shop will use an average of 5000 watt hrs/day. I don't want any DC loads, so all AC through a 100 amp service. I plan on using some 220V equipment including an A/C, welder and car lift. I figure using only one 220V piece of equipment at a time. Basically turn off the A/C when using the other stuff.

Right now I am figuring on 6 - 200W modules for 1200W total. I also figure on 8 - Rolls S600 batteries ( 6V and 450AH ) in a stright string for a 48V system.

Is this a good plan? What inverter and charger would you (guru's) recommend?
I also have a 7000W generator I could use when needed. How would that tie into the system? Thanks. Mike
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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #2
    Re: shop power

    HI, there is a string here somewhere, I forget the Original Posters name and he designed an entire machine shop and runs it off solar. It is in Hawaii and on or near a military base. Your answer may be there ... maybe Bill B will remember.
    hth
    ej
     
    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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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #3
    Re: shop power

    Welcome to the forum.

    Could you be convinced to run the heavy power stuff off the gen as needed? No? Okay.

    Gets a bit tricky, as you can't run 240 VAC through a Kill-A-Watt. Thus were left with power usage estimates, which can be the downfall.

    5000 Watt hours per day isn't too difficult. Seems to me I was just answering almost identical questions for someone else! Must be something in the air today. :D

    The 450 Amp hours @ 48 Volts is a good number. At 25% DOD you'd be around your 5 kW hour figure.
    I think you may want to increase your array size, as the peak charge current from 1200 Watts on a 48 Volt system will be a bit low for that battery bank size. Even though it should supply the necessary Watt hours, you want to get the batteries recharged quickly. Normally I'd suggest about 3 kW of panel for that bank. In your area the panels are bound to run hot, which drops output considerably.

    Do you have a number for maximum Watts all at once? I think you might want to be looking at the Xantrex XW 6048 here; plenty of capacity to spare (surge to 12 kW).
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  • Vic
    Vic Solar Expert Posts: 3,208 ✭✭✭✭
    #4
    Re: shop power

    Hi mjmulia,

    I would not ever run a welder on my inverters, seems risky. Do run one on a generator, tho. Just a personal preference.

    Sounds like you will have a fun couple of years. Good Luck, Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
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  • Ralph Day
    Ralph Day Solar Expert Posts: 1,023 ✭✭✭✭
    #5
    Re: shop power

    If it were me I'd bite the bullet and have utility power installed and net meter (if possible) instead of trying to off-grid everything. My shop has some power from my off-grid setup, and some from the utility. The performance of power tools is so much better on the grid (could be to do with the 140 foot distance from inverter to shop).

    I went 6 years totally off grid and just stopped using some of the tools in the shop because of excessive power consumption. Now their consumption is negligable on the utility bill. We can monitor the daily use and such, even down to how many kwhrs and cents it cost for a certain day's work in the shop...11 cents for last weekend's wood working. Utility power is now at the shop and the house is backserviced from there (see links in signature). Works fine for me, not sure about the next owner (daughter after they take me out feet first):p

    Ralph
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,642 admin
    #6
    Re: shop power

    "adas" built a solar powered fabrication business in Hawaii... Did it on the low cost side using used forklift batteries and large/inexpensive/EBay MSW inverters...

    Look for threads started by Adas.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • System2
    System2 Posts: 6,290 admin
    #7
    Re: shop power

    Thanks guys for the responses. I would like to grid tie but the shop is even further away than the future house. It will cost me 10 grand to bring power to the shop!

    It is relatively cheap to add more panels so I think I will do that. I will look into the bigger inverter. I talked to a guy at Real Goods and he advised me that the Magnum MS4448 PAE inverter/charger would be the way to go. I already have a welder that runs on 110V and for bigger jobs I could just go oxy/aceteline.

    Any further thoughts? Mike
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  • System2
    System2 Posts: 6,290 admin
    #8
    Re: shop power

    Can you explain your message about not being able to run 240VAC through a kill-o-watt? Mike
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #9
    Re: shop power

    It could cost you more than $10,000 to run it from PV.

    I think you'd be happier with the XW than the magnum. Shop tools, right? Drill press, lathe, cut saw, things of that nature? All with fairly hefty AC induction motors that have very high surge demands. 4 kW could be marginal power, depending on what you run and how much other stuff is on at the same time. Air conditioning, particularly in that climate, can be a big power consumer. You really do need some load numbers before proceeding, otherwise you'll just be guessing at equipment and may either come up short on power or spend too much money.

    One other thing I'll mention: the plans include a future house, right? If you use the Xantrex unit, they are "stackable" and you could add another inverter/battery bank/array and join them together; share the power between the two installs. That is more efficient than two separate systems, especially when you need to supply occasional high-power loads like compressors - either air or refrigeration.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #10
    Re: shop power
    mjmulia wrote: »
    Can you explain your message about not being able to run 240VAC through a kill-o-watt? Mike

    Simple: K-A-W meters are 120 VAC plug-in devices. If anyone knows of a 240 VAC version, please speak up! That would be a godsend for many of us.
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  • System2
    System2 Posts: 6,290 admin
    #11
    Re: shop power

    To Cariboocoot, My max usage would be about 7600 watts. That would be with the A/C on, half the lights, a small fridge and runing a piece of equipment that consumes 10 amps.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #12
    Re: shop power
    mjmulia wrote: »
    To Cariboocoot, My max usage would be about 7600 watts. That would be with the A/C on, half the lights, a small fridge and runing a piece of equipment that consumes 10 amps.

    That would overwhelm the 6kW Xantrex, never mind a 4kW Magnum.
    So you either cut back on power use, or double up on inverters for those high-power times.
    See what I mean about it getting expensive fast? You've "just spent" half of that $10k on inverters; no batteries, no panels, no charge controller, no miscellaneous hardware.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,642 admin
    #13
    Re: shop power

    As a point of reference--And XW6048 (6kW 48 volt) hybrid inverter will supply ~12kW surge--and for such surge, you will need a minimum of 600 AH of 48 volt battery bank for you to be happy.

    Solar PV power is not cheap... Work out the 20 year cost of solar (up front capital costs, battery replacement every 8-15 years or so, new inverter+charge controllers every 10+ year, the fact you cannot use 100% of the power collected every day--try 75% of collected power, cost of backup genset to install/fuel--if you have one, etc.)...

    My bet is that you will be looking at $1-$2+ per kWH.. If you are using a lot of power, that $10,000 cost only works out to $42 per month over 20 years +$0.10-$0.20 per kWH used.

    -Bill "why yes, this is a solar forum" B. ;)
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #14
    Re: shop power

    While we're doing "theoretical costing":

    600 Amp hour 48 Volt battery bank: $4,800 (16 325 Amp hour Crown 6 Volt)
    3500 Watt array to recharge same (based on $2.50 per Watt): $8,750
    Two Xantrex XW 4548 inverters: $6,000

    Major component total: $19,550

    How's that $10k to install grid power looking now?

    Yes, this is a solar/RE forum. But we're also realists. Rule #1 of off-grid power is to reduce consumption as much as possible. Building a system capable of powering heavy loads is expensive, and impractical if those loads are not in steady use; most of the time a large portion of the capacity you've paid for sits idle. That's not a good return on investment.

    What was the first question I asked? "Could you be convinced to run the heavy power stuff off the gen as needed?" Now you know why I asked.

    I'm not saying it can't be done or shouldn't be done. But we all here want you to realize what's involved before you take the plunge. You may be able to compromise on some loading, find some bargains (don't even think about cheap MSW inverters for running AC motors), get used forklift batteries, rely on the gen for bulk charging to defray panel costs. But you have to know what you're up against.

    Remember: it's your money you're spending, not mine. :p
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