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Thread: Solar power for the shop?

  1. #1
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    Default Solar power for the shop?

    I'm in the early planning stages for a bow shed shop.

    A major challenge is my electrical service. My 100 amp panel is tapped out, and upgrading to 200 amps with a subpanel to the shop would be $$$ -- back-of-the-envelope estimates from contractor friends are running $3k - $4k and possibly higher. The expense is painful enough, but worse is that when I sell the house, the increased capacity won't do much for the selling price.

    I'm in New Mexico, so sunlight is abundant and solar power is at least more feasible here than in some other parts of the country. Seems to me that while a solar system tied to the grid would also be expensive, it could come with me should I decide to sell the house. On the days when the shop isn't getting much use, it is defraying its cost (New Mexico has mandatory net metering for solar installations).

    Pros and cons? Where to look for enough info to start roughing out the system and putting some numbers together? For discussion purposes, the shop will have the usual assortment of stationary and portable power tools, some kind of dust collection system, basic lighting, a pellet stove, swamp cooler, etc. It will be my personal space, so it will be rare that multiple tools will be running at the same time. The shop will be roughly 18' x 40', give or take a bit.

    Thoughts?

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    Default Re: Solar power for the shop?

    There's plenty of web sites that'll help you size your components. A 5KW system will be about minimum to run two major tools, like a table saw and a dust collector. The basic components will be the solar panels, charge controller, battery bank, and inverter. It won't be cheap.

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    Default Re: Solar power for the shop?

    Quote Originally Posted by TerryLL View Post
    A 5KW system will be about minimum to run two major tools, like a table saw and a dust collector. The basic components will be the solar panels, charge controller, battery bank, and inverter. It won't be cheap.
    Definitely not cheap. We installed a 4 kw grid-tie system last year and it cost $27,000 (we got a grant and tax credits for $18,500, so it worked out nicely). If you do all the installation you might save $8-10k.

    If you're popping breakers on a 100-amp panel, you need more capacity and the solar option is not the best way to accomplish that. Batteries/inverters are not good at providing the sort of surging current demanded by large power tools.

    If you're hoping to generate the power needed for the tools, a grid-tie system will bank power when you're not running the tools, and you can draw from the grid when you need the power. To get better service from the panel, you might do some rewiring and put the most power-hungry tools on separate breakers, so you don't have several things running at once on the same breaker. It helps to do a wiring diagram with the loads mapped out for each breaker. (We have a 100-amp panel for the garage/shop and attached greenhouse, so I've dealt with this sort of circuit overload problem).

    For a solar workup, you need to have the electrical consumption for each tool and estimate the hours you run it per month. Then you calculate the lighting, heat, pumps, and other loads. That should give you a benchmark.
    Last edited by Chip-skiff; 05-06-2012 at 01:02 AM.

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    Default Re: Solar power for the shop?

    If by "tapped out" you mean that there is no room for any more breakers this may help.

    My carport and guest room are served by a 60A branch circuit. The little 60A panel is full, there is no space for any more breakers. If and when I want more capacity I can replace the standard size breakers with what are known as miniature or space saving breakers, thereby allowing twice the number of breakers in the panel. I know, that sounds like a potentially overloading situation, but it's not, since the branch circuit will still be protected by it's 60A breaker in the main panel.

    In your case you may be drawing a lot of amps from the main panel for the shop, and that combined with the household draw may cause your main breaker to open when, for instance, the water heater and the oven and the drier are all on at the same time. It may work for you to open the drier and water heater breakers, or whatever, when you will be working in the shop. If you forget the main will still protect the system.

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    Default Re: Solar power for the shop?

    How's the breeze in your area. I think that wind power is going to be much more cost efficient that PV power very soon, if not already.

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    Default Re: Solar power for the shop?

    Quote Originally Posted by Gib Etheridge View Post
    If by "tapped out" you mean that there is no room for any more breakers this may help.

    My carport and guest room are served by a 60A branch circuit. The little 60A panel is full, there is no space for any more breakers. If and when I want more capacity I can replace the standard size breakers with what are known as miniature or space saving breakers, thereby allowing twice the number of breakers in the panel. I know, that sounds like a potentially overloading situation, but it's not, since the branch circuit will still be protected by it's 60A breaker in the main panel.

    In your case you may be drawing a lot of amps from the main panel for the shop, and that combined with the household draw may cause your main breaker to open when, for instance, the water heater and the oven and the drier are all on at the same time. It may work for you to open the drier and water heater breakers, or whatever, when you will be working in the shop. If you forget the main will still protect the system.
    That is what I was thinking. How is one man using a hundred amps? are you popping or just outta room?

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    Default Re: Solar power for the shop?

    The good thing about 220 is that you can run on half of the amperage. Upgrade where you can, most motors over 1hp will go either way.
    Steve Martinsen

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    Default Re: Solar power for the shop?

    "Tapped out" means there is no more room in the main panel. It already has the "mini-breakers" (cheap tract home construction), so no help there. I pop the occasional breaker in the shop, but never the main. But there's no room for expansion for a subpanel to a shop building.

    The other option might be to check with the power company and see if the shop can get its own meter. Perhaps this would simplify things by not requiring upgrading of the main panel in the house?

    Assuming a proper design, I could install the solar system myself, leaving the grid tie-in to the pros.

    Grants for solar installations? Never heard of 'em. Will try Google, but if anyone has a lead, I'd love to hear about it.

    In the meantime, I'll visit the local library for a basic book on electrical system design. It probably makes more sense to have some sense of the total electrical requirements before running out to look at solar gear.
    Last edited by Desert Sailor; 05-06-2012 at 10:23 AM. Reason: grammar nazi

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    Default Re: Solar power for the shop?

    Perhaps this would work for you.

    Pull and disconnect one of the 220V breakers, say for the drier circuit.

    Install a subpanel between the main panel and the drier and protect it with a breaker where the drier breaker was.

    Reconnect the drier to the subpanel.

    Install a branch circuit to the shop on the subpanel.

    As long as your wires are sized properly and your breakers don't exceed the wire capacities this will work.

    Looks to me like you want to learn more about and play with solar. No harm in that of coarse, but it may be too expensive to be worth it. I'll butt out now.
    Last edited by Gib Etheridge; 05-06-2012 at 10:37 AM.

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    Default Re: Solar power for the shop?

    Quote Originally Posted by Gib Etheridge View Post
    Perhaps this would work for you.
    Pull and disconnect one of the 220A breakers, say for the drier circuit.
    Install a subpanel between the main panel and the drier and protect it with a breaker where the drier breaker was.
    Reconnect the drier to the subpanel.
    Install a branch circuit to the shop on the subpanel.
    As long as your wires are sized properly and your breakers don't exceed the wire capacities this will work.

    Looks to me like you want to learn more about and play with solar. No harm in that of coarse, but it may be too expensive to be worth it. I'll butt out now.
    Great minds think alike, sorta. I have two 220V circuits in the main panel; one for a dryer, and one for an electric range. We use a gas dryer and range/oven, both of which only require 120V, so I rededicated those circuits to the garage/shop for the bigger stationary equipment.

    But a shop outbuilding would likely require more than the 50 amps that these two circuits can handle -- I think.

    Yeah, playing with solar would be an interesting and possibly useful learning experience. But I'm more interested in getting enough power to my shop without an investment that is basically sunk, and which I'll never recover.

  11. #11
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    Default Re: Solar power for the shop?

    I don't see why you can't install a 100A breaker in one of those unused 220V positions and run the shop off of it. Run it by your electrician. Buy him a sixpack or two for having come in twice.

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    Default Re: Solar power for the shop?

    My shop space runs off of a 40 amp sub panel. So far I've restored one vintage truck, built 1.5 boats and done a lot of mainteneance on my motorcycles without any issues. This is a hobby shop, so with the exception of my 220v air compressor everything else is 110. Small MIG welder, 10" bandsaw etc. A one man operation just doesn't have to use all that much power, especially if as in the OP case of using a pellet stove for heat.

    Speaking of stoves, when I went in to get permits (Washington State) the authorities didn't like seeing a wood stove in a "shop" space, so I erased it.

    Steve

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    Default Re: Solar power for the shop?

    I took care of an off-grid home in AZ that had a wood shop in the garage, they used a propane backup generator, kicked on when the power dropped to a certain level. If you can build a sound-baffling room for one, a generator might be a solution. Diesel would be better, IMO, more bang for the buck, literally.

    If you want to try banking power and running off the bank, forklift batteries are a good value, but all this is getting up there in price. You'll still need an inverter and charge controller.

    BTW, I love NM, lived in the East Mountains for a while. Still miss motorcycling there.

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    Default Re: Solar power for the shop?

    I have a 3hp table saw,some outlets and some lights running on a 50A sub.
    What else does one guy need?
    R
    Sleep with one eye open.

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    Default Re: Solar power for the shop?

    Just a word about the economics of a diesel generator:

    I ran a 6 kw Northern Lights genset to power my shop in Alaska, back when diesel sold for 75 cents a gallon. Fuel economy for that unit is typically 2 hours per gallon when run at medium load, say 3 kw, resulting in a cost of 12.5 cents per kwh. Not bad.

    At $4.00 a gallon for diesel, the cost of power becomes 66 cents per kwh, about 6 times the cost of power off the grid. Add the amortized cost of the genset, plus regular maintenance and repair, and you'll be well over $1.00 per kwh for power you can buy off the grid for 1/10 that cost.

    And a 50 amp subpanel will provide up to 11 kw at about 10 cents per kwh, at an installation cost about equal to the cost of that genset.

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    Default Re: Solar power for the shop?

    The US Dept. of Energy has several programs that provide block grants to states for renewable energy incentives. In Wyoming the grants are administered by the Business Council. But if you search DOE - renewable energy grants - (your state), you should find some leads. Other sources are USDA rural renewable energy programs. If you use your shop for business, you might qualify for other grants (usually larger than those for residential programs).

    I've gotten two grants, one about seven years ago for a 1.3 kw system on our former house, and one last year for the 4 kw system for a larger house. I think the federal tax credit is 30% (but who knows what the House will do next).

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    Default Re: Solar power for the shop?

    Quote Originally Posted by Gib Etheridge View Post
    I don't see why you can't install a 100A breaker in one of those unused 220V positions and run the shop off of it. Run it by your electrician. Buy him a sixpack or two for having come in twice.
    I can only assume that there is something in the Electrical Code that would frown on 100 amp service feeding all the house circuits and a 100 amp subpanel. But I don't really know.

    My electrician friend won't need a six-pack, but some of my wife's cookies wouldn't hurt...

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    Default Re: Solar power for the shop?

    Quote Originally Posted by stromborg View Post
    My shop space runs off of a 40 amp sub panel. A one man operation just doesn't have to use all that much power, especially if as in the OP case of using a pellet stove for heat.
    I want to leave some capacity for upgrading my equipment later. Right now I run a contractor's saw and a wimpy 6" joiner; I'd like to upgrade to a full cabinet saw, the widest jointer I can find, and a planer with some real muscle -- and dust collection to match. I really want a good dust collection system. A pellet stove won't require much power, but the swamp cooler will likely run a 3/4 hp motor.

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    Default Re: Solar power for the shop?

    Quote Originally Posted by seedy View Post
    I took care of an off-grid home in AZ that had a wood shop in the garage, they used a propane backup generator, kicked on when the power dropped to a certain level. If you can build a sound-baffling room for one, a generator might be a solution. Diesel would be better, IMO, more bang for the buck, literally.

    If you want to try banking power and running off the bank, forklift batteries are a good value, but all this is getting up there in price. You'll still need an inverter and charge controller.

    BTW, I love NM, lived in the East Mountains for a while. Still miss motorcycling there.
    A fully off-the-grid system is beyond the capabilities of the budget. A diesel generator running in my suburban back yard would result in visits from Building & Safety and the Zoning Board.

    New Mexico is dual sport motorcycling heaven. KLR 650 getting prepped for the Continental Divide Trail this summer.

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    Default Re: Solar power for the shop?

    Quote Originally Posted by Ron Williamson View Post
    I have a 3hp table saw,some outlets and some lights running on a 50A sub.
    What else does one guy need?
    Serious dust collection.

    I'll admit up front that I'm a neat shop freak. Not white glove neat, but I truly loathe wading through knee-deep chips and dust while I'm working (to say nothing of breathing all that crap). I think and work better when there's a place for everything and everything in its place, and that includes sawdust.

    Maybe there's a 12-step program for guys like me...

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    Default Re: Solar power for the shop?

    Quote Originally Posted by Chip-skiff View Post
    The US Dept. of Energy has several programs that provide block grants to states for renewable energy incentives. In Wyoming the grants are administered by the Business Council. But if you search DOE - renewable energy grants - (your state), you should find some leads. Other sources are USDA rural renewable energy programs. If you use your shop for business, you might qualify for other grants (usually larger than those for residential programs).

    I've gotten two grants, one about seven years ago for a 1.3 kw system on our former house, and one last year for the 4 kw system for a larger house. I think the federal tax credit is 30% (but who knows what the House will do next).
    I'm all over this. But I think the Federal tax credits expired last year. The shop will house a part-time business (hopefully enough to pay for itself, at least), so maybe that can be worked to my advantage.

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    Default Re: Solar power for the shop?

    Quote Originally Posted by Desert Sailor View Post
    ...I'll admit up front that I'm a neat shop freak. Not white glove neat, but I truly loathe wading through knee-deep chips and dust while I'm working (to say nothing of breathing all that crap). I think and work better when there's a place for everything and everything in its place, and that includes sawdust...
    You better hope Lefty doesn't see this post.

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    Default Re: Solar power for the shop?

    2 hp dust collection will deal with a 24" planer(10-15hp).
    Would you get something that big?
    R
    Sleep with one eye open.

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    Default Re: Solar power for the shop?

    Like a few other posters, I run a really well equipped one-man shop on 60A. You could do nicely on 30 or 40 (the dryer feed) by: wiring everything you can 220, managing dust collection/saw turn-on to be non-simultaneous, maybe make a separate 12V lighting and battery charging setup, and use non-electric heat. If you run a computer, put it on a healthy UPS so tool start-up doesn't cause you problems. Also, if you're building something that will have 12 V ship power and 120 volt inverter power, get that stuff and use it now during construction, then transfer it to the boat when done. (Don't know your project, so this may not apply.) Your solar concept may fit nicely in this system. For several years, I ran an office trailer with many computers, pro videotape machines, monitors, and airconditioning off a 3kw Honda inverter generator. A UPS on the electronic stuff kept it running during the A/C startup draw. All worked fine. In the RV world, there's a device that prevents simultaneous startup of two air conditioners. This concept could be applied to the dust collector and air compressor, for example. Chip

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    Default Re: Solar power for the shop?

    Quote Originally Posted by Desert Sailor View Post
    I can only assume that there is something in the Electrical Code that would frown on 100 amp service feeding all the house circuits and a 100 amp subpanel. But I don't really know.

    My electrician friend won't need a six-pack, but some of my wife's cookies wouldn't hurt...
    This is what we have to power the shop/garage. No worries. With the right size wire and the proper size breakers, of course.

    Steven

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    Default Re: Solar power for the shop?

    Quote Originally Posted by Ron Williamson View Post
    2 hp dust collection will deal with a 24" planer(10-15hp).
    Would you get something that big?
    No. But I could see something a little bigger than a 12" planer, and a 12" jointer if I can find one...

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    Default Re: Solar power for the shop?

    Quote Originally Posted by TerryLL View Post
    You better hope Lefty doesn't see this post.
    Eh-HEM...... Lefty sees everything....... Everything.......






  28. #28
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    Default Re: Solar power for the shop?

    Quote Originally Posted by Chip Chester View Post
    Like a few other posters, I run a really well equipped one-man shop on 60A. You could do nicely on 30 or 40 (the dryer feed) by: wiring everything you can 220, managing dust collection/saw turn-on to be non-simultaneous, maybe make a separate 12V lighting and battery charging setup, and use non-electric heat.
    What I get from your ideas is that I need to put together at least a preliminary design so I can have a reasonable idea of power and startup loads. From there I'll know if 60 amps is enough, and whether it make more sense to try and rig a subpanel from the current main panel, or do something with solar.

    Without getting too far off topic -- the shop will be mostly for woodworking, hopefully have a boatbuilding project of some kind going on (SCAMP underway in the garage right now, but it's pretty crowded), the odd welding task, and a place to work on my KLR.

    Not to belabor the point, but I really do want sufficient, even excessive, dust collection. I'm tired of moving hoses between pieces of equipment, breathing in all the crap, and having a fine powder all over my hand tools, bench, lights, and everything else.

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    Default Re: Solar power for the shop?

    I've had a 3HP 4 bagger Grizzley dust collector. It's not the HP I like so much as the extra bags. I don't have to dump it as often.
    Last edited by Gib Etheridge; 05-06-2012 at 08:38 PM.

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    Default Re: Solar power for the shop?

    Quote Originally Posted by Desert Sailor View Post
    A major challenge is my electrical service. My 100 amp panel is tapped out, and upgrading to 200 amps with a subpanel to the shop would be $$$ -- back-of-the-envelope estimates from contractor friends are running $3k - $4k and possibly higher.
    At 3-4 grand, that sounds more like an acquaintance than a friend.

    Couldn't you run a bigger service wire (if needed), put in a 200 amp entrance panel and hook your present 100 amp panel into it on a 100 amp circuit breaker, and in effect turn the old entrance panel into a sub panel? Then run whatever you need out to the shop, using the leftover 100 amps on the new entrance panel.

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    Default Re: Solar power for the shop?

    Quote Originally Posted by SamSam View Post
    Couldn't you run a bigger service wire (if needed), put in a 200 amp entrance panel and hook your present 100 amp panel into it on a 100 amp circuit breaker, and in effect turn the old entrance panel into a sub panel? Then run whatever you need out to the shop, using the leftover 100 amps on the new entrance panel.
    I honestly don't know -- could I?

    Not being facetious. I can pull wire and run circuits, install a breaker, bend conduit if necessary (but it has been a while) -- but I don't have the skills to upgrade the main service wire.

    Is this a fairly simple procedure, or is this getting beyond the skills of the self-trained amateur electrician?

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    Default Re: Solar power for the shop?

    At a minimum you can run a fully equipped shop on 25 amps. But the machinery needs to be wired for 220, and no more than two 1.5 HP motors can be running at one time. You can have a ton of stationary machinery, and a ton of portable tools, but you can't run them at the same time, but who does? A 50 amp subpanel is completely adequate for a one-person shop.

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    Default Re: Solar power for the shop?

    Quote Originally Posted by Desert Sailor View Post
    I honestly don't know -- could I?

    Not being facetious. I can pull wire and run circuits, install a breaker, bend conduit if necessary (but it has been a while) -- but I don't have the skills to upgrade the main service wire.

    Is this a fairly simple procedure, or is this getting beyond the skills of the self-trained amateur electrician?
    Well, we went through this awhile ago when someone had electrical problems. It depends on where you live on what you have to do and what the power company will do. On most houses the meter is attatched to a pipe that goes up the wall and at the top is the masthead (I believe it's called) where the wires come out. That's the service wires you are responsible for, from the meter to the masthead. Once they come out of the masthead, that's where the wires from the pole/transformer are spliced to your service wires. You might have to pay for those wires that go to the pole/transformer, but usually the power company will do the hookup and splicing them together. You can call and ask. Anyway, if those wires from the masthead to the meter are too small, you have to replace them. If the old pipe is too small for newer, bigger wires you have to replace the pipe with bigger pipe. A new pipe, masthead, wire and meter socket aren't very expensive. Home Depot has that stuff (the power company might supply the meter socket)

    Looking at Home Depot, a SquareD 200 Amp outdoor entrance panel is $150 (indoor $100) and
    Includes 12 THQP-120 20 Amp single-pole circuit breakers, 1 THQP-230 30-Amp double-pole circuit breaker and 1 THQP-250 50 Amp double-pole circuit breaker
    A 100 amp breaker is $35. If you put it by your meter, all you would have to do is unwire your old panel from the meter and rehook it to the 100 amp breaker in the new box ( or skip the new 100 amp breaker and directly wire it to a sub feed in the new box, you still have your original 100 amp main breaker in the old box). Then run off a breaker in the 200 amp panel to your shop and a subpanel there. That way you don't have to tear up walls or even touch the old box or mess with the old wiring at all.

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    Default Re: Solar power for the shop?

    We have a main panel for the house and a separate 100-amp panel for the garage/shop/greenhouse, on a single meter, with a shut-off for each. In this state, a homeowner can do the electrical wiring and installation downstream from the shut-off. But it helps to know what you're doing.

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    Default Re: Solar power for the shop?

    It might just be me, but isn't this a whole lot of power? I know I run 240V, so only half the amps, but our main cirquit breaker is generous at 3x32 A mains (which you can't reach legally) splicing to 9x16 A, but it used to be a farm. A normal house will have just 1x32A main splicing to 3x16A accessible cirquit breakers. This talk of a seperate 100A group for the garage makes me think people are making their own aluminum there.

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