Noob with just enough knowledge to be dangerous has a question...

Trees are the enemy of solar, and they keep growing taller (ask me
how I know). On these very hilly 5 acres are thousands of feet of
buried cables, for power and communications. Use of direct burial
cable has made this economical and straightforward, the only serious
cost being digging the trench. That I limited to $3k with my very own,
oft used trencher. Details in my past threads.

Electric motors are a big problem for off grid, starting current for an
induction motor could peak at 5 times full power running current.
That for a saw or cheap air conditioner. A shop could be run using
largely battery powered hand tools (charged where there is grid)
and starting up a gen set for big tools such as welder, car lift, saw,
etc. A direct driven alternator can use some of its own inertia to
help with motor starting, an electronically controlled inverter set will
have difficulty doing this.

Battery/solar can work, but will be extremely costly to do the above.
Detailed knowledge of the loads would be needed.
good luck, Bruce Roe

While most "motors" draw high inrush currents I would not figure using a solar/battery system to run them or even a small AC unit. It just doesn't work that way.

To size a solar/battery system you really need to know how many watt hours you will consume on your worst day. Then you can calculate size of your battery system. From there you can determine your solar panel wattage. Now remember the amount of wattage you size for the winter will be higher due to a lower sun.
You will also need to replace the batteries some day and that will get expensive if you want quality batteries. You should forget about 12V batteries because to size a big system you will need to wire them in parallel which can cause them to die quicker.

I know you said the shop is far from the house but IMO I would still get pricing to run power to it instead of going solar. It may be cheaper in the long run.

As far as the idea of checking into the cost anyway, regardless of the distance from the main house to the shop, let me just fully disclose, there really is no more room on the main panel anyway. There is ONE 20amp circuit I could append to from the outside GFI outlet. It only has 6 outlets on that circuit, plus an attic ventilation fan. But all that aside, I just really want a solar system from my shop just to say I did it.
So far, I have:
Table Saw - 1800w
Small window A/C unit - 800w
Shop Vac - now, this is confusing. I know amps x volts = watts, so a 12amp motor x 120v should draw 1440watts.... so why am I getting this info straight from the Shop-Vac website?
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How can it only be 345watts?
lights- (3) 30w LED shop lights - 100w
Compressor 1.7Hp - 1270w
Band saw - 700w
really, nothing else will rise to the level of the table saw and the shop compressor


I will wait and run a total after some of you have a chance to school me on that shop-vac watts question. What does "peak air watts" mean???
I spoke to a Delta (table saw) technical support dude over the phone yesterday specifically to ask about start-up loads. He said they list start-up load info on their bigger shop table saws, but not the model I was asking about. The Delta 36-725t2.

Assuming I should just take the biggest motor on the list and multiply by 2.5. According to this website:

It looks like for the most part, they are considering startup wattage to be roughly 2 to 3 times running wattage.

So: 1800 for the table saw x 2.5=4500w. So if I got a Renogy 24v 3000w PSW inverter, for instance, it says it has a peak capacity of 6000w.

I don't know... I may need to look at the table saw, compressor, the shop vac, window A/C, and lights all running at the same time, plus one of them at start-up wattage.

I believe the "peak air watts" is the amount of wattage the vac draws when it is running continuously. The 12 amps may be the rating it can handle on a start up but the amps is lower when it is running.

Now that you have the wattage of each item you have to determine the number of "hours" they each run and then total the number of watt hours. That value will get you closer to sizing a battery system.