I'm building a outbuilding (barn/shop/etc) about 1000' from the nearest utility power.  The cost of extending the power to my building is going to be largely on me, and while I don't have the final numbers, it looks like we'll easily be in the $12k-15k range just for the power line extension.  I probably don't have the flexibility to lower costs here.

So this has me thinking Solar.  My typical power requirements are probably fairly modest.  I'd have barn fans and lighting, an office area with AC, heat, a small refrigerator, microwave, computer, tv, some other stuff.  Fairly typical.  So for this portion of the electrical load I think Solar is a good option,  The only real concern is the AC, but a mini split will probably get me into the 1500 watt range.  Hopefully I can keep my kWh in the 500 range per month.

However, I will on occasion have some fairly massive power requirements for 1-3 hours.  We're talking 10,000 watts.  So for this occasions, I was considering a generator.  It would allow me to keep the solar part of the system fairly modest, while providing me power to charge batteries or power my heavy load.

It seems like the generator will allow me to keep the Solar scale down some and hopefully cost a bit less.  It will likely be a propane generator since I'll have a tank of that for heating anyway.


I'm I thinking clearly here?  What should I consider?

solar is pretty expensive still.

wind is cheaper by far.

if your area has enough wind I would consider that route.

either way, I think you will have some battery/storage expense, during rain or after dark.

I did a bit of research a while back when they started offering home systems.
vertical windmills seem to be the best choice per kwh.

Many of the large inverters for off grid solar will have a generator start feature.  You could install the battery bank, inverter and generator and be done with the setup for far less than the price of a solar setup.

For your setup two generators may make more sense, a small one for the regular battery charging, and a larger one for the big loads the inverter could not handle.  Two generators would likely run more efficiently, and would allow you to use a smaller inverter.

You could upgrade that setup later to add solar or wind whichever made the most sense.  The wind may need a dump load, but that can often be very simple and cheap and think some charge controllers will already be setup for the dump load.

Not sure I'd get much of a charge from wind here.  I'll have to check,  I remember seeing wind potential maps of my county, that mostly showed marginal spots on the ridges.  I'm in the valley somewhat and lower than the properties to the north and west and south for that matter.

I like the two generator idea.  10k or more for panels will buy a lot of fuel

Cheapest Online Solar I've ever found

There were some small system "examples" on here somewhere.

I tried the numbers for myself and a dozen times for projects at work.   Solar rarely works and there usually must be a lot more power line to even start the discussion

When looking at the numbers, in addition to the initial outlay, solar has a high cost of ownership. As a general statement, the cheaper the battery you buy, the more often you will replace it. A three year life span until your down to 1/2 the original capacity is a good ballpark to start with. I have tried several projects where the replacement cost of batteries alone exceeded the saving in electric cost.

Will your shop be heated 24/7 in the winter?  If not, you will need to apply a temp derating on the batteries. At 32 def F, you will have to derate by 20 - 25% (slightly offset by solar panels being more efficient in the cold)

All that said, I have a fiend (former in-law) that has a nice cabin in NE NM that is solar + auto start generator.  I did the design and almost all the installation work. He spent over $35K on the entire setup, including the added cost of all LED lighting in/outside,  high efficiency AC, duel fuel refrigerator, and quite a bit of top shelf whiskey.  (He would have been looking at almost 5 miles of power line).  The genset cranks whenever the water well pump needs to come on, but anytime it does run, it is also charging the battiers.  It will also start if senses battery voltage falling too low.  The system runs on two inverters...one unit that is very high efficiency, low idle current, which runs the "normal" loads.  The larger inverter must be manually turned on (there are several start button inside and out) for outlets dedicated to the microwave, washing machine, big draw kitchen appliances, window AC unit, and the like.  It times out after 15 min of no current drain.

Don't forget the cost of a safe means for fuel resupply and fuel storage, the cost for installing a generator (pad, wiring, transfer switching, etc), automating the generator start-up, etc.  

Do you have a means of synchronizing the generator output to the inverter output?  Is the inverter output compatible with the generator output?

The one pallet minimum is 2,520W and costs only $857.

To obtain 500kWh/month, I would guess the OP needs well over 3kW but this depends on where he lives and the number of hours of sun he gets per day.  It also depends upon the particulars of the site and installation.

Don't hope, think!

Make a list of all the loads you will need to feed.  Add their power consumptions to determine your needs.  Use the nameplate power consumption ratings.

Under-sizing the system would be a big mistake.