Shop Equipment

We have most of the usual home shop tools, plus plasma cutter, stick, TIG, and MIG welding equipment. None of it has posed a problem for the power system. The largest load used often is a 4-hp air compressor. The startup draw of its motor can’t be taken lightly. If it were to start during heavy welding, the total load might be too much. So I try to remember to shut off that compressor when welding to avoid that. We also have a smaller air compressor that doesn't have the same potential to cause a problem, and I use it most of the time. I run the welders off the inverters for light work or short beads at higher current settings, which has not been much of a limitation.  On the wind-power page you'll see a tower that I welded almost entirely (over the course of some weeks) with our setup. Only a few of the welds required switching to the engine driven unit.  About the only other thing in the shop that’s a little different is an in-ground car hoist. This makes the compressor work pretty hard for several minutes but the system handles that without complaint. Most of the power tools are used only for short bursts. There are some exceptions, perhaps the table saw or thickness planer might be left running for extended periods on a larger project. If such loads will deplete the batteries more than the sun or wind can replace by the next day, then the engine driven generator can be run at the time of use or later. So the shop is pretty much like the house, no real problems, but supervision required.

Miscellaneous

Several minor appliances use a fair amount of power, but only for short times. These include the garage-door opener, the central vacuum system, the toaster and  kettle, and the ventilation fans. A few others use small amounts of power for extended periods. These include the X-10 timer controller and its modules, the safety circuitry on the garage-door opener, the radio telephone, cordless phones, and the water softener if left in automatic mode. 

Idle Loads

These are the ghost loads, things like the energy use of a VCR when it’s turned off. It’s just a little trickle of power to keep the clock alive and to allow the unit to respond to the remote control. But a modern house has a whole bunch of these energy wasters and they can really add up. Plus, the inverters themselves eat a little power even if no appliances are being used. In smaller systems there's no choice but to eliminate these loads, and some people go to great lengths to do that. We got rid of a few. We put an extra switch on the cook-top and most of the home theater devices. We put the solar water-heating controller, and one ceiling fan on timers.  But all the other little energy wasters can’t be comfortably eliminated so we’re stuck with them. The same will be true with most systems to varying degrees, so if you’re designing one make sure you allow for it.

Problems in Paradise

It seems like we had more than our share of problems.

The new inverters refused to talk to each other right out of the box despite the fact that they had consecutive serial numbers. It took a few calls and a couple of parts shipments to straighten it out. Later, for no apparent reason one of the inverters failed. It turned out that a small grasshopper had crawled inside and shorted out the works. I returned only the damaged circuit boards and it was taken care of under warranty.

The true sine wave inverter had a problem with its reset switch. The cooling fan directs air over the internals including the switch. The switch isn't sealed and eventually needed cleaning. This will be a recurring need unless I replace it with a different switch.

There were minor problems assembling the solar tracker racks. Later there were several problems with the tracker controllers, and eventually they were replaced with a newer design.

Early on the system monitor kept resetting itself. It was replaced several times under warranty, the last time with an improved model and it worked well for several years. Now it's acting up again, although it's still useable.

The vacuum-driven fuel pump on the welder-generator proved to be inadequate to use with a remote fuel tank. I replaced it with an electric one, and found out later that the manufacturer had published a service bulletin advising everyone to do the same with this model.

We started with an odd-ball well pump. It was supposed to be ultra compact and highly efficient, with a softer starting load. It turned out to be just plain delicate, and it didn’t like inverter power much. It failed twice, then we replaced it with a conventional one and have had no further problems.

The worst problem by far was with the small wind generator. This was a new design and it simply wasn't ready for prime-time. The manufacturer kept sending parts but these only cured the symptoms not the disease. After four years and several failures I was ready to just throw the thing in a hole and bury it. The company convinced me to send them another $100 to update it to their improved specs and we did that. It has run for about four years now without further problems. 

Some of this hardware has matured considerably since we bought ours, so I wouldn’t expect anyone purchasing similar components today to have as many problems. But don’t expect to buy a bunch of complicated hardware and get away without a single hiccup either.

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