Achieving a comparative immediate payback on investment through solar electrification of a detached workshop.

Achieving a comparative immediate payback on investment through solar electrification of a detached workshop.  

In the long list of things I should have done years ago, I should have added a micro-solar electricity generating system to my workshop.  Lighting, air tools, a compressor, electric tools, saws, grinders, a computer, a heater,  everything I needed to do projects easier and extend my work days, all of it depended on electricity. For years I had been "making do" by running dangerous extension cords and performing much of the work on my front porch.  Finally, enough of that!

So inspired by a long time friend of mine who founded a company installing serious and professional grade solar generation equipment in far-away places where electricity grids are really needed, I thought I would devise from scratch a much smaller system for myself. What I needed was something big enough to run a heater or a circular saw and yet small enough to keep the cost below my alternative: having an electrician come out to the property to install a pole and run an electricity line out to the workshop.  After the hypothetical pole installation, the line hanging, the panels, fuses and junction boxes, this alternative would cost several thousands, not to mention the permitting and ongoing additional electricity cost each month. 

So I believed at the time that a cost effective solar installation would have to be justified based on the ongoing cost of the electric bill I would save, with a payback that I hoped would be less than ten year. This ten year payback was what I had been told to expect when we lived in Germany, where almost every building has solar installations. Can't blame me for believing that I would probably not be able to install a micro-micro solar option for much less than the price of the alternative initial investment in running the electric line. 

What I had not known at the time could have filled volumes. After lots of reading and experimentation, I now have a 4 kilowatt solar system, plenty of juice for shop lighting, a computer, and tools that run one or two at a time, tools like saws, compressors, grinders, nut drivers, drills, and diagnostic equipment for my shortwave radio experiments.  And I have not yet depleted my battery bank though I have worked five hour shifts here in the grey days of Pennsylvania December.  Amazingly, even with all new equipment, purchased online and from big box hardware stores, my costs for this micro-micro system was about SEVEN HUNDRED DOLLARS.  When compared to my alternative method of electrifying a workshop, I had an instant payback!

What had I been waiting for all of these years? 

Here is a hand drawn wiring diagram of what I pulled together:*

 

Some of the equipment:   The solar panel now mounted on the front of my workshop. 

The power inverter, converting DC 12volt power from the batteries into pure sine wave 115volt AC. Below the power inverter is a solar controller, a little box that protects the batteries from over or under charge and keeps the batteries healthy in all temperatures and charging situations. 

The whole thing is shown below. Even with both batteries the equipment is smaller and lighter than the equivalent gasoline generator (there on the floor under all of the extension cords).  That gas generator is a carbon emitting hog, inefficiently converting lots of petroleum into a little electricity and big clouds of smog and noise.  The gas generator is so loud, in fact, that I can't work near it when it runs.  But my new micro-micro solar system is silent and a pleasure to use. 

In the event of any future protracted power outage, I will simply move the power inverter and one of the batteries to the porch where it will provide indoor lighting, power our computers, and keep the freezer freezing until the power gets put back up. 

Next project: figure out what to do with the old gas generator. I thought about making an irrigation pump out of it. But then I realized my power inverter could run an electric semi-trash sump pump placed in the lowest of our rain barrels. That would pump collected rain water up the hill through a garden hose into another hill top barrel. From there gravity would irrigate the gardens and fruit trees on that high slope end of the property. Any ideas on what to do with this old generator? 

*  This initial drawing is missing two important pieces of information. First, the wire is all twelve gage, 3 strand, copper housing wire (except for the 4 gage jumper cable running between the batteries.)   Second the center strand is ground, starting at the frame of the solar panel and running from there to the switch housing, to the frame of the power inverter and then to a grounding post driven into the dirt right outside the workshop door.