FIELD NOTES: Solar Is Everywhere and Nowhere

I received a Science Fair 20-in-1 Electronics Project kit for Christmas one year in my early teens. It consisted of 15 "blocks," each with a component like a transistor or a diode that could be wired together to create projects like an oscilloscope, rain alarm, or diode radio. One of the blocks was a solar cell about the size of a postage stamp. It produced very little power, even in direct sunlight, but it did demonstrate that electricity could be generated directly from the sun, a technology that was getting a lot of publicity in the early '70s.

The mass market "technical" magazines of the day, Popular Mechanics and Popular Science, featured articles about the exciting future of solar energy while acknowledging several hurdles to overcome before it ever became a mainstream power source. Those publications were sure, however, that advances in photovoltaic (PV) cells and electric storage would make solar energy ubiquitous by the turn of the century. In some ways, those predictions were correct, and in some ways, they were very wrong. 

Solar power is everywhere today, with retail outlets from the Dollar Store to Nordstrom's selling devices powered exclusively by the sun. Consumers have many solar gadget options, from inexpensive path lights to twenty-dollar solar phone chargers to pricey solar generators capable of running multiple appliances for several hours.  

But for all those lights and chargers, very few Americans derive a significant portion of their electrical needs from the sun. In total, less than 3% of electricity in the United States comes from PV solar panels, most of which is generated on large solar farms that feed the grid. Although one in thirty American homes have solar panels, residential solar accounts for less than 1% of electric production, and entirely off-grid homes powered exclusively by solar are extremely rare. 

It's a significant dichotomy; solar has never been more available or affordable, yet few choose to rely on it. The reason is simple. Despite the arguments and objections of solar proponents, the old saying "it don't work when the sun don't shine" remains as accurate today as it was in the '70s. If your path lights don't come on after a few cloudy days, that's one thing. It's another thing entirely if your refrigerator or heater kicks off.

I've been thinking about solar lately. I recently acquired some "retirement" property in the mountains, and while the local electric cooperative services the site, I am a couple of years away from building my dream cabin. In the interim, I want to have a small structure (think storage shed) where I can go up for a weekend and do some fishing and hiking. I don't want to pay to have this temporary shelter connected to the grid, but I would like to have lights, a small fridge, and a microwave. After a bit of research, I determined that my best option is a solar generator. 

These devices, which range in size from a toaster to a large cooler, have all the components - PV panel, AC converter, and storage battery - needed to provide a temporary supply of electricity for off-grid use. Starting around $500, these devices are rated by running watts, watt hours, and watt input. 

Running watts are the highest electric drain the unit will support continuously. Most microwaves, for instance, draw either 700 or 1,100 watts. In order to operate a 700-watt microwave, you would need a generator rated for at least that much.  

Watt hours refers to the storage capacity of the system. A generator rated for 1,000 watt hours would be able to run that 700-watt microwave for about 90 minutes. Of course, you don't operate a microwave for an hour, but you get the point.

Watt input is the wattage the generator can accept from the solar panels. A system rated at 400 watts will take input from up to four 100-watt panels or two 200-watt panels. The higher the input, the shorter the recharge time. On a sunny day, a 1,000-watt-hour system with a 400-watt charge capacity attached to four 100-watt panels would recharge the battery in just a couple of hours. 

To run my primitive backwoods system, a 60-watt mini-fridge (running continuously), 700-watt microwave (10 minutes per 24 hours), and 20-watt LED light bulb (2-3 hours per 24 hours) with occasional phone charging, a 1,000-running-watt generator with 1,000-watt-hour battery should suffice. Such a generator costs about $1,300 with a 100-watt panel.

Although I will keep the solar generator around as a back-up, I will almost certainly connect the permanent cabin to the grid. For a couple of select days each month (and unlikely to be days when it's raining) solar storage makes sense. As a permanent, reliable power source through rain, sleet, and snow, not so much.