HERE ON THE BIG ISLAND: Could You Live Off-the-Grid? Part III: Here Comes the Sun

HERE ON THE BIG ISLAND

By Kelly Moran

Could You Live Off-the-Grid?  Part III: Here Comes the Sun

          Turning sunshine into electricity is the most popular way to generate your own power, here, although two conditions must be met.  First, you really have to have a good view of the sun all day: no trees or hills shadowing the house.  And second, you have to have dough: the initial investment is high, and likely to remain so for the near future.  A “family-of-four” will probably need a system costing $30-40,000, including batteries and control equipment. 

          But electricity from the Hawaii Electric Light Co. (HELCO) costs more than 30 cents per kilowatt-hour, pushing utility bills up into thousands of dollars a year, and the rates will only go higher.  So, a solar system should break even in ten years or less.  Moreover, the price of photovoltaic panels is slowly coming down, while their electrical efficiency keeps going up.  And there are no ongoing costs: once the system is in place, your electricity is free, and your batteries get charged up every day!

          Two recent technological developments make solar increasingly attractive. The newest photovoltaic collectors aren’t like heavy picture-frames, with glass on top.  They’re lightweight, flexible sheets of plastic that are available either as shingles or as peel-and-stick strips that lie flat, between the ridges of standing-seam metal roofs.   And these new materials are more sensitive to ultraviolet light than the glass panels are, so they keep on making electricity even on cloudy days, when there isn’t as much “visible” light.

Two ways to Capture Sunlight:

"Building-integrated photovoltaic" (BIPV) panels adhere directly to a standing-seam metal roof.
"Building-integrated photovoltaic" (BIPV) panels adhere directly to a standing-seam metal roof.
Framed-glass photovoltaic panels are mounted on a carport.
Framed-glass photovoltaic panels are mounted on a carport.

          If your land is close to an existing utility pole, the Hawaii Electric Light Co. (HELCO) may accept whatever electricity you generate and, in effect, store it for you in its grid.  But hey! – this is about living off the grid.  And that means storing your electricity in batteries.

          The right kind of batteries for home-size power-plants are similar to car batteries, but larger and heavier, with higher electrical capacity (24- or 48-volt, instead of 12).  And their installation has to meet building codes (e.g., you can’t put them in the crawl-space under the house).

          To keep your system operating at peak efficiency, you will have to take on some responsibilities that have traditionally been shouldered by the utilities.  Though you don’t have power-poles to climb, or high-tension wires to string, you will have to perform some regular maintenance tasks, the equivalent of those that utilities ordinarily do, and the cost of which they bundle into their monthly bill.

          So, for example, you must ensure that the fluid in your batteries is at the proper level, by topping them off with distilled water, once a month.  And as soon as you do that, it’s a good idea to run your backup generator for at least an hour or two, not only to help your batteries stay fully charged, but also to keep the generator itself in top running condition, so it’s always ready in case of emergency.

          Go solar, and you also ride the wave of the future.  If we in Hawaii are ever going to free ourselves from imported petroleum fuels, we will have to generate more and more of our electricity from the sun.

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HERE ON THE BIG ISLAND: Could You Live Off-the-Grid Part II: (Electric) Power to the People

HERE ON THE BIG ISLAND
By Kelly Moran

Could You Live Off-the-Grid Part II: (Electric) Power to the People

In my discussion of catching rainwater, last time, I neglected to mention that in some places it’s possible to draw water from a well, especially if your land is near to places where Hawaii County draws its water. But finding a reliable and sufficient source of water underground is not easy, and on the drier, western side of the island, wells have to be drilled very, very deep. So, you may get lucky. Or not. And the cost of drilling could exceed the cost of a catchment tank. Besides, a well needs a pump – and that means you need electricity.

There are four ways that people here generate their own electricity: fuel, wind, hydro, and solar. I’ll cover the first three now, and discuss solar next time.

  • Fuel. By far the easiest way to get power is to buy a generator, keep it stocked with whatever it burns — typically either diesel or propane — and run it until your batteries are charged, roughly six hours a day. With either fuel, you can assume that your electricity will cost a few hundred dollars a month — about what you’d pay Hawaii Electric Light Co. (HELCO), the local utility. Generators are not expensive, but you should balance that low initial investment against the certainty that the price of fossil fuels will keeping going up, even if renewable alternatives like bio-diesel or methane enter the mass-market. (No matter how you make your own power, if you live off the grid you should have a generator anyway, even if it’s only a portable gasoline model, for backup or emergencies.)
  • Hydro. If you have a good-size stream on your land, a hydroelectric turbine may be the way to go. The machinery is not very expensive, and you do not need a waterfall, as long as the water level drops at least 40 feet from the intake point down (through a pipe) to the turbine. But the stream has to run year-round, and in a drought lasting several weeks, even some large streams may shrink or dry up. Ironically, the only serious disadvantage to hydro is that under normal conditions you may get too much power from it! Unlike breezes or sunshine, streams run 24/7. After your batteries have been fully charged, any excess electricity can damage your system: it must either be stored (in yet more batteries) or consumed immediately. One fellow I know had to buy a chest-freezer and an air conditioner solely to soak up all the electricity from the turbine in his stream.
A stream this big could genereate electricity, but only if the water level drops 40 feet or more from the intake point down to the turbine.
A stream this big could genereate electricity, but only if the water level drops 40 feet or more from the intake point down to the turbine.

 

  • Wind. A small windmill may generate enough power for a barn (or a well-pump) but a windmill sufficient to power a household must be quite large, and hence expensive. On this island, that’s a viable option only if your land is really windy, which you’ll know because your trees are bent over, as they are near HELCO’s “wind farms” — clusters of turbines – -at the northern (Kohala) and southern (Ka’u) capes. On the Hamakua Coast, the onshore tradewinds are not constant; and on the Kona coast, daytime breezes tend to die down at sunset.

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