Since 2003, my husband and I have been living off-grid on the Hamakua Coast of the Island of Hawaii. We feel good about the footprint we are leaving on this planet and we have no utility bills, saving roughly $250-300 per month for us. And when we generate more power than we use, we can offload our excess power to heat the water in our hot water tank or to charge electric vehicles.
Off-grid living used to be considered an alternative approach to power generation, but we believe it is the preferred approach for the rural island lifestyle. In many cases, properties that are energy self-reliant are now understood by conventional real estate appraisers as possibly having greater value than conventional utility company powered homes, recognizing, of course, that value is determined by the quality of the installed power generation system.
In east Hawaii, rural properties not close to a power pole increased in number when the sugar plantations closed and sold off parcels of land. Off-grid systems have become more and more common as homeowners have selected these systems when faced with the cost connecting to the grid. Additionally, homeowners are taking advantage of tax credits to install photovoltaic systems even though their homes are connected to the grid. By “intertying” these off-grid systems to the grid, these homeowners benefit by reducing their on-grid cost while having full grid power availability.
A Brief Introduction to Power Generation Systems Used on the Big Island
Solar, micro hydro and wind are the three main types of off-grid power generation systems used on the Big Island, with solar capturing the greatest market share simply because it is easy and because not every home has enough wind or a stream source. While the Island of Hawaii has an abundance of sun, wind and fresh water, the best locations for stream sources are in East Hawaii. It is not uncommon for off-grid users in East Hawaii to have a combination of solar and micro hydro systems to ensure consummate power generation, rain or shine.
Solar: Solar technology continues to accelerate with new developments – greater efficiencies in the solar collector, higher wattage collectors, smaller collectors, and more. As long as the sun shines or the clouds are not too thick, these collectors will generate power, but only during the daytime, and mostly during a 5-8 hour stretch, depending upon the season. What’s nice about solar is that the systems are quiet and they do deliver the power required to run a household.
Micro Hydroelectric: Most homeowners don’t have a stream with enough drop in elevation (head) or volume to install a micro hydro system. However, if a micro hydro system can be installed, this system will provide 24/7 power generation (as long as the stream is flowing with enough water). Without getting too technical, a properly installed system can reasonably generate 12-18 kilowatts of power per day, enough to power an entire household in a normal manner. If the water flow is year round and is of significant volume, multiple penstocks (pipes that carry the water to the turbine) and turbines could be installed to increase the generation capability. This type of power generation mixes old technology with new technology and is tried and true.
Wind: Wind generating turbines are probably the second most common power generation system after solar, and deliver quality power when installed properly. Most common turbines are vertical and are elevated to capture the wind.
Batteries: Nearly all off-grid residential systems rely upon batteries to store and deliver the generated power. The typical residential off-grid system does not normally generate enough power at all times that power is desired, so these systems store the generated power in battery strings capable of delivering enough power to satisfy the expected loads. Although expensive, when maintained properly, batteries can last 10-15 years, depending upon the loads, number of cycles, and other factors. Amp-hour capacity is a critical component of battery system design.
Inverters: With today’s technology, inverters are extremely durable and dependable in managing the conversion of DC generated power to AC delivered power with ease. Inverters such as the Outback brand also are designed to resist bug intrusion into the electronic components. Inverters can be stacked to manage greater load capacity.
Backup generation: Whatever your primary source of power generation is, it is always a good idea to have backup generator. There may be many reasons why your system will be down (e.g. maintenance, drought in the case of micro hydro, multiple days of heavy rain and cloud cover in the case of solar, etc.) but that does not mean you have to be without power. A combination of power generation systems is a basic staple of any well designed system. Most solar systems use a fossil fuel backup generator that starts up automatically when the batteries get below a defined threshold.
These are the basics of any off-grid power system. If you are considering purchasing or selling a big island property with off-grid technology, please contact me. I look forward to telling you more about off-grid living.