We are solar poweredWe welcome your thoughts & suggestions: notably it was your requests over many years regarding our energy and investing ideas that helped us to conceive the WilderHill Clean Energy Index® (ECO), the first Index on Wall Street for renewable energy solutions - now successfully run by WilderShares, LLC. Starting from a modest showcase of energy solutions and the first Clean Energy Index®, we're now working towards a broad and applied demonstration of renewable power in both buildings and transportation.
For example, we're harvesting considerable electric power from the sun, via solar PV (PhotoVoltaic = electricity generating) panels. This array is 'grid-intertied', meaning that our building is connected to the power-grid; during the daylight hours, we're generally making more power than we consume, and so we automatically 'sell' excess power back into the grid. Thus in daylight, our electric meter actually runs backwards. After sunset, it's reversed; we then 'buy' our power from the utility - and the meter runs the opposite way. We seek to make enough power during daylight, to make up for night, and to have a zero utility bill. Grid-intertied means we're connected, able to avoid the cost of batteries, and it permits rebates from the State of California. As shown next, for cost breakdown, the system performs well in cost/benefit projections, return on investment, and in practice. This 3.85 kilowatt (kW) solar PV system is calculated to achieve payback, in approximately 7 - 10 years (see solar PV system costs). That reasonable time to payback, is due *to California State solar PV subsidies cutting the PV system's original costs in half, *to coming time-of-use (TOU) metering by our utility that allows us to 'sell' electricity at an attractive rate, and *to a California tax credit. Certainly, the upfront costs for the whole PV system were significant. These costs were $15,000, but California subsidies and tax credit meant that we only paid about half of what the system would cost, without those benefits. We've estimated that after generating solar power for 7 - 10 years, we'll recoup full return on investment, and so thereafter most of our electricity is made at no charge. That stability contrasts with dynamic local utility rates that usually go up over time. Smartly, our fixed cost and equipment will go on helping us, for many years, after cost amortization. Solar panels are the main cost here, and they carry a manufacturer's Warranty of 25 years - notably, a longer life should be expected from these panels, given the performance seen from panels in use over decades. The 3.85 kW Inverter carries a shorter life of perhaps 7 - 10 years and will have to be replaced. We expect years of profitable PV operation and thus feel without any undue sentiment, that this can be a sensible return on investment. This system has performed without a hitch. In 2003, we installed the 21 then-new Sharp 185 watt panels (see spec sheet) in three strings with each panel at a 14.2% efficiency rating. These panels were made in the USA, and were then among the most efficient of any PV consumer product, employing a rather unique and power-dense mono-crystalline design. These panels were matched to a Sharp Sunvista 3,500 watt inverter (along with two web-based real-time monitoring systems) in one of the first such installations in California. As illustrated by daily monitoring data in detailed graphs, we've been obtaining module efficiencies of roughly 5% to 10% over the manufacturer's rating. Inverter efficiencies are also measurably high, and in Spring through Summer months we can generate over 20 kilowatt hours per day. During Fall or Winter months, with fewer daylight hours, the sun much lower, and less irradiation overall, we may generate well less than half that amount.
Besides the PV that's used to make our electric power, we also use two independent solar water-heating systems. Both are thermal, and so they rely instead on simply collecting the sun's warmth to heat water. First there's one system that's completely passive and doesn't require pumps, thus increasing overall efficiency; this also extends expected system life. It provides daily hot water for our home/office, in a roughly 2,500 square foot building. The second thermal system, is used for heating a large pool. Currently the system relies on an existing one horsepower pump already filtering the pool, since that pump can on sunny days circulate water through the panels too. The pump is powered by the home PV array + inverter, to move water through 400 square feet of thermal panels (10 panels that are 10 foot by 4 foot each), heating the pool significantly Spring to early Fall. Throughout the summer, the pool generally stays around 87 degrees F due to this solar thermal heating. But that AC pump, which is on for many hours per day, is a large consumer of home PV power.
We closely monitor our building energy demand - as well as solar power generated - because it's as useful to reduce our demand, and so avoid a need for power in the first place, as it is to make energy renewably. Energy demand is thus displayed live above. While these surprisingly simple efficiency steps that we'll advocate for, may be given less public attention than innovative ways to make power, we believe there's ample reasons to act first to reduce the need for power. Many solutions we've adopted are indeed compelling for their very simplicity, and widely repeatable. Among these easy, reproducible steps are:
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