Renewable Energy 101 - A Beginners Guide to Solar, Wind, and Energy Efficiency
What are my options and will it work?
We hear it all the time - Will solar power work in Alaska? The answer is yes, solar power does work in Alaska. In fact, it works very well in most locations with proper design and siting. Take a look at this map of the US showing solar power insolation in the month of March:
As you can see, during the month of March, interior Alaska receives as much sunshine as 2/3 of the Eastern US. From April to August the number is much higher because of our 20 hours of daylight. The annual average for Gakona, Alaska is approximately 3.5 sun-hours per day (3.5 hours of sunlight per day, averaged year-round). If an active tracking system is added to the solar PV array, the numbers are about 30-50% higher during the peak sun months. Due to the low angle of the sun in mid-winter trackers make little difference in winter. However, solar power remains one of the most under-utilized sources of renewable energy in the State currently. The lack of a State Net-Metering law and renewable energy incentives doesn't help either. Little by little, change is coming to Alaska. Federal tax credits are still available for solar and wind power installations through 2016. Up to 30% of the total cost of a solar or wind power system can be used as a tax credit, with no monetary limit. Consult your tax professional for details on the IRS Renewable Energy Tax credits.
Wind power remains another strong renewable energy resource in the State of Alaska. The highest winds are found along the coast and near inland mountain ranges. Take a look at this map of Alaska showing wind resources at 50 meters:
Wind is an ever-present natural resource along the Alaska coast. There is a vast amount of untapped power available in strong winds aloft. To take advantage of them, one only needs to turn toward the sky. Modern wind turbines are easy to install, require little to no maintenance, and are fairly quiet (except in gale-force winds). Residential wind turbines are available in micro versions from 300 to 500 watts, up to medium versions from 1KW to 5KW of power output. The rules of wind still apply - put the biggest rotor on the tallest tower you can afford to install. The old wind turbine saying "more tower more power" still applies today.
Components of a Solar PV System:
A solar power system (Solar PV system) consists of a group of key components necessary to convert incoming sunlight into useable AC power for your home or business. These components are:
Solar PV Panels (modules) - Solar panels today come in two main types; mono-crystalline or multi-crystalline. There are also new thin film panels in development, but they are of little use in Alaska so they are omitted here. The solar panel converts incoming sunlight into DC (direct current) power. Solar panels are rated according to their power output, voltage, and style. Grid-tie solar panels are usually higher voltage than off-grid solar panels.
Charge Controller - The charge controller is used in battery-based solar power systems only. In a grid-tie system without batteries, the DC power produced by the solar panels goes directly into the inverter. In off-grid and grid-tie systems with batteries, the charge controller regulates the power produced by the solar panels to properly charge the batteries and prevent overcharging. Without a charge controller, the batteries would continue to receive a charge even when fully charged - leading to catastrophic results.
Inverter - The inverter is the "heart" of any solar power system. The basic function of an inverter is to convert DC power from the batteries (or from solar panels in a grid-tie system) into AC power which is used by modern homes. Inverters are different between off-grid and grid-tie systems, and cannot be used for both. Modern inverters are "pure sine wave" meaning they produce clean AC power suitable for use with computers, TV's, appliances, and home electronics. Be wary of cheaper inverters which often produce "modified sine wave" power. You may find that your TV will not turn on. Inverters are rated in maximum output (watts) which is determined by your maximum household electrical load. Renewable Energy inverters are available in 2000-7000 watt versions.
Batteries - Renewable Energy batteries are different from "golf cart" or "deep cycle" batteries because RE batteries can survive frequent discharge cycles common with solar power systems. Inverters can demand 200-400 amps of power from a battery bank depending upon the load, which can quickly kill smaller batteries. Batteries are available in flooded lead-acid and sealed AGM versions. Lead-acid batteries are the most common in use today due to cost, but they do require frequent maintenance and watering. Sealed AGM batteries do not require maintenance and are sealed for life. Renewable Energy batteries are rated in amp-hours (AH) at a 20 hour discharge rate. Some advertisements do not quote the 20-hour rate, but rather the 50-hour rate which will often be higher. Once installed, a battery bank should not be upgraded as doing so will only degrade the new batteries.
Balance of System (Fuses, Disconnects, Wiring) - This is a very important part of any renewable energy system which is often overlooked during budget discussions. Don't forget to include proper AC and DC disconnects, circuit breakers, fuses, and heavy-grade DC wiring. Some manufacturers, such as Midnite Solar, produce integrated enclosures which include all disconnects and wiring in one easy-to-install box. When evaluating wiring, go with the highest quality wiring you can purchase. Battery cables should be 2/0 or 4/0 stranded copper wire (we prefer Arctic Ultraflex). Solar panel wires should be sized according to the length of run from your home to the solar array. Also don't forget proper DC disconnects at the solar array!
Components of a Wind Turbine:
Small residential wind turbines are available in micro versions (3 feet diameter) up to medium size turbines (15+ feet in diameter). In general, larger wind turbines will produce more power at a given wind speed due to the larger swept area (the diameter of the blades which sweep the wind). There are very few components in a wind turbine:
A wind turbine includes the hub, blades, and generator. The tower is normally a separate purchase, based upon your site-specific requirements. As a rule of thumb, the wind turbine should be placed a minimum of 30' above any obstacles within 300 feet of the wind turbine. This usually means an 80-100 foot tower height for most residential installations. Shorter towers put the wind turbine in very turbulent air, which reduces power output and can shorten the life of a wind turbine substantially. Be sure to put the wind turbine on the tallest tower you can afford to purchase! Modern wind turbines can be connected directly to the AC power grid or can be used to charge batteries in off-grid homes.
Energy Efficiency:
Energy Efficiency is the key to any renewable energy power system. Without being more energy efficient, solar power systems would have to be larger and more costly. It just makes sense to make your home (and your life) more energy efficient when considering a solar or wind power system. Did you know that every $1 invested in energy efficiency saves more than $4? That's money in the bank! Here are some ideas to make your house more energy efficient:
Install Compact Fluorescent lightbulbs (CFL's) or LED lightbulbs. Lighting accounts for up to 20% of residential energy use!
Unplug TV's, Computers, and Electronics when not in use. Put them on a power strip. Did you know that so-called "phantom loads" can account for up to 15% of residential electrical use?
Look for the Energy Star label when shopping for new appliances and electronics. Energy Star products save 20-30% compared to conventional models.
Add insulation to your existing home. In Alaska, heating accounts for more than 50% of residential energy use. By adding extra insulation and sealing around doors and windows, you can make your home warmer and easier to heat.
Finally, have an energy rater conduct a thorough evaluation of your home. A blower door test will identify any problem areas and show you where air is leaking in! AHFC currently has programs available to help homeowners with weatherization.
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