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Living with Off-Grid Solar Power
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My Personal Experience All of my personal power needs are supplied by an off-grid Solar Electric Power System that I personally specified, designed and installed. Living with an off-grid system, I have gained a unique perspective as to the trade-offs, limitations and benefits of such a system. Also, my home's water system (deep well with submersible pump) is off-grid. Getting this system to work optimally in this Pacific Northwest climate has been a real learning experience. Appliances: Energy efficient appliances are worth every extra penny you spend on them. There is at least a 5:1 ratio of money spent to generating and storing energy versus the cost of not having to use that energy in the first place. After having lived with one for several years now, I find I really love my propane refrigerator. Unlike electric compressor refrigeration, the ammonia-absorption cycle refrigerators are absolutely silent. No more whirrs, clicks and rumbles when I am trying to quietly read a book, or concentrate on a piece of software. True, one will most likely have to give up certain 'features' such as automatic defrost, icemakers, cold water in the door, etc. However, the lack of automatic defrost means that your vegetables wil stay fresh much longer since the interior temperature and humidity are much more constant. Batteries: Batteries are a necessary evil. Large, heavy, expensive and requiring periodic maintenance. High quality flooded lead-acid batteries are by far the most cost-effective. Properly cared for they will last a long time (8-20 years depending on model and use regimen). You will be best off to select batteries that are as large as possible consistent with your energy storage requirements. Multiple parallel strings of batteries should be avoided insofar as possible. Also, you will really appreciate having fewer covers to open when it is time for that peiodic watering of the batteries. Charge Controllers: An essential component in your solar electric power system is the charge controller. This is the piece of electronics which controls how your Solar panels charge and maintain your battery bank. It is best to stick with a simple unit with a long history of reliable operation. Meters and digital readouts on your charge control are fun to watch. However, the charge control can only tell you what the charge controller is doing. From a standpoint of total system monitoring, you really need to know what is going on with the batteries. For this reason, all but the most simple installations will include a system monitoring unit which will largely duplicate the functions of the charge controls metering functions. Save your money. Solar panel wattage ratings are derived in a somewhat artificial manner, designed to make the panel look as good as possible. In general, your charge controller cannot operate the panel in that same manner when actually connected to a battery pack. The difference is about 20% - that is, your '100 Watt' panel will only deliver about 80 Watts into your battery pack. In an attempt to recapture these 'lost watts' the Maximum Power Point Tracking (MPPT) charge controller technology was developed. These units will do what they claim to do, but there are a few unspoken assumptions. First, you will ony see significant power gains when your panels are in pretty much full sunlight, and, second, your battery pack is significantly discharged. The improvement under the more common winter conditions is minimal. Indeed, with overcast skies and a lightly discharged battery pack the MPPT controllers can actually put LESS power into your batteries than a more conventional PWM (Pulse-Width-Modulated) charge controller. MPPT controllers cost a LOT more than PWM controllers. Under most conditions they are not, in my experience, a cost effective choice. Books: Reading books requires only enogh energy to provide light. That is a LOT less than the television! After many years of hectic city living, I am finally whittling down that list of 'Books I Want to Read Someday.'
Thank You, and best regards;
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