The two most important important factors when considering the size of your system are sunlight intensity or insolation values in your area and the daily power consumption of your electrical needs.
Insolation is measured in equivalent full sun hours. One hour of maximum sunlight received by a module equals one equivalent full sun hour. Even though the sun may be above the horizon, for example, 14 hours a day, the site may only receive six hours of equivalent full sun. Reflection and angle of incidence both work to cut down the effective energy. When, for example, the sun is directly overhead the light is passing through the leash amount of atmosphere. Early or late in the day, however, the sunlight is passing through much more of the atmosphere due to its position in the sky.
Because of these factors, the mos t productive hours of sunlight are from 9 a.m. to 3 p.m. around solar noon. Before and after these hours, power productions will be at much lower levels.
After determining the amount of solar radiation available, determining the size of the load is next. The unit of measure for sizing is either watt-hours or amp-hours. We normally use watt-hours because it applies to both AC and DC circuits.
In the end, whether the load is a pump system, an RV or a remote homesite, a calculation for average daily watt-hours consumed is needed. With that figure in hand, the number of modules and batteries needed can be determined.
The table below is an analysis of energy usage for a representative small home. Using this chart will help you to understand where your power is going and may give you ideas for how to reduce your loads.
Incorrectly assessing loads can be frustrating and expensive. Underestimating loads can lead to system inadequacies and overestimating loads can lead to excess capacity. Either of these problems can be avoided easily by a careful assessment of loads. It is important that you become comfortable and knowledgeable with the day to day operation and maintenance requirements of your equipment, and that you rely upon yourself to ask us questions if there is something you do not fully understand.
Your country solar electric system size will depend on the size of your home and family. First, consider propane appliances for as much of the energy load as possible including the range, o ven, auxiliary water heater, heating/cooling system, refrigerator and dryer. Solar electricity can easily provide for what's left; the TV/VCR, lights, kitchen appliances, microwave, washing machine, computer, fans, power tools, pumps, etc. Add a solar water heating system for up to 80 percent of your domestic water heating needs.
Table 1: country solar electric example
Your city solar electric system size should approximate your annual electricity use only, since most electric utility companies are not obligated to purchase your excess solar electricity. Sizing your system to meet your average rather than your peak monthly electricity use means that during off peak months (ex: April and October) you'll be sending you surplus solar electricity to the grid (utility company power lines) and spinning your meter backwards, while during peak air conditioning months (ex: from May through September), you'll be supplementing your solar electric system with power from the grid.
Table 2: city solar electric example
All our solar systems are AC power so you can run all your standard appliances and tools. Even the 450 peak watt system is substantial (ex: 6 modules x 75 watts = 450 peak watts). Folks all over the country are comfortably living "remote" full time on our 450 peak watt system while running all the appliances and entertainment they desire. And our "ultra reliable" Passive Domestic Water Heating Systems (no pumps, controls or sensors) start at only $1,595.00 for the 14 sq. ft, 20 gallon all copper ECS system. Wind Systems are also available from Mr Solar.
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