• What are my energy needs?       Your electricity needs will vary greatly depending on application.  Completely off-grid systems will obviously need more power than systems used to supplement on-grid systems.  The total load should be determined through the examination of every appliance that will be used.  The total energy need should include a small amount more than the total load since the system itself uses some energy. 

• How do I determine my total load?       All AC and DC appliances must be examined to determine the power rating (watts).  Then you must determine the amount of time that these appliances will be operating (hours).  The power rating is then multiplied by the time to determine the watt-hour requirement.    The total system loss of power is generally equivalent to 35% of the power generated.  This amount must be added to the total system need.  The daily power requirement is the total solar power requirement.

       1.  AC Requirements:

                   Power Rating (W) x Operation Time (h) = Watt-hours (Wh)

       2.  DC Requirements:

                   Power Rating (W) x Operation Time (h) = Watt-hours (Wh)

       3.  Battery, Inverter, Controller, Photovoltaic Power Requirements:

                   35% of total from lines 1 and 2.

       4.  Daily Power Requirement:

                   The sum of lines 1, 2 and 3.

• How can I reduce my total load?       Efficient appliances are integral components of efficient power solutions.  Using fluorescent bulbs in place of traditional incandescent bulbs can save hundreds of thousands of watt-hours every year!  Some refrigerators, freezers, lights and other appliances are specifically designed to compliment these efficient systems.  Lower power consumption means that more power can be diverted to other needs or it can be sold back to the power companies.
• How do I determine which photovoltaic modules meet my needs?       Once the total solar power requirement has been determined, you must examine the various models to determine which modules will be the most cost effective.  The module's power rating must be multiplied by the area factor to determine the watt-hours produced per module.  The amount of solar energy that can harvested per cell depends on the location of the user, since an equatorial system would generate more power than an arctic system.