Energy vs. power

This short series is to help build some foundational knowledge that will help you understand the building blocks of Solar.


Energy is the capacity to do work.  Measurements for energy include calories, BTUs, Joules, and Watt-Hours.  We would use the term energy when discussing how much capacity you have in your battery bank.  If you are on grid you will get a utility bill from the power company and that will normally provide you with the number of kWh or Kilowatt-Hours you used last month.  A Kilowatt is 100 watts and a watt hour is one watt being used for one hour.


Power is the rate of consuming or producing energy.  Watt is the unit of measure we use do discuss power.  A watt is defined as amps multiplied by volts.  A solar panel rated for 100 watts can produce 100 watts ofpower at any given time under perfect conditions.  If it produced those 100 watts for 1 hour it would store 100 watt hours of energy. Understanding that a watt is always equal to one volt multiplied by one amp will be very important as we continue this series.  


Two considerations when sizing solar systems are how many watt-hours of storage do you have(ENERGY) and how much power can the system deliver at any moment(POWER)