Why knowing your Watts from your Watt-hours is important

Posted Thursday 26th of June 2014 at 16:34


Being able to correctly size up an off-grid renewable power system depends on knowing your energy requirements and this is where watts (W) and watt-hours (Wh) come in.

In the same way that power and energy are often used inter-changeably so are watts and watt-hours - in fact they are quite different. Power is the rate at which energy is generated or consumed and is measured in units Watts. Energy on the other hand is the work done over a unit of time and is measured in watt-hours - Wh.

Here's a useful analogy that explains the difference between the two. Speed is a rate of how fast you drive at an instant in time while distance is the length that you drive over a period of time. If you drive at a constant rate of 60 miles per hour for one hour then you will have travelled 60 miles.

When describing how much electricity you need to generate from a renewable energy system then it is best to talk in watt-hours over a 24 hour period. So in the case of a CCTV camera drawing a constant 36W this translates to a daily consumption of 1kWh allowing for 10% system inefficiences.

To address this power need we would propose one of our horizontal wind generators the LE-300 24V system with 2 x 100W solar PV fed into a 225Ah deep cycle battery (larger capacities can be used if required) as illustrated here. This would generate the electricity needed to run the cameras 24/7.

cctv off-grid power system

If you are looking to power some equipment in a remote location and there's no readily available grid connection then we can help you size up the right off-grid power system to give you peace of mind that it will be running all day every day no matter the weather!<