Battery storage has had us talking in big numbers lately. We were used to conventional power stations having ratings of x hundred megawatts. This had been sufficient for us, because they provide continuous power over long periods. However solar storage batteries run for shorter periods after sunset. Hence, it has become necessary for us to understand the difference between megawatts and megawatt hours.
What are Megawatts and Megawatt Hours?
Watts are basic units for measuring power. Megawatts are one million watts. Mega was once a word meaning the ultimate or biggest as in mega rich. We have larger numbers now, but the custom is still with us.
As a general rule of thumb, ten average-size automobile engines produce one megawatt combined.
However, a megawatt hour is something different. It is equal to 1,000 kilowatts of electricity running through a system for exactly one hour. This is similar to electricity consumed by 320 average homes during 60 minutes. Therefore, megawatts and megawatt hours are different units of measurement.
Kilowatts and Kilowatt Hours in Home Energy Storage
Let us bring this down to practical terms of home energy storage. Kilowatts are power, in other words the amount of energy released in an instantaneous discharge.
A home solar system produces fewer kilowatts on cloudy mornings, compared to sunny afternoons. We use batteries to smooth this out.
Kilowatt-hours, by comparison are the volume of electricity delivered, or consumed over time. Therefore if a solar system delivers one kilowatt of electricity continuously throughout one hour, it will have delivered one-kilowatt hour in total.
How to Right Size a Home Solar Battery Pack
A home solar battery set should be able to deliver x kilowatts of electricity for a specified period. Consult your utility for your average monthly kilowatt-hour consumption. From this, you can calculate your average daily use and your total kilowatt capacity requirement according to your circumstances.
Remember to allow time to recharge the batteries when your outage ends, and add a provision for unusual circumstances and seasonal events too.
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Preview Image: Balancing Supply and Demand