My earlier blog post talks about Solar Power and Solar Energy and recommends to add Solar Energy to our vocabulary.
But, the revolutionary change that we pride ourselves with – is to specify solar heaters in terms of power KWth instead of in terms of energy – Litres Per Day – LPD. Oxymoron!
LPD – Litres Per Day vs KWth
Solar heaters have been traditionally specified as LPD meaning – Litres Per Day. Why?
The traditional solar heaters have been worldwide used in domestic water heaters. When do we need hot water at home? Mornings. Does the sun shine in the mornings? No. So, essentially, we are collecting sunlight and solar energy that shone yesterday and using it today. In that scenario, it is good to express the capacity as LPD – How many useful Litres of hot water can be generated per day.
LPD essentially represents the energy collected throughout the day.
LPD vs KWth – how to represent the size of solar heaters?
But, when it comes to Solar Process Heating systems, we need to work on generating the high temperature required consistently during the day. That means, we need to have the “power” to heat requisite quantity of water instantly using solar generation.
That is why we specify our collectors in terms of KWth!
Here are other articles that talks about KWth rating of solar heater collectors.
~ Bhoo, CEO, Aspiration Cleantech Ventures