How a solar hot water system works

ByT Rich

How a solar hot water system works

Solar Panels Brisbane is a product that provides hot water from either the sun or electricity.

Solar heat is generated by passing fluid through a series of copper tubes in what is known as a solar collector. The fluid is either water or glycol.

Water passes through the tubes if the unit is known as an open circuit, glycol if the unit is known as a closed circuit.

Once the fluid has passed through the copper tubes within the solar collector it either goes directly into the tank as hot water or travels down to a heat exchanger which exchanges the heat from the glycol into the tank water via a coil of copper known as a heat exchanger.

The Glycol is basically a food grade form of ‘antifreeze’, and a closed circuit solar system is used in situations that the system is susceptible to freezing or hard water (water which has a TDS of 600ppm or more).

The electrical boost works when there is no significant solar gain on a particular day.

In A dux electric boosted solar hot water unit, you have 2 elements 1 at the top and 1 at the bottom of the tank.

The elements work very similar to a kettle.

The top element is on what is known as continuous tariff which as the name states is a continuous power supply, which means that if the water above the element is below the desired temperature it will start to heat that water. (an element doesn’t heat water below its placement). We deliver the solar gain directly beneath the top element at a maximum rate of 80ltr per hour so if no more water than that is being used at any one time the element won’t turn on.

The bottom element is charged at an off-peak tariff meaning that the element only comes on at night (at a cheaper rate than continuous tariff) if the whole cylinder is less than the desired temperature.

On a summers day it would be rare for the elements to be required and during the cooler months you would normally register some solar gain (providing the day is bright enough to cast a shadow). In some cases there may be no solar gain on a given day which would mean the bottom element will heat the whole vessel over night.

The placement of the off-peak tariff within the tank provides us with what is known as boost capacity (ie the volume of water above the placement of the off-peak element) the dux boost capacity is 250ltr for a 250ltr 315ltr for a 315ltr and 400ltr for a 400ltr.

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