How Hot Water Cylinders Work – and why Sol•Flare works so well
Find Out More About your Hot Water Cylinder and OneEnergy.nz's Solution
How Hot Water Cylinders Work
All hot water cylinders take in cold water at the bottom of the cylinder, and heat the cold water using a heating element also located at the bottom of the cylinder. The heated water rises to the top, and the hot water exits from the top of the cylinder to the household.
When someone showers and cold water enters the cylinder, the element switches on immediately, and because showers typically happen in the morning and evening, the cylinder reheats at the worst possible time: when power is most expensive and when there is no sunlight available.
Why Traditional Hot Water Cylinders Use So Much Power
A standard hot water cylinder uses a simple 3,000-watt heating element that can only operate at full power.
• It will run for 3–5 hours a day to keep the tank hot.
• It’s usually the biggest power-hungry appliance in your house.
• And the tech hasn’t changed: today’s elements work exactly the same as they did in the 1950s, often consuming 30–50% of a home’s daily electricity use.
How Sol•Flare changes that
The heart of Sol•Flare is its ability to shift your element from a simple on/off device into a variable-power heating system utilising all of the sun’s energy.
Instead of waiting for a full 3kW of power, your cylinder can now heat using whatever the sun provides - whether that’s 200W at dawn to 2,700W in full sun.
Because the power is supplied direct from the panels, there are no inverter losses, and every watt of solar generated goes straight into heating water. This eliminates daytime mains draw and dramatically increases solar self-consumption.
The result is a hot water system that reacts to actual conditions, not just a mechanical thermostat.
Turning Your Cylinder Into a Thermal Battery
With the thermostat turned up (around 70°C or higher, depending on your cylinder’s maximum operating temperature), Sol•Flare can now store excess solar production as additional heat.
This stored thermal energy carries into the evening and early morning, when hot water use is highest.
By using your cylinder as a thermal battery, the system captures and holds more of the solar energy that would otherwise be lost or exported, improving your household economics.
For more detail on Sol•Flare’s benefits: https://www.oneenergy.nz/hot-water-for-homes