(6) The amount of hot water supplied by solar depends on various factors. If you have a 3.6kW element and 3.6kW surplus solar for a few hours each day, and you don’t send much solar power back to the grid, it’s reasonable to expect that about 80 percent of your hot water will come from solar. However, it’s important to keep in mind that there will still be days when solar energy is not sufficient due to rainy weather.
(7) The lifespan of resistive hot water tanks can vary. While some plumbers may claim they can last for 20+ years, newer tanks may not be as durable. As a conservative estimate, I default to 15 years. The online calculator takes this into account by factoring in a percentage of the hot water system’s cost. For instance, if you assume the system will last 20 years, the calculator will only add half of the upfront price.
Heat Pump Calculations:
Heat pumps consume significantly less energy compared to electric element tanks, approximately only a quarter. This calculation is based on your bill data.
(8) The given price is an estimate obtained over the phone for replacing an electric element with an iStore Heat Pump.
(9) A heat pump draws around 1kW of power, whereas an electric element requires 2.4kW or 3.6kW. Consequently, a heat pump is more likely to be powered by surplus solar energy.
The iStore Heat Pump doesn’t require a Catch Relay or diverter and comes with a built-in timer. Although it cannot be switched on and off as frequently as a basic element, its low power consumption of around 1000 watts enables it to align with your excess solar curve most of the time.
(10) While the iStore Heat Pump has a 5-year warranty, conversations with experienced installers suggest it can last for at least ten years. Karl Jenson claims it can last up to 15,000 run hours, although this information is not substantiated by any iStore documents. Just like the calculations for electric elements, if you assume the heat pump will last ten years, the calculations reflect 100 percent of the hot water system’s cost. Assuming a lifespan of 15 years, the calculations will account for 66 percent of the cost.
Determining whether a heat pump is a better option than a traditional electric element tank involves considering numerous variables. It is especially favorable to choose a heat pump if you are paying higher electricity rates, use a moderate amount of hot water, if electric element tanks have shorter lifespans, and if the cost of heat pumps is comparable to old-school tanks and a Catch Relay. Additionally, if a heat pump can last for 10+ years as claimed by Karl, it further supports their economic viability.