Sizing your system.
What we know.
By rule of thumb, a regular household needs 20 litres of hot water per day for general use, plus 50 litres per person a day.
So a 3-person household will use roughly 170 litres per day of hot water.
Under our calculations, generally 1 kWh is needed for every 20 litres of hot water.
So our 3-person household uses 8.5 kWh a day, on average, for hot water.
So…
A 3 kW array (about 10 panels) will more than suffice for heating water, for approximately 9 months of the year, in Auckland.
Simple to install with no plumbing required.
Our inverters connect straight from you solar panels to your hot water cylinder element so you don’t need to change the plumbing!
“Overclocking” your system.
We match your inverter to your hot water element size, but the Hot PV™ inverters can take more panels than their rating, without needing to be up-sized. This is called “overclocking”.
We use this capability to improve the performance of your array in spring, autumn and winter. For example, adding another 2 panels will improve your spring and autumn water heating energy by about 2kWh each day.
And for the 3-person household example, in winter an additional 4 or 5 panels would bring the family close to 100% winter solar water heating capability - on good winter sun days.
So you should only need to boost when there is a prolonged lack of sun!
