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What Size Solar Hot Water System Do I Need?

Solar Hot water on roof

A solar hot water system is significantly cheaper to run than an electric or gas hot water heater. In fact, you can cut your energy bills in half! And because it’s not reliant on fossil fuels to power it, it’s better for the environment, too.

As long as you have a suitable location to install solar panels on your roof, you can reap the savings on your power bill. But how do you know what size solar system you need to ensure you never run out of hot water? Read our handy guide below to help you pick the best capacity solar hot water system for your home.

What are the different types of solar hot water systems?

Solar hot water systems convert the sun’s energy into hot water for your home. There are two types of solar hot water systems. Both require solar panels, or collectors, to be installed on the home’s roof. A closed-couple system has a horizontal storage tank mounted on the roof, while pumped systems use a storage tank installed at ground level, just like a regular hot water system.

  • In a closed-couple system, the water can be heated directly as it rises through the panels and into the storage tank or by using an anti-freeze passed through a heat exchanger coil within the cylinder. You can read more about open-circuit and closed-circuit solar hot water systems here.
  • A pumped system requires a small amount of electricity to pump water from the cylinder to the panels for heating and back.

Read our article on the ‘thermosiphon’ effect to learn more about the types of solar hot water systems and panels.

What is a solar hot water booster?

Everhot solar gas boosted hot water heater

When the solar panels cannot get enough sunlight to heat the water, a gas or electric booster ensures they work efficiently in any climate at any time of the year.

  • You can install an instantaneous or continuous flow gas hot water system to ‘boost’ your solar-heated hot water on cloudy days. Once a gas booster detects the water temperature has dropped, it automatically ignites to deliver hot water to your tap.
  • An electric booster needs to be switched on, normally at the meter box, and as water leaves the storage tank, it passes through the booster. You can leave the switch on during the winter months, as when the water reaches the right temperature, it automatically switches off.

Can a solar hot water system be installed on my roof?

As we’ve discussed, you don’t necessarily need to have a storage tank installed on your roof with a pumped or split system. But you will need a north-facing location on your roof that receives a good amount of sunlight for the installation of solar panels, or ‘collectors’.

Panels should slope at an angle of between 15° and 45°. A standard roof pitch is around 20°. However, even if you have a flat roof, solar panels can be mounted on a frame to elevate them.

Is solar hot water system maintenance complicated?

Solar panels, or collectors, should be cleaned at least once a year for maximum efficiency. A professional clean and service should occur about once every five years to ensure continued optimum performance. A professional maintenance person can check that the plumbing and pipes are in good order and that the collectors aren’t shaded, cracked, or scratched.

Is the cost of a solar hot water system worth the savings?

When you’re considering investing in a new solar hot water system, sit down with your calculator and work out how much your current system costs to run. Although the initial outlay for a solar hot water system is more compared to electric hot water, a solar system will often pay for itself after just a few years.

As governments work to encourage households to take up renewable energy solutions, financial incentives have followed. You can read more about government rebates to help you install solar hot water here.

How to assess your hot water consumption

To calculate your hot water requirements to determine the number of solar panels and tank size you will need, consider your household size, including how many bathrooms and water outlets you have and how many appliances, such as a washing machine or dishwasher, use hot water. You also need to think about what time of day you use the most hot water.

You can read more about how to measure your home water consumption in our article on picking the best-sized hot water system for your home.

What size solar hot water system is best for a small family?

A household of 1–2 people will need about 2 square metres of solar panels, also known as collectors. A storage tank with a capacity of 160–200 should suffice as long as you don’t suddenly increase your hot water demand by taking more showers than usual or using the dishwasher more frequently.

At Same Day Hot Water Service, the Rheem 52H300 solar hot water heater is a popular unit for small houses. It has a 300 L capacity in a roof-mounted storage tank and is ideal for cool climates. It comes with complete frost protection and can be installed with either gas or electric boost.


Rheem Solar Hiline

What capacity solar system is best for a medium to large household?

A home with 3–5 people will require 2–4 square metres of solar collector area and a tank with a capacity of 300–350 L to allow for days with less sunlight.

The Rinnai 330 L stainless steel close-coupled hot water system is a tough and attractive choice for medium to large families. Its stainless steel tanks are made in Australia, and it is an attractive addition to your property with a range of Colorbond colours available.


When it comes to hot water, we’re in our Element

Using solar energy for hot water is a great way to reduce your energy consumption at home. You’ll see savings on your energy bills and, with the right size system, have access to reliable hot water all year round in any climate.

If you’re looking to buy a new solar hot water system or replace an old one, the experts at Same Day Hot Water Service can help you choose the best system to meet your household demand. We offer a price on supply and delivery or supply and installation. Give us a call today on 1300 721 996.

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