How solar water heating works
Collectors on the roof gather heat from the sun and pass it to the water in a cylinder. Rheem's Premier Loline is a closed-loop, or indirect, system: the collectors heat a separate loop, which then heats the stored water. Rinnai's coiled mains pressure cylinders are built to work with solar and other closed-loop heat sources.
Every Rheem solar water heater comes with a gas or electric boost, so there's still hot water when it's cloudy. For other cylinder types, start at our hot water cylinders page.
What makes a home suit solar
- A roof area facing north, where Rheem says collectors catch the most sunlight.
- No shade from trees or buildings falling across that area.
- A place for the cylinder, and a sensible route for pipes between it and the roof.
- A roof in good enough shape to carry collectors for years.
- Power or gas nearby for the boost.
What a plumber will do
A plumber will check which way the roof faces and what shades it, where the cylinder can go, and how the pipes will run between the two. The boost needs an electrician or an authorised gasfitter to connect it.
On an existing solar setup that has stopped heating well, a plumber can look at the collectors, the circulation, the valves and the boost, and tell you which part has let you down.
Consent, and claims to ignore
Replacing a water heater is exempt from consent under clause 38 only if the replacement is connected to, or incorporates, heat sources that are all controlled, and an authorised person does the work. We couldn't confirm from official guidance how solar is treated under that wording, so have your plumber or the council confirm it for your job.
Sales talk about solar can run ahead of the facts. Sunshine doesn't make hot water cost nothing: there's the equipment, the installation and the boost. We don't repeat savings percentages, which are makers' claims. We couldn't confirm any current national or council scheme that pays for solar hot water, and a bank's 'green' loan is a bank product, not government help.
Things you can do
You can
- Check which way your roof faces and what shades it through the day.
- Watch the controller or display and note any error lights.
- Keep the manuals and warranty papers together.
- Tell the tradie if the boost seems to run all the time.
Leave to an authorised tradie
- Work on the roof, collectors and roof pipework.
- The cylinder, valves and any pump.
- Wiring the boost (an electrician) or the gas boost (an authorised gasfitter).
- Any temperature setting.
Red flags in a solar sales pitch
- Promises that your hot water will cost nothing.
- Savings percentages with nothing behind them.
- A 'government scheme' that can't be named or checked.
- An installer who won't show a current practising licence.
- A quote that doesn't mention the boost or the cylinder.
What we would do
Start with the roof. If it doesn't face roughly north or it sits in shade, solar may not suit, and a heat pump is worth comparing. If it does suit, ask a solar hot water installer to size the cylinder and boost for your household and list every part of the job in the quote.