Solar Water Heating Wellington

Solar Water Heating Wellington

Solar water heating is one of the most efficient ways to heat water in your home. Solar panels can be installed based on your rooftoop and house size.

Solar water heating is a method of using sunlight to heat water with the help of solar thermal collectors. This heated water is then stored for use in insulated hot water tanks. Solar water heaters are efficient but sometimes may require external energy boosters if sunlight is not enough.
Wellington is an ideal place for solar water heating. If you are an eco-friendly person or you want to spend less on electricity or you have very little power available then solar water heating is the way to go.

There are two kinds of solar collectors, namely, flat plate and evacuated tubes.

There are two types of installations pumped and thermosyphon. Pumped is the most popular in especially when retrofitting an existing house.

What competes with solar water heaters for efficiency and cost? Heat pump water heater. It has a similar efficiency at a lower cost. Contact us for more info.

solar array in Newtown Wellington
A large solar array we installed in Newtown Wellington

Pumped vs Thermosyphon

From a plumbing perspective, there are pumped and thermosyphon (or unpumped). Thermosyphon installations the tank is installed on the roof top with the solar panels. Often owners don’t want a tank on their roof due to the weight of the tank on the roof. With a pumped installation the tank is usually inside the house or it can be in the roof space.

Pumped system consists of a circulation pump along with a controller installed to the geyser to regulate water to the collector and then water returns once it is heated.

Most solar water heaters in New Zealand are pumped. If a building is designed for solar water heater, the tank and collector can be installed on the top. Ensure you are not likely to get freezing conditions as thermosyphon systems suffer if the pipes freeze.

Flat Plate vs Evacuated Tube
Flat plate and evacuated tube are types of solar collectors. Tube collectors have the advantage of having a vacuum, which makes it harder to get condensation and mildew on the inside the glass, which is what the flat plate collectors suffer from. Freezing is also an issue for flat plate water-filled collectors. Freezing is overcome with a glycol filled closed-loop system or a controller that has a feature to eliminate the problem by starting the pump briefly to get the water moving slightly to stop it from freezing or a drain back system. Evacuated tubes usually generate slightly more energy than flat plate collectors but are more prone to damage from hailstones and other solid objects.

EECA Solar Installer

EECA or Energy Efficiency and Conservation Authority (Te Tari Tiaki Pūngao) is a government agency which supports renewable energy and helps in improving energy efficiency in New Zealand.

EECA believes in efficient transportation, productive business, energy efficient homes, and more.

We are an EECA approved solar installer based in Wellington. We offer solar panel installation services in Wellington and suburbs such as Miramar, Upper Hutt, Lower Hutt, Whitby, Khandallah, Porirua, and more.

Solar Water Heating Wellington


We offer repairs, maintenance, and replace solar collectors, solar pumps, controllers, diagnose faults, replace insulation and repair frost damage and leaks. We repair flashings and improve energy efficiency. We cover all areas in Wellington for solar water heating including Island Bay, Johnsonville, Karori, Khandallah, Lower Hutt, Lyall Bay, Miramar, Porirua, Pukerua Bay, Seatoun, Tawa and Upper Hutt.

Solar Water Heating Frequently Asked Questions

Are Evacuated Tubes better than Flat Plate?

Tubes are slightly more efficient, particularly U tube types. Flat plate is less likely to be damaged by hail or stones. Evacuated tubes are more efficient in winter and later in the afternoon. Flat plates are usually better at midday.

Can I use my existing tank?

Tank size depends on the number of people consuming the supplied hot water.  1 person = 135 litre, 2 people = 180 litre, 3 people = 225 litre, 4 people = 250 litre, 6 people = 300 litre.  If your tank has that much capacity, that will be fine. If not, a smaller collector will be used and the installation will not meet your daily needs. With solar water heating, the daily hot water requirement needs to be collected between sunrise and sunset.

Some tanks have heating limitations eg max 70’C so the solar collector controller is set to no more than that.  Specialist solar tanks often have higher limits.

Does the pump need much power?

Pump usually needs around 15 to 35 watts when it is running. The pump runs when the sun has heated the collector.

Are we approved EECA installers?

Yes, Southern Plumbing is EECA approved installer.

What happens if the power is turned off?

The pump stops working. The controller will restart when the power is turned on.

There are some solar installations where the collector is below the tank where convection can occur between the collector and the tank. So no power is required.

Can I have solar water heating when my roof faces east or west?

Not for best results. Sometimes we can put them on the northwest side.

Can I have solar water heating if my collector area is half shaded?

No, it is difficult to collect enough hot water to repay the installation.

What maintenance is needed in solar water heating?

Wash the collector once per year, check the pipe insulation, check the pump is operating, change the glycol if your system has it, not many do. Check plumbing for leaks, if the system is closed loop check it still has pressure on the pressure gauge. Lastly, check the roof fixings.

Who Can Install a Solar Water Heater Plumbing?

A licensed Master Plumber can install solar water heaters. We are a certified plumbing company in Wellington, you can contact us for installing solar water heaters in your premises.

What Happens in the Winter?

Solar water heaters don’t get as much sun as needed, but will heat the water from cold to about 30-40 degrees depending on whether the collector has been correctly sized. The collector will heat water even when it has been raining all day.

solar hot water heating image of evacuated tubes installation in Wellington

Solar panel installation is a great way to save on your energy bills. If you are looking to install new solar panels in your home or business, contact us today. Contact us for solar panel installation, repair and maintenance services in Wellington. We are available for emergency services on 24 hours basis.