Your Guide to PV Solar Water Heating

Are you considering installing a solar water heating system in your New Zealand home or business? This guide, curated by the Green Heat team, is full of everything you need to know about solar water heaters, including how to operate and maintain them.

Solar water heating - Modern way

What is a PV Solar Water Heater?

PV solar water heating uses photovoltaic technology and a unique PTC AC/DC element to heat the water in the hot water cylinder (HWC). This differs from traditional thermal hot water systems where water is cycled from a collector through pipes to the HWC, either making use of a 220V Pump, 12V Pump or natural convection.

The PV solar method of water heating is considered highly efficient and environmentally friendly as it reduces the dependency on traditional sources of energy, such as gas or electricity.

Advantages of Installing a Solar Heating System

There are many advantages to installing a solar water heating system on your New Zealand property. Read about just some of them below.

Energy Efficient

Solar-powered hot water systems can help you save money on your energy bills. Because water is heated using natural resources, these systems can help keep electricity costs down.

Renewal Energy Source

Another advantage of installing a solar water heating system is that they decrease environmental damage. Solar power is a renewable source of energy, meaning you can say goodbye to harmful emissions. This is unlike fossil fuels, which release harmful gasses into the atmosphere once burned. Solar water heating systems can, therefore, help to reduce your carbon footprint.

Maintenance Made Easy

Solar water heaters require maintenance from time to time but not the Green Heat system. PV water heating is completely maintenance-free to maximise your savings on your investment. The PV panels on your roof come with a 25-year guarantee which will give you great piece of mind. Lifespan is over 35 years on most PV panels which is the part of the system most exposed to all the elements.

Easy Installation

Have an existing hot water cylinder? No problem! We can convert any regular HWC into an environmentally friendly PV Solar Water Heater. Plus, no additional plumbing is necessary, making installation quick, easy, and convenient.

No Pumps Necessary

The PV solar water heater doesn’t use a pump to circulate water, meaning you’ll save money on future maintenance and repairs.

Say Goodbye to Damaged Panels

When you install a PV solar water heating system, you can rest easy knowing your panels are safe from damage in frost-prone areas.

Eliminates Overheating With Water Temperature Control

Experiencing harsh weather? PV solar water heaters allow for temperature control, meaning you can eliminate the risk of the system overheating.

Modular System

Going off-grid? A modular PV solar water heater is the option for you. Every Green Heat PV system can be expanded to build an off-grid power system for your home. Plus, because the system doesn’t need to be situated near the panels, we can install it in an area that makes sense for you.

Suitable For All Water Conditions

Hot, cold, or warm, the Green Heat PV solar water heating system is durable enough to withstand all water or weather conditions.

How Do They Work? Breaking Down the Basic Components

When trying to understand how PV solar water heating systems work, it’s best to break them down into their basic parts. Those parts are:

I. Photovoltaic cells and panel

II. Existing Storage tank with upgraded AC/DC dual element

III. MPPT

IV. Controller

Photovoltaic Cells and Panel

Photovoltaic cells, also known as solar cells, capture sunlight and convert it into direct current (DC) electricity. These cells are usually grouped in panels and are oriented facing the sun which in New Zealand, is your Northern roof. The objective of solar panels is to capture the maximum amount of solar radiation. The panels we supply at Green Heat are premium quality and are sold with a 25-year guarantee and an 87% performance guarantee over 30 years.

The Hot Water System and Storage Tank

Once generated, the electricity is channelled to the water heating system. With the Green Heat system, you can utilise your existing hot water cylinder which could be a low-pressure, mains-pressure, solar or wetback cylinder. This warm water is then stored in the tank and ready for use as you need it.

In another sense, your hot water cylinder is used in the same way as a battery to store energy in the form of hot water. Your existing heating element will be removed, and a new marine-grade stainless steel (SS316) with a dual AC/DC heating core will be retrofitted. It is compatible with 99% of hot water cylinders.

MPPT

The Green Heat Maximum Power Point Tracker (MPPT) is a revolutionary device designed to make your solar panels more efficient and maximise their power output. It works by tracking the maximum power point of the solar panel and adjusting the current and voltage to extract the most power from the panel. With the Green Heat MPPT, you can get the most out of your solar installation and enjoy higher yields from your solar energy system.

The Controller

A vital component, the controller helps manage and maintain the precise operation of the whole system. Our intelligent controller is designed to manage your hot water needs to your best advantage from both an energy and economical point of view. It uses professional techniques and the control system is managed by a computer microprocessor.

The controller's primary function is to control the temperature of the hot water cylinder and manage the energy going into the tank.

Additionally, the controller plays a protective role in the system. It will regulate the temperature of the solar to never exceed 75°C from the solar panels and make sure you have sufficient hot water from your normal power source if it's a rainy day.

Types of Solar Water Heaters in New Zealand

There are three main types of solar hot water systems available in NZ. They are:

1. PV Solar Water Heater

These systems use electric PV solar panels with only a wire running down to your hot water cylinder. The solar power is then fed into a special AC/DC element which is installed in your existing hot water cylinder. The PV solar water heater is by far the most reliable and affordable solar system available.

2. Active Solar Water Heaters

These systems use pumps or fans to circulate water through solar panels, which heat the water and then store it in a hot water cylinder. There are limitations to these systems, however, as they can’t be installed on all properties and require lots of plumbing. In addition, since these systems are mechanical, they need regular servicing and often fall subject to wear and tear.

3. Passive Solar Water Heaters

These systems rely on natural convection to circulate water through solar panels, which heat the water and then store it in a hot water cylinder. Installing and maintaining these systems can be expensive, especially because you’ll need to install an HWC on your outside roof.

How to Select the Correct Solar Water Heating System for Your Property

If you’re thinking about installing a solar water heating system on your property, the following considerations may help you narrow down your search.

Climate

The first is the climate. Think about where you live and the kinds of weather you’re likely to experience. If you live in an area with lots of sunlight, then you’ll want a system that captures as much of that heat as possible. However, if you live in a more temperate climate, then you might benefit from choosing a smaller system, as they require less sun to operate.

PV Solar is, however, more efficient than thermal solar systems in winter because it operates using light and not heat.

Hot Water Usage

The next thing to consider is your hot water usage. If you have a large family or use a lot of hot water, then you’ll need a system with a higher capacity. On the other hand, if you only use a small amount of hot water, then you can probably get by with a smaller system. When calculating your water usage, a good rule of thumb is to approximate 50lt of hot water per person per day.

Budget

Finally, you need to think about your budget. Solar water heating systems can range in price from a few thousand dollars to several thousand, so it’s important to find one that fits your needs and budget.

By taking all of these factors into account, you can be sure to select the solar water heating system that’s right for your property.

Strive Towards a Sustainable Future with Green Heat Solar Water Heaters

Using a PV solar water heating system is an excellent way of harnessing natural resources to meet your energy needs. These systems are cost-effective and efficient, promoting a greener and more sustainable environment. Contact our team to get your hands on our solar water heating products today!