• Climate hub
  • 22 Nov 2021
  • 6 min read

Six questions to ask before you get home solar

By Joanna Jefferies

Solar panels on roof
Solar panels on roof

Key things to consider with solar panels

Switching to solar panels is a great way to reduce your greenhouse gas emissions, but there’s some key things to consider before you do.

As more homeowners look to reduce their carbon footprintsolar panels are increasing in popularity. In the past year alone, installations have increased 15 per cent and at the end of February there were 31,000 solar power installations across New Zealand.

The number and type of photovoltaic (PV) products on the market are expanding and the cost of having them installed is reducing, which means now more than ever before, solar panels are seriously worth considering for your home.

To help you understand whether to integrate solar into your home, here are six important questions you need to answer before making the switch.

Is my home suitable for solar?

Solar panels are better suited to some situations than others and assessing your property for its suitability is a great place to start. If you use power during the day, have electric hot water, and your roof is in good condition and is north facing, then your home is probably a good candidate for solar power.

This is because PV panels generate energy during sunlight hours and the energy needs to be used as it’s generated. So, if you spend time during the day at home, have an air conditioning system or a pool filtration system that is used during the day, solar panels are a great option.

How many solar panels does my home need?

The average New Zealand home will need 15 to 20 solar panels, but the number really depends on:

  • Your household energy needs
  • How much of your roof is available for panels
  • The quality of the panels
  • The kW capacity of your solar panel system.

Solar power system for home

How much solar would it take to power a house?

The kW rating describes the maximum amount of energy the system can generate at its peak output (most domestic dwellings operate with a maximum output of 5kW). A 5kW system typically requires 15 to 20 panels, depending on their quality.

When assessing how many panels you need, consider that a refrigerator requires two solar panels alone to power it, a spa pool needs 11 and an electric car needs 10. So, if you’re planning on installing home charging or a spa pool down the track, take this into account when you decide on the number of panels you need.

What are the 4 types of solar panels?

As solar energy has increased in popularity the number of options available has increased too. There are four main types of solar panels, and each has its pros and cons.

  • Monocrystalline panels are a common solar energy receptor and each PV cell is made from a single silicon crystal. They have high efficiency, so if your roof space is limited they are a good option. However, while they are efficient, they are also more expensive than other panel types.
  • Polycrystalline panels are more cost-effective than monocrystalline panels because the manufacturing process of melding the silicon fragments used to make them is less expensive. However, they are generally less efficient and tend not to last as long as monocrystalline panels.
  • Thin film panels are the most cost-effective solar panel option but are large in size and have the least longevity of all of the types of solar panels due to lower quality materiality.
  • CPV panels (or concentrated PV) use lenses or curved mirrors to concentrate the light on to small solar cells within the panels. This system has the advantage of being scalable for large roof surfaces (often used for commercial buildings), but it can be expensive.

The type of panel you choose to have installed will depend on the roof space you have available, your budget, how far ahead you want to futureproof and what sized system you need.

Related article: How does solar power work?

Grid tied or off-grid?

Solar provides two options for you, to go off the grid or stay connected to the national grid. When your solar panels are not producing energy and you need back up power, you can draw energy from the grid. When you have excess energy, you can sell it back to your energy provider.

Grid tied solar system

To reduce the cost of your solar panel system you can have a two-way meter installed and export your unused electricity to the grid – this is called being grid-tied. Genesis’ HomeGen offers grid-tied customers 12 cents per kWh for exported power, and this can be used to offset the total cost of electricity for your home. The cost of installing the meter is $127.

Off grid solar system

If you want to store your own electricity rather than sell it to the grid, or if you want to go off-grid completely, you will need to purchase a battery to store the power you’ve generated, to use when the sun isn’t out. However, while the cost of batteries has reduced in recent years, the cost is still high (between $7,000 to $20,000 plus installation) and for most households, batteries still don’t represent enough value for money across the lifespan of a solar panel system.

I've had solar for 10 years... was it worth it?

Get help with the cost of solar panels

Recently the Government announced a $28 million fund for trialling the installation of renewable energy sources for public and Māori housing, which is in line with its commitment to being net carbon zero by 2050. It’s a step in the right direction, but unfortunately, there still isn’t a subsidy available for solar panels for homeowners.

With the uptake of electric vehicles and home charging docks becoming more common, it’s predicted that by 2050 New Zealand will require 60% more electricity. In line with this, we’re likely to see more support for solar panels in homes in the future.

However, for those not willing to wait, banks are often open to extending mortgage lending, and at around three per cent interest, it isn’t a bad option for homeowners wanting to make the most of solar panel technology now.

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