Fast Facts

Considering installing solar energy?

Unison has been researching and trialling solar technology for three years now, and we’ve learnt a lot from this work.  The advice we provide is based on what we have learnt, and we want to share this so you can make an informed decision about solar energy (also known as solar photovoltaic, or solar distributed generation).

We’ll also explain how solar energy works, and some of the things you should consider when making the decision to invest.


Solar calculator website image (550x300) 2015
Get a balanced view

While seeing the drop in your power bill sounds very appealing, installing solar energy is a significant investment, and calculating the long-term benefit requires consideration of a number of factors, including how you use electricity, potential changes to electricity pricing for DG connections, and the cost of financing your purchase.  New Zealand is already a very ‘green’ electricity producer, with close to 80% of delivered electricity coming from renewable sources. Before making the commitment to purchase, check out advice from New Zealand-based, independent sources, such as Consumer, and Energywise (EECA)

Read the Concept Consulting report on New Technologies Emissions


The fast facts
Here is a quick overview of the things you should consider when thinking about installing solar energy.

Choosing your system size

The solar energy system you choose should be sized to supply your day-time loads. Installing an 'over-sized' system doesn't mean greater cost savings, as the low electricity buy back rates don’t give a return on the additional cost of installing a larger system.

Installing solar energy

To get the most from your system, the orientation of your roof is important – north facing roofs, or flat roofs with panels angle-mounted on frames give the best yield from solar photovoltaic (PV) panels.

It's important to choose an experienced installer who can advise on the right system, and any promised savings should be carefully checked.

Calculating the benefits

As mentioned, when calculating the financial benefit, there are a number of factors to consider, including the cost of financing your purchase of the equipment, installation costs, buy back rates and your usage patterns and potential. Be wary of relying solely on a solar provider’s online calculator, as they may not incorporate all the factors that should be included, thus over-estimating the financial return on investment.  Unison's solar benefits calculator uses our current DG price category when calculating benefits.

Powering my needs

Solar energy will not supply all your electricity needs, especially during peak demand periods in the winter mornings and evenings, when there is little or no sunshine.

There are energy management tools that can move electricity consumption to coincide with maximum solar output – for example hot water cylinder timer delays, or delayed start options on appliances.

Property Occupancy 

Consider the length of time you expect to be in your home. Solar is a long-term investment which is important to think about in the context of the average amount of time New Zealanders spend in a house - which is six years. This is particularly important when considering a long-term solar lease, which may require you to pay it off if you need to terminate your contract earlier than expected.

Changing electricity costs

The pricing that lines companies in New Zealand can charge is regulated, but the current regulation did not anticipate the introduction of solar energy.  On 1 April 2016, Unison is introducing a new price category for Distributed Generation (DG) customers.   The DG price category is mandatory for all new DG consumers after 1 April 2016 (existing DG customer will remain on their current price category through until 31 March 2019, after which the DG price category will also be mandatory).  As with all pricing categories, the DG price category and charges will be reviewed annually.  Unison's solar benefits calculator uses our current DG price category when calculating benefits.

Battery storage

Battery storage can further optimise the use of solar generation, as well as provide back-up power during an outage, but these are expensive, especially if you want to go off-grid. If you do wish to go off-grid, you will require very large battery capacity, and some back-up alternative generation (either LPG or diesel).


Why do people choose solar?

Nearly 80% of New Zealand’s energy is produced from renewable sources such as hydro and wind, and we do not have a shortage of electricity. So the question is, why do people choose to invest in solar energy systems?

Solar energy is still an ‘emerging’ technology, with around 6,000 homes in New Zealand using a solar energy system in 2015.

In the early years, cost was so prohibitive that for many, it was simply not an economic choice, and so their reasons were more likely to relate to the environment, the desire to be self-sufficient, or to protect themselves from future electricity price increasesThrough our research, we have gained a greater understanding of the extent to which solar achieves these goals, as they relate to New Zealand’s own environment and electricity industry. If these are key motivations for you, be sure to check out our findings.

Saving money on electricity is also an obvious reason and, as technology becomes cheaper and more readily available, perceived cost savings are increasingly becoming one of the major motivations.