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Solar Power 101 - Everything You Need To Know!

Updated: Jul 5, 2023


Wellington Builders | Design & Architecture Services | Eco-Friendly Design | High Performing Home | Structural Insulated Panels | Energy-Efficient Home

Exterior of house in the evening light

Workers installing solar panels

We're sure you've all heard of solar panels (well, 'solar photovoltaic panels', to be precise). For many years, these sleek, shiny black panels have been adorning the rooftops and lawns of energy-conscious consumers and those who have chosen to live off the beaten track. Solar panels have become more mainstream in recent years as our collective awareness and passion for clean, renewable energy increases. By harnessing the sun's power - THE most abundant renewable resource on the planet - the demand for coal and other less green energy is reduced. Aside from the many planet-saving pros, installing PV panels also equals great electrical bill savings and can significantly increase the capital value of your property. (Woohoo! Sign me up!) ENERGY SAVINGS - A CLOSER LOOK: The standard New Zealand home uses around 8,000 kWh per year (20 kWh per day). Using solar panels on a high-performing home can save you about 1,000 – 2,000 kWh per year.

If you choose to run 100% of your energy through PV, then the 6,000 - 7,000 kWh per year saved, would cost $0! Although the initial cost of investing in these panels can be pricey, the long-term energy savings really add up! (Especially if you live in an area of New Zealand where the per kWh price is high and/or is notoriously unreliable, with power cuts/surges and the like). It's also sometimes cheaper in more remote areas, to install panels and be completely off the grid because it costs more to get the power to a building site than it does to install a full off-the-grid PV system.


You may be wondering whether we get enough sunshine where you live in New Zealand. The short answer is yes! Auckland, Wellington, and Christchurch all receive over 2,000 hours of sunshine each year. The rest of our country (except perhaps, for the far South and West Coast) also receives enough sunshine hours for solar panels to perform well. Panels are so efficient these days that they still operate on overcast days and one of our past clients even generates a small amount of electricity on a clear sky night!


The size/number of panels required for your home depends on the percentage of electricity you want to offset from the grid. Many people choose a size that will eliminate their power bills completely, but others go for a size that will halve their bills.

Grid-connected solar panels, without batteries, may save you around 30% of your grid electricity costs. A 5 kW PV array needs about 40 square metres of roof space and generates approximately 6,000-7,000 kWh/year. Higher grid saving percentages usually require a battery to shift to solar energy into the evening and morning peak periods.


For grid-connected houses, batteries allow the design of an 'annual energy balanced' home – but there is usually still excess energy in summer and a deficit in winter (to be drawn from the grid).

A 5 kW system with batteries costs around $23,000; however, smaller 'battery ready' inverter systems are also available. These are cheaper and can be upgraded in the future. Bear in mind that more solar panels can always be added later as demand or budget grows.


For our clients who prefer to be completely off-grid, we would install a 5 kW system to supply electricity and water heating needs for an energy-efficient house. A bigger battery and/or a backup generator may be needed to ensure power is available through the worst winters. Every house is assessed on its own merits as the size of the system depends on many things.


PV panels are manufactured from rigid polycrystalline and are fixed to a structure on the roof (depending on the roof angle) or mounted on tilted frames. Panels can be installed on most types of roofing including Butynol, metal, rubber and clay/concrete tile. We can also supply ground-mounted panels.

If you're concerned about sustainability, the main components of PV panels are tempered glass and aluminium (and a bit of silicon) – so yes, they are recyclable.


In terms of maintenance, you can pretty much install and leave them! Wash them once a year with soapy water and a soft brush, and that's it!


To work out which PV system would suit your new home, it's best to speak to your architect to estimate how much power would be generated per year. This information can then be input into EECA's solar power calculator to help you establish how much value you would get from installing PV panels on your new home. You can check this tool out here: Solar Tool

Keep your eyes posted for our next blog, and remember, if you have any questions about high-performing homes, please get in touch by clicking here: Contact Us

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