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Solar PV vs Solar Hot Water

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Solar PV vs Solar Hot Water: Which Renewable Energy Solution Is Right For Your Home?

If you’re looking to make your home more sustainable, one of the most impactful things you can do is to start generating your own clean, renewable energy. So what are your options? From Solar PV to Micro-Wind, Micro-Hydro and Solar Hot Water – even Tesla Solar Roof Tiles, this article will explore the pros and cons of your renewable energy alternatives.

Solar PV: The Most Popular Way To Generate Electricity At Home

First up, Solar Photovoltaic or Solar PV. With over 45,000 systems installed on homes around NZ, Solar PV is what most people mean when they say ‘Solar’.

Solar Photovoltaic panels use semiconductors to capture photons from sunlight and convert them into energy to power any electrical appliance in your home. From the lights to your hot water cylinder – even charging an electric car.

Solar PV panels generate electricity whenever the sun is up, no matter what the temperature is outside, with production higher on clear bright days than on cloudy days. When combined with a battery, excess energy produced during the day can be stored to use at night or at peak times when power prices are high.

Pros of Solar PV:

Cons of Solar PV:

  • Energy is only produced during daylight hours
  • Requires enough available roof space, or space for a ground-mounted system
  • Performance can be affected by constant shading from large trees or buildings
  • Requires an upfront investment
  • It can be difficult to find a good, specialist installer

As specialist Solar PV installers, we see people choosing PV over alternatives like Solar Hot Water and wind every day. With Solar PV, they can power through power cuts, reduce their energy bills and enjoy peace of mind knowing they’ve reduced their impact on the planet. See what some of our customers have to say about their experience with solar here.

How Does Solar Hot Water Work?

Solar Hot Water systems transfer thermal energy, or heat, from the sun directly to water, which is then stored in your hot water cylinder. They are usually installed on a roof, as either flat panels or evacuated tube panels, which feed directly into your hot water cylinder. Solar Hot Water systems usually require a backup booster system, typically operated by gas or electricity.

Pros of Solar Hot Water:

  • Uses free thermal energy from the sun to reduce your water heating bills only
  • Reduces your carbon footprint, especially if displacing gas or diesel water heating
  • Can supply 50-75% of your annual water heating energy requirements when installed correctly
  • Can be retrofitted or incorporated into a new build
  • A quality system has a long expected lifespan of up to 20 years

Cons of Solar Hot Water:

  • Can only be used to heat water and does not produce electricity to power other appliances
  • Only reduces the carbon footprint associated with water heating
  • Weather dependent and not suited to climates that experience large seasonal temperature fluctuations, like the South Island, as they are prone to freezing in winter and overheating in summer
  • Requires a backup booster system which is usually powered by a fossil fuel such as gas
  • Can be difficult to size correctly
  • Require an upfront investment
  • Requires building consent to install
  • Moving parts may require some ongoing maintenance

Think Solar Group does not install Solar Hot Water systems. If you think this option is right for you, make sure you do your research.

What Other Renewable Energy Options Are There?

What Is Micro Wind Generation?

While most wind generation in NZ comes from large-scale Wind Farms, small-scale Wind Turbines are available. Micro Wind Generation works by using wind to turn the blades of a turbine, producing kinetic energy. This energy is transferred to a generator which converts it into electricity that can be used to power any electrical appliance in your home. How much energy is produced depends on the strength and consistency of the wind and the size of the turbine blades. Studies in NZ have found that you need an average wind speed of at least 6–8 metres per second (m/s) for a small wind turbine to be economically viable.

Pros of Micro Wind generation:

  • Wind is a free, clean and renewable resource
  • Can reduce carbon emissions
  • Can reduce your energy bills
  • Can be retrofitted in the right circumstances

Cons of Micro Wind generation:

  • Requires significant upfront investment – a 2kW turbine is around $20-30K
  • Needs minimum average wind speed of 6–8 m/s and non-turbulent air to operate. Which means a turbine must be installed in a clear area with no obstructions. Guidelines recommend above your home at twice the height of the house, or 10 x the height of your house in distance away. This makes turbines most suited to rural areas and are commonly used on boats.
  • With many moving parts they can attract significant maintenance and low quality turbines have a track record of breaking down
  • Susceptible to damage from storms
  • Can be noisy and often considered unsightly

What Is Micro Hydro Generation?

Micro hydro systems are an option in very specific circumstances. You’ll need a slope with a continuous source of running water such as a stream or river. To generate hydro electricity you install a water turbine in the water course, which is turned by the water flow and transfers energy into a generator, which can be used as electricity to power your home.

Pros of Micro Hydro generation:

  • Can operate 24 hours a day, as long as the water flow is consistent
  • Produces clean, renewable energy that can power any electrical appliance in your home
  • Production is often higher in the winter months when electricity demand is also high
  • Can be designed to reduce the negative effects on surrounding water course and environment
  • Requires an upfront investment

Cons of Micro Hydro generation:

  • Only suitable in very specific site conditions
  • Difficult to increase scale as needs grow
  • Requires significant infrastructure and diversion of a water course
  • Can disturb plant and fish life in the water and surrounding areas
  • Requires a building consent and potentially a resource consent
  • Can be subject to damage during storms or periods of very high rainfall
  • Generation can be affected seasonally and in occasionally unpredictable ways (i.e during a drought)
  • Requires regular maintenance and cleaning to remove sticks and debris

When Will Tesla Solar Roof Tiles Be Available In NZ?

As Tesla Certified Installers, we’re often asked about the Tesla Solar Roof Tile. As the name suggests these are glass or steel roofing tiles that have solar photovoltaic cells integrated into each one. They are designed to be your roofing material and solar panels in one, and are used in place of roofing tiles that you see more commonly in the US and the UK. Tesla Solar Roof tiles are only suitable for new builds, as it can’t be retrofitted. Just like Tesla’s Powerwall battery storage products, the Tesla Solar Roof tiles are beautifully designed and very slick.

Unfortunately, we’ll be waiting a long while yet for Tesla Roof Tiles to be available anywhere outside of the US, let alone in NZ. The concept is still being tested and refined in California, and there are lots of hurdles for Tesla to jump through before we see them taking over roofs around the world.

Solar PV, Solar Hot Water or Micro Wind and Hydro: Which Option Is Right For You?

While micro wind and hydro will work for specific sites, almost every home is suitable for Solar. If you’re only interested in reducing your hot water heating bill, then Solar Hot Water might be worth investigating, but when it comes to generating clean, renewable energy for your home or business, Solar PV stands head and shoulders above Solar Hot Water. Solar PV will power any electrical machine in your home, from hot water to your car, to offer an excellent return on your investment – both financially and environmentally. With Banks offering cheap finance and studies showing it is the cheapest power source available in NZ right now, there’s never been a better time to invest in Solar PV.

Find out how Solar PV stacks up for your home. Get a free quote from your local Think Solar specialist here.

 

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