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Can Solar Power Be Used At Night?

Domestic solar generated energy comes straight from the sun, via panels and an inverter – and is converted into the electricity to power the appliances, heating and lighting you have around your home.

So it stands to reason, that for the power to flow in your home, the sun must be up, right?

Of course, the panels will work only during daylight – you can configure your array so that it captures morning and evening sun better, but the photovoltaic (PV) cells they’re made from are simply not going to convert usable energy from moonlight.

There is, however, a way to use solar-generated power at night: storage.

In a normal, grid-connected domestic solar system, energy that is generated during the day but that isn’t used, flows via an import-export meter back into the national system. Depending on where you live, you’ll get some sort of cash credit for this supply of clean energy back to the grid – but, realistically, it’s not going to be a huge amount.

Instead, you can choose to capture that energy in one or more batteries and then have some of your solar-generated power in reserve to use at night.

For most New Zealanders investigating whether solar power is right for them, the first hurdle to get past is whether their energy use makes day-time generated power cost-effective. If, for example, you run a business from home, or you are a retired couple, or you use a lot of energy during the day to, say, heat a swimming pool or run washing, heating and cleaning appliances, then capturing energy from the sun is a free and efficient way to run your home – these people are going to maximise their return on their investment and see the system pay for itself quickly.

For working couples or families who aren’t at home during the day, but who use most of their power on heating, lighting and electrical appliances and entertainment systems in the early mornings and evenings, then it can be more difficult to make the numbers add up. The first way to maximise their investment is to make a few changes to the way they use power around the home – setting timers on spas, hot water cylinders, washers, driers etc – and the second is to invest in battery storage.

In recent years the cost of domestic battery storage has fallen dramatically as major players in solar technology – companies such as Tesla and LG – have invested in developing reliable, cost-effective batteries for a mass domestic market. Tesla’s Powerwall and LG’s RESU batteries have driven the most headlines worldwide and Harrisons Energy Solutions has partnered with LG as an authorised NZ distributor to bring their latest second-generation of RESU batteries to New Zealand from March 2017.

There are other manufacturers on the market, but when it comes to storing usable solar energy for a Kiwi household, it’s vital that the battery is made to withstand New Zealand conditions, has the lifespan and reliability to work over a high number of cycles (a cycle is the period in which a battery is powered up during daylight charging, and then releases its energy during the night), is safe both to install and to stay the course in a domestic setting, and is designed to fit right in with New Zealand design styles whether it’s installed indoors or out.

For anyone investigating solar energy there are three key messages when it comes to researching batteries:

  • Make sure your system can support being hooked up to a battery. In simple terms, we’re all going to end up with a battery in our home in the near future. As the up-front price and cost-effectiveness of electric cars, solar systems and batteries continues to fall, the time when it makes sound financial sense for every home to be built with access to free, clean electricity comes ever nearer. At that time, if you’ve already got a solar system up and running, you will need to add on storage, and it’s vital that your inverter is the right type to support a battery. There are plenty of different ways companies get around saying whether or not their solar systems are battery-compatible – rest assured, if you are buying your system from Harrisons, we will make sure it is or that your system can be upgraded.
  • Assess your overall household energy use. Buying a solar system is an investment so you need to ensure you are maximising your returns. This is achieved when you look at how and when you use your electricity, any changes you can make to your home’s energy-efficiency (via insulation, heating or ventilation systems) and any changes you can make to how you use your power. Getting a wide-scale energy audit can help you work out whether batteries are right for you.
  • Why do you really want battery storage? There are those who want to save money on their power bills by having access to cheap, clean, renewable solar-generated electricity – and then there are those who want solar and battery storage for other reasons. Some, for example, are more interested in the environment than their bottom line and so want to lower their reliance on grid-supplied power. Others require a system that can support their consumption by using a back-up battery system even if there is a power outage. And then there are those early adopters who just love the sleek lines, cool tech and cutting-edge innovation that goes into battery storage.

If you’re interested in finding out more about the RESU range of batteries or want advice about what system might suit your home, contact us for a free on-site energy audit on 0800 00 33 54 or via our website.