Rooftop solar has proved itself to be immensely popular in Queensland, where roughly 27% of all homes have had a system installed, according to the APVI. But more and more Queensland homes and businesses are looking towards energy storage as a way to make better use of their home-generated solar electricity, reduce their reliance on the grid and save money on their electricity bills. What questions should Queensland residents ask themselves if they are considering energy storage for their solar power?
Energy storage in Queensland: Why it’s in demand
The strong feed-in tariff incentives that once drove the solar industry in Queensland have been significantly reduced in recent years, but retail electricity prices remain high, so generating electricity at home is still an attractive prospect for many homes and businesses in the Sunshine State.
The only downside at the moment is that any excess solar power sold into the grid will earn the solar system owner only about 6-8c per kilowatt-hour (kWh) – significantly less than what they would save on their power bills if they ‘self-consumed’ the solar electricity themselves. The upshot of this is that without energy storage, Queensland solar homes must aim to consume as much of the electricity that their panels produce as possible by running appliances during daylight hours. The problem is that peak solar output times do not always match up with typical peak electricity consumption times – which usually take place during the morning and late afternoon.
These circumstances set the stage for energy storage to come to the rescue: If a customer can find an affordable energy storage option, they can not only save money on their power bill by using their solar power when it is worth the most to them (e.g. in the evening) – they can also reduce their reliance on the electricity grid.
In short, energy storage is becoming increasingly attractive for Queensland households because:
- Solar energy system prices are low, making solar power affordable compared to retail grid electricity.
- Retail electricity is expensive – as much as 50c/kWh or higher if you are on a time-of-use (TOU) tariff.
- Solar export rates are low, at around 6c/kWh, so it doesn’t make sense to send your solar into the grid.
- Energy storage costs are coming down quickly.
Do all energy storage systems provide backup power in the event of a blackout?
If you’re interested in energy storage primarily to ensure that you have access to electricity even in the event of a blackout, a system with backup functionality is what you are looking for. But keep in mind that not all energy storage systems have this capability – you’ll have to ask for it and may also have to pay for it.
Considerations and questions about energy storage in Queensland
For those considering a solar + energy storage system for their home or business in Queensland, it’s essential to be well-informed before making a decision. The questions below will help you shape your understanding of how energy storage works, thereby helping you to make the right choice.
Is time-of-use (TOU) metering right for you?
Generally, it is easiest to get the most out of an energy storage system if the household in question switches to a time-of-use (TOU) electricity tariff with their electricity retailer. Under a TOU tariff, peak electricity rates (those which apply for electricity used in late afternoon to early evening) are typically very high, while daytime rates are quite low (especially when compared to a flat-rate tariff). By storing solar electricity during the day and then discharging the batteries later – when electricity is expensive – a home could potentially save significantly more than if they were to remain on a flat-rate tariff. Anyone wondering whether TOU is right for them should consult with their solar installer to see if it makes sense.
Energy storage system sizing: Choose your level of independence
- What degree of energy independence is right for you? Is your ambition to go completely ‘off-grid’, or is your aim simply to reduce your reliance on grid electricity while also reduce your electricity bills? One of the main determinants of your answer to this question may be your budget – if you have no budgetary limits it may make sense to make yourself wholly independent, but if you are budget-conscious a smaller system may make more sense.
- What size solar PV system is right for you? Industry best practice for grid-connected solar arrays is to size the system to meet the daytime electricity demand of the home or business to which it is attached – this is what most installers will recommend. However, it may make sense for you to oversize your system if you’d like to generate all (or most) of your electricity yourself – especially in the relatively lean winter months, when sunlight is less abundant.
Are batteries still too expensive for you? Consider getting a hybrid inverter for your solar system
Hybrid inverters are inverters which can intelligently manage power from multiple inputs – including the grid, solar panels and a battery bank. They cost a bit more than standard inverters but give you the option to easily add batteries in the future.
Evaluating & comparing energy storage system options
- Battery technology type: Lead acid and lithium-ion battery packs are the most common battery types that you will come across, but new technologies such as flow batteries are also coming onto the market.
- Key metrics for energy storage – Cycle life, DoD and storage efficiency: When comparing battery types, be sure to check the spec sheet for cycle life, recommended depth of discharge (DoD), and round-trip storage efficiency of the batteries in question – all of them will play a role in the overall cost of storage for the system.
- Warranty duration: Systems should have warranties between 5-10 years, depending on the type of battery. Check the terms & conditions of the warranty to make sure you do not void it through inappropriate use (such as discharging the battery too deeply too frequently).
Special considerations for retrofitting energy storage to your existing PV system
Many Queensland residents who are interested in energy storage already have a solar system installed. What should you keep in mind if you’re planning on retrofitting an energy storage system to your existing solar array?
- Will you need a new, battery-friendly inverter? Your system’s existing inverter may already be battery-ready – but it depends on the type of energy storage technology that you’re considering. If your system is over 5 years old and due for an inverter replacement, this might be a good time for you to consider installing energy storage – or at the least, a hybrid inverter.
- Are you the recipient of one of Queensland’s generous feed-in tariff rates? If you currently receive 44c/kWh or more for the electricity you export to the grid under a state-mandated feed-in tariff program, it may not be worth your while to install batteries.
- What proportion of your electricity consumption does your existing solar system meet? Depending on when you had your system installed and whether or not you have/had a feed-in tariff, your system may only generate enough power to meet a small portion of your electricity needs – or it may generate more than you actually need. This will dictate the best approach for sizing your battery storage. Speak to your installer about how to retrofit a system to optimise value.
- What energy storage system size would best suit your needs and budget? Do you want to go off-grid at all costs (possibly to spite your utility), or do you view energy storage as an investment akin to solar PV? Your answer to this question will help you determine the optimum system size.
© 2015 Solar Choice Pty Ltd
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