The Basics of Solar Energy and Home Battery Storage
If you’re new to the solar world, then you’ve come to the right place. We will walk you through four different solar scenarios, starting with the Grid-Tie System, and then moving onto the Hybrid Solar System, AC Coupled Solution, and the Hybrid Three-Phase System. Along the way, you will learn the basics of how solar energy is captured, converted and stored.
In 2017, solar energy and home battery storage vastly grew in popularity among Australian residents. According to the Clean Energy Council, “A total of 28,000 battery systems had been installed across Australia by the end of 2017.” (Clean Energy Council, 2018)
The awareness of renewables continued to make its mark through 2018-19, and the industry accelerated with the help of government subsidy schemes, increased environmental awareness and the overall affordability. “As of December 2018, more than two million rooftop solar power systems had been installed across Australia.” (Australian Government, 2019)
Now, in mid-2019 a newly published report by Australian Energy Market Operator and Energy Networks Australia suggests that household solar and batteries can deliver value for all electricity customers. “The world is looking at Australia as the leader in installing rooftop solar and batteries to incentivise and integrate the customers to benefit all.” Says, AEMO Managing Director and Chief Executive Officer, Audrey Zibelman. (Australian Energy Market Operator and Energy Networks Australia, 2019)
Recent studies and public action proves that solar with battery storage is and will be our future. There is no doubt that our grid will change, consequently decreasing the cost of electricity and altering the effects of climate change.
The grandfather of solar, the Grid-Tie system is a solar inverter which started to gain popularity in Australia in the 1970s. So, how does it work?
Sunlight is converted to energy by the solar panels. Solar panels are made of smaller cells called photovoltaic cells, and these ‘photovoltaic’ cells can convert sunlight into energy. This energy is in the form of (DC). Unfortunately, this isn’t very useful in most household applications as everything in your house runs off alternating current (AC). So, DC needs to be ‘inverted’ to AC before it can be used which is done by the grid-tie inverter. Once the inverter changes the electricity from DC to AC, the energy it produces will make its way to your electrical network/appliances. (Your lights, washing machine, fridge, air-conditioning, microwave, television, etc.)
When your solar panels start generating more energy than your household appliances require, you can sell it back to the grid and earn a credit on your energy account. To do this, you need to organise an agreement with your energy retailer and gain permission to export the energy. Your energy retailer will set the rate you sell the electricity and to be clear, you typically don’t trade it for the price you brought it. Although these figures can vary between each distributor and state, the average Australian purchases electricity for approximately 15-35 cents per kWh. Comparatively, most households will only receive 6-18 cents for each kWh generated back to the grid. To export your generated energy, you will need a suitable smart meter installed if you don’t already have one.
No sun equals no energy!
There have been considerable advances within the solar industry, and you’ll find that the Hybrid Inverters and Hybrid all-in-one solutions have started to dominate the market. A traditional grid-tie set up only allows you to benefit from your solar power system during the day. This means you still need to buy electricity when the sun is not shining, which is generally more expensive.
Additionally, your traditional grid-tie inverter is unable to provide you with backup power in the event of a power outage as there is no battery storage attached.
Hybrid Solar System
The hybrid inverter connects directly to your solar panels (PV system), your home (electrical network), the electricity grid and your home battery storage (if installed). Just like the grid-tie system, the solar panels convert sunlight into energy through the ‘photovoltaic process.’ The power will go from the panels to the inverter via DC than from the inverter to your household via AC.
If your solar panels are producing excess electricity, a hybrid system will charge your available batteries storing the excess energy for later use, rather than selling it back to the grid you’re able to use this energy when you get home at night. Then, once your batteries are fully charged the excess power can then be sold back to the grid.
You can store and monitor your electricity.
We consume most of our power in the morning when we’re getting ready for work, and in the afternoon when we get home at the end of the day. However, solar panels generate most of their energy in the middle of the day, which is known as the ‘solar window’. The Hybrid Solar Inverter with home battery storage ensures you aren’t wasting those much-needed sun rays generated during the day, storing them in your battery for later use.
The ‘Solar Window’
With some systems, you have the power to decide when and where you use your energy. With the Redback Smart Hybrid System, you can monitor the amount of electricity your solar panels are producing, the amount being exported back to the grid and your household energy consumption. This recorded data will assist you in managing your electricity use with more efficiency so you’re able to put practices in place to reduce your energy consumption.
The need for electricity to be imported from the grid can be minimised when your Redback Smart Hybrid System is managed well, meaning you can save even more money. For example, you could manually set your pool pump so it would switch on at noon, taking full advantage of the sun and your solar power system.
Assuming noon would be the best time, supported by your solar data via your MYRedback app or Redback Portal and the cost of your electricity.
If you currently can’t afford the hybrid inverter and the home battery storage together, it’s suggested that you invest in the hybrid inverter opposed to a grid-tie traditional setup. That way, if you want to add batteries down the track, you can, the set up will be simple and it will look a lot better. This option could be assisted through a battery scheme in your state.
AC Coupled System: w/ monitoring to third-party grid-tie
If you already have solar panels (PV) on your roof and would like to add battery storage, then a system could be installed in an AC-coupled solution. The system would connect to the same switchboard as the inverter that you already have for your existing solar power system. The Redback system is capable of facilitating this setup; it is just a variation to the wiring.
If your installer was to wire a Redback Smart Hybrid System through an AC-coupled approach, you would still have the advantages illustrated above; however slight inefficiencies can exist. In simple terms, the electricity must jump through a few more hoops to get to the inverter and your household electrical network. The electrical current must change between DC and AC several times so the electricity can travel among the stages. Energy is lost throughout this process, hence why it can be slightly less efficient.
In saying this, the inefficiencies are only slight, with operation levels between 93%-96%. Therefore, this system setup is still viable and ideal for people who already have solar panels installed as it is generally cheaper than a complete refit of a brand-new solar power system. However, please note – you will need to purchase the entire system. You can’t add the battery cabinet as an individual component at this stage.
Hybrid Three-Phase System
The big boys of the solar world. Typically, we would recommend this either for light commercial use or larger homes with around five to six bedrooms. Large air-conditioning systems, electric car chargers, saunas, pool heaters, etc. The Hybrid Three-phase works like the Hybrid Solar System, however, three live wires go out to the grid (three phases) rather than one live wire. This means more power can be pulled from the grid, and more solar energy can be exported to the grid.
Redback can install a meter that reads the amount of electricity importing and exporting. The meter would be strategically placed after the billing metre with the aim to manage all three wires as one. This is called ‘phase netting’ – your single-phase inverter can be used on a three-phase house and compensate for the loads on all three phases using the PV (solar panels) and home battery storage. This practice is put in place to reduce the amount you as the homeowner are spending on electricity.
Australian Energy Market Operator and Energy Networks Australia . (2019). OPEN ENERGY NETWORKS. Australia: AEMO and Energy Networks Australia.
Australian Government. (2019). Solar PV and batteries. Retrieved from Australian Government: Department of the Environment and Energy: https://www.energy.gov.au/households/solar-pv-and-batteries
Clean Energy Council. (2018, May 30). Clean Energy Australia Report. Retrieved from Clean Energy Council: https://www.cleanenergycouncil.org.au/resources/resources-hub/clean-energy-australia-report