Following the successful Climate Change even organised by KWT at the KSLSC on 27 February 2020, attendees were asked what the further information they would like and what action would they like to consider. One strong theme that emerged was the desire to make a personal contribution by installing residential solar power on either an individual or collective basis. In response, KWT has conducted some research to present basic straightforward information as a starting point.
There are three broad residential solar power options currently available:
Main Solar System Components
There are two types of solar panels:
Polycrystalline panels are slightly less efficient as they have lower silicon purity. So, slightly greater area coverage is required to produce the same power output. However, in Australian conditions the difference is not significant and this should not be a major consideration.
The most important consideration is to buy quality solar panels. Quality brands should last for more than 25 years. Cheap junk panels will last only 3-5 years. Having said that, there are some good quality budget brands. You will probably need advice about panel selection to ensure value for money – check www.solarquotes.com.au for a list of reputable brands.
Inverters convert the DC electricity that the solar panels produce into 240V AC electricity, which is required for everything in your home.
There are two types of inverters:
Micro inverters optimize each panel individually which results in more energy production. They are more effective if panels subject to periodic shading. They are more expensive and will add an average of 20% to the overall installation cost. String inverters are usually sufficient when cost is taken into consideration.
Inverters are the component most likely to fail in a solar power system as they have an average life of 10-15 years. This is because they are functioning full-time. It is more cost-effective to buy a quality item.
RACKING / MOUNTING
These are attached to roof supports and solar panels are mounted on them. Again, there is a wide quality range. Premium mountings may cost $100 per kilowatt of power more when compared to budget products.
The simple answer is fit as many solar panels as your budget, roof size and your distributed network service provider (e.g. Ausgrid) will allow. It makes economic sense to go big. This advice is based on three factors:
If you have single-phase power, the permissible limit will be around 6.5kW. If you have a large rooftop and three-phase power, you can increase this capacity.
The rationale for going big is:
Angle of Panels
There is more flexibility than previously believed about the directions and angles at which panels must be installed to make solar systems efficient. The basic principles are:
Because panels are now cheaper, they can be installed at various angles. For example, you can install both east and west panels to maximize the length of the day. Don’t let the angle of your roof put you off as there are solutions. Even south facing panels produce only 28% less than north facing panels. In most cases, the pitch of your existing roofline will be sufficient. This allows quicker and cheaper installation.
Systems with Batteries
The main reason for installing a battery with your solar system is to go ‘off grid’. There is a strong emotional attraction to the ideal of independently providing for all your energy needs and turning your house into a carbon emission free mini power plant.
There is also the security that everything will keep running, day and night, during a total and prolonged power outage, which have been prevalent on the Central Coast in recent years. Due to climate change these power outages may become even more frequent. However, ironically, it should be noted that many battery systems will not provide backup when the grid goes down. If you really need backup then you must specify this up front, as it is often an extra feature that requires careful design and some rewiring of your switchboard.
Batteries can be retro-fitted to existing solar systems, All grid connected systems installed in Australia are compatible with batteries using a box called an ‘AC coupled battery inverter’. You can purchase these when you buy your batteries, and solar battery installation should be straightforward.
However, batteries are relatively expensive and, if you have limited resources, now is probably not the best time to acquire them. They can be added to a system at a later time. The economics of batteries is discussed in more detail below.
The economics of installing solar power systems
COST OF SOLAR SYSTEMS
The following table sets out the average cost, after rebates are taken into account, of a solar system without batteries. These costs include installation. The cost range reflects the available quality differences.
If you want to use micro inverters, that will add approximately 20% more to the above costs.
COST OF BATTERIES
A battery with 10kHW of storage capacity will currently cost about $12,000. However, there is a general expectation that prices will drop significantly in the next 2-5 years.
There can be additional costs if you need an electricity switchboard upgrade or other electrical work to make your home suitable for solar power, or if the design of your home makes the system installation more difficult.
There is a Federal solar rebate for the installation of solar photo-voltaic systems. It is known as the Small-scale Renewable Energy Scheme(SRES). The rebate is being reduced every year, but is still significant. The rebate varies according to the size of the system. For example, in 2020 in NSW, the rebate is $2,812 for 5kWh and $5,032 for 9kWh.
NSW ended its broad-based rebate scheme in 2016. It is now trialing a limited solar system rebate for very low-income households in specific areas including the Central Coast (see energysaver.nsw.gov.au). It is limited to 3kHw systems and must be installed by specified suppliers. It is not a viable option for most households.
Unlike other States, NSW does not currently have a comprehensive rebate scheme for solar system batteries. However, it is trialing a new interest–free loan scheme called Empowering Homesin limited areas, but not the Central Coast. It should be rolled out more broadly next year. A loan is not as good as a rebate but it is still an incentive.
The fundamental principle of solar power systems is that power is generated while the sun is shining. So for systems without batteries, the rationale is to consume as much of your energy requirements during the day, but you will not be able to consume all the energy you will generate. The unused surplus energy needs to be exported (fed-in) to the grid at a price (a tariff).
It is more profitable for you to consume your self-generated energy than to export it. This is because you are paying energy companies somewhere between 25c and 30c per kHw for the energy they provide, but they will only pay you somewhere 7c and 20c for the energy you export to them.
A change of lifestyle and perspectives may be required to maximize your economic outcome. For example, run washing machines and dishwashers during the day. Power-up all your devices during the day. Run hot water systems during the day, not at overnight off-peak rates. Where possible, set up timers to run appliances if you are not usually at home during the day.
If you want to shop around for energy companies who provide the best feed-in tariff rates, you should assess all price components, including the price they charge for power as well as other fees and charges that may apply. It’s the overall price of the package that counts.
PAYBACK TIME PERIODS
A solar system without a battery will have a payback time in the range of 3 to 8 years. The broad time range is totally dependent on your ability to meet most of your energy needs during the day. However, even if it takes 8 years, this is still a 12-15% return on your investment.
Batteries are a different story. At the moment, the average payback period of a battery is about 15 years and, as most batteries only have a 10-year warranty, you may have to replace it before you have broken even. However, the shining light is that the economics will become more advantageous as prices drop in the future.
If you can afford to purchase a solar power system, then do it. You are crazy not to. It is a secure and attractive investment, one of the few in these difficult times. Even more important than the pure economics, you will be making a personal contribution to the reduction of carbon emissions and the fight against climate change.
Unless you must have a battery right now, wait a couple of years when the price should significantly drop and they become more economically viable. Remember batteries can easily be retro-fitted to existing solar systems. There is the potential to share batteries across households and defray their cost. This involves establishing a local mini-grid. This option will be explained in a future article.