Solar Battery Essentials

6 questions that can save you literally 1000’s of dollars (and much disappointment as well)!

 

  1.  What do I want to achieve?

    complete-load-profile-with-ac-electric-heat-electric-water-heater-and-led-lighting

    Typical load profile

    • Reduce my power bills further (if you already have solar panels)
    • Never have to pay a power bill again
    • Take advantage of energy trading (e.g. “Reposit”)
    • Security against black-outs
    • All of the above

  2. What Do I know about my power consumption pattern?

    • Do you know how much power you use during the day, during the night, in the mornings and at evening peak time?
    • Do you have a smart meter that can provide this information?
    • Does your existing inverter and its dashboard or web interface provide this data?

  3. I want to protect my home against blackouts – how many hours or days of grid independence do I need?

    • Just for a few hours (e.g. during a storm)?
    • A couple of days?
    • More?
    • Are you prepared to reduce the energy you consume during battery operation (“Critical load circuit”)?
    • Do you need to protect critical It equipment from brown-outs and shutdown?

  4. Do I know a local battery installer I can trust?

    • Adding batteries to a new or existing PV Solar system and getting it right is a bit more complex than just solar alone. We consider it crucial to have a local installer with experience in that field, someone who can attend at short notice if things go wrong or need fine-tuning.

  5. Are there any bulk buys happening in your area at present?

    • Some community groups, local Councils and community energy retailers conduct bulk buys that help greatly taking the hazzle out of buying a good quality system at affordable cost.

  6. Does your energy retailer assist with solar and/or solar battery installations?

    1. Some retailers offer free energy assessment services or are affiliated with local installers. This can be a good thing if the offer is financially attractive and the components are top quality.
    2. Be wary of retailers that want to sell you a one-size-fits-all system without considering / assessing your individual needs.

Read here about the author’s personal experience with a 8kW solar and 10kWh battery system, installed in 2017.

Technologies for Home Owners and Small / Medium businesses

The range of currently available battery storage solutions is vast and getting larger by the month. GOODBYE GRID has developed a comprehensive calculator to assist in making the right technology and capacity choices. Read the latest feature comparison of available storage battery systems, their features, specs, warranties and cost: https://www.solarquotes.com.au/battery-storage/comparison-table/ , comparing all currently in Australia available battery storage systems. In short, these technologies are competing for making you grid-independent:

  • LEAD ACID GEL (VRLA) and AGM batteries. Both are well established, maintenance free, recyclable and relatively low cost. On the downside, they are heavy, use toxic materials and depth-of-discharge (D.o.D.) is low if you want to get a long cycle life out of them. They also reduce in usable capacity when the ambient temperature goes up.
  • HYBRID LEAD ACID A term that includes a range of  improved lead acid batteries to get better depth-of-discharge and cycle life. The most common brand in Australia is ‘Ecoult’.
  • LITHIUM ION There are several sub technologies under this header, and new ones show up all the time. LiFePo4 is one of the most common, LiS (Sulphur) and LMC are other Lithium based technologies. These batteries have a cycle life of up to 10,000 cycles at 80% D.oD. Caution is required, though, because manufacturers are moving towards WARRANTING not the number of cycles, but kWh charged and discharged over life. WARRANTED life is typically 10 years or less on a daily charge / discharge cycle. Lithium batteries need to be operated on dedicated controllers to avoid the risk of overheating and fires. Cost have been higher than Lead Acid, but are coming down quickly. Typical brands include TESLA, SAMSUNG, SONNEN, ENPHASE, AMPETUS, AU OPTRONICS and LG Chem.
  • SODIUM ION Also called Aqueous Hybrid Ion (AHI) batteries. They work with a salt solution and are probably the least toxic of all batteries – 100% recycable as well. Size and weight is larger/higher than Lithium Ion. AQUION is the only brand currently on offer in Australia. The key features are the affordability (on par with good Lead Acid batteries) and the ability to discharge 100%. 3000 cycles at 100% D.oD. are warranted, 5-6000+ cycles at 80% D.o.D. can be realistically expected.
  • FLOW batteries, such as Zinc Bromide technologies. The most common brand in Australia is ‘REDFLOW’. These batteries deal very well with hot ambient temperatures, have a long cycle life with good maintenance and can left discharged for a long time without suffering damage. On the downside, the batteries are bulky, heavy and have moving parts like pumps. Good for stationery applications where high temperatures are an issue.
  • NEW TECHNOLOGIES Reports about new technologies can be read almost every week. Zinc-Air, currently being used for tiny batteries in hearing aids, is one of many technologies to watch. Another one to watch is Aluminium Ion or Aluminium Air.

Stand-alone systems require a battery inverter (e.g. SMA’s ‘Sunny Island’, ‘Zeus’). Some battery systems come integrated with batteries, a combined grid/battery inverter and even solar panels. AGL offers a complete turnkey system based on the AU Optronics battery. The  TESLA Powerwall 2 features a 13.8kWh battery with all electronics included for the price of approx. A$ 12,750. We are convinced that other companies will match or better this price before long. Grid-Hybrid systems use the Grid as backup. In the past, most solar inverters (batteries or not) would shut down if the grid suffered an outage. This is designed to avoid powering the grid form the back end if there is a power failure. Click here for an easy-to-understand introduction to Hybrid Solar. Modern inverters have a UPS (Uninterruptable Power Supply) feature, drawing power from the solar panels or the batteries if the grid goes down. As long as the charges for staying connected to the grid are reasonable, using the Grid as a backup for a run of rainy days is fine.

But what if the utilities keep ramping up the fixed costs? Read on how get ahead regardless! Hybrid solar 1

 

Without the Grid, the choices are a combination of the following 3 components:

  • Over-sizing your solar power system to create a charge current to your batteries even on overcast days. Typically, depending on where you live and how important energy security is for you, allow for a PV capacity of 2-4 times the capacity that covers your needs on a sunny day.
  • Have a backup generator.  Diesel generators are best suited because of better fuel efficiency. You may consider sharing a gen-set with your neighbours!
  • Allow for sufficient days of autonomy when sizing your battery bank. ‘Days of autonomy’ mean how many days the battery can provide you with power IF and WHEN the sun is not shining and your solar system sits idle.

 

 

Fortunately, GOODBYE GRID have developed a proprietary calculator that takes the guesswork out of designing your independent energy supply – Contact us and we will guide you towards the most efficient and cost-effective choices. Our fees for assessing your needs and giving you independent technology advice are very small compared to what you can save in getting it right: with the right technology, the right supplier of technology and sufficient, but not excessive solar and battery capacity. In some cases, we will conduct energy monitoring to make sure we understand your load profile correctly.
Our fees start from $300.