How Efficient Are Solar Batteries?

by | Aug 26, 2022

Solar and battery packages
Providing renewable power at any time of day, solar batteries are a convenient storage option for households with solar panels. Solar storage is becoming increasingly desirable, whether you’re looking for standalone batteries or solar and battery packages.

With high solar panel battery costs, renewable storage can be a significant investment, even bundled with panels. Naturally, you want to get as much as possible from your solar storage. With this blog, we’re diving into solar battery efficiency, helping you to build and get the most from your home solar setup.

What is solar efficiency?

When it comes to solar batteries, ‘efficiency’ refers to how much energy is successfully stored and converted to usable electricity. The higher the efficiency of a solar battery, the more effective it can be.

According to consumer advocacy group Choice, lithium-ion batteries should be more than 90% efficient. Since lithium-ion is the most common type of solar battery, this efficiency benchmark is an important thing to keep in mind when looking for solar storage.

But what does this mean in real terms? Using the above lithium-ion example, if the battery stores 10kW of energy, 9kW could be converted into available electricity. One kilowatt or 10% of the total is lost in the conversion.

The efficiency of battery types

Solar battery efficiency isn’t standard across the board, with each storage option operating within a different efficiency range. This is determined by the characteristics of each solar battery. The three most common residential batteries are

  • Lead-acid: The most affordable solar battery also happens to have the lowest efficiency of the three. Depending on the brand/model, lead-acid batteries can have an efficiency from 60% to 80%.
  • Lithium-ion: The most popular solar battery for grid-connected homes, lithium-ion batteries generally operate within 80-90% efficiency.
  • Flow: The newest type of solar battery to be available for residences, flow batteries provide around 85% efficiency. This efficiency is complemented by the ability of a flow battery to be completely discharged without losing capacity.
  • We’ve mentioned what ‘efficiency’ means in the context of solar batteries but we can go a little further. Solar batteries, like most components of a solar setup, are interconnected systems with numerous factors affecting performance.

    Because of this, let’s briefly shift the focus to depth of discharge and how it can affect efficiency.

    Depth of Discharge (DoD)

    While efficiency measures the conversion of energy to usable electricity, DoD refers to the amount of energy able to be discharged without increasing degradation. Most batteries need to maintain a portion of their charge in order to avoid damage. Solar storage and solar panels will naturally experience degradation over their lifetime which can have a flow-on effect on efficiency. Lowered capacity reduces the ability of a battery to properly output electricity in line with its efficiency rating.

    Solar efficiency vs cost

    While it can potentially reduce the cost of your electricity bills in the long run, solar batteries can initially be quite expensive. While there are numerous factors affecting solar panel battery cost, efficiency and depth of discharge can be crucial factors.

    Lead acid batteries are the most tried-and-tested storage solution, using the same technology as the battery powering your car. They have lower efficiency but are also more affordable overall. On the other side of the spectrum, flow batteries are a relatively new technology, pairing a complete depth of discharge with higher efficiency. As a result, your solar panels and battery cost more.

    The cost of lithium-ion batteries rests in the middle of the three, featuring high efficiency and more streamlined manufacturing.

    Solar panels, inverters, and storage are complex networks with numerous variables affecting efficiency and price. To discover whether a solar and battery package would work for your home, book a free assessment with the Solar System team today.

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