Solar battery storage price comparison and savings calculation

The benefit of installing solar batteries


How much do solar batteries cost

The biggest obstacle to businesses installing battery storage in conjunction with solar panels, is upfront cost. The good news is that this cost is rapidly reducing.With large and powerful Lithium Ion batteries becoming exceedingly popular in the automotive industry, energy storage was bound to follow suit. According to Bloomberg, Since 2010, the cost of lithium ion batteries has dropped by 85%. At the same time, global manufacturing of lithium-ion batteries close to tripled since 2014.In dollar terms: basic Lithium-ion battery pricing has gone from $1,706 per kilowatt hour in 2010 to $259/kWh in 2018. By 2024, battery costs could be as low as $147/kWh.For commercial energy storage, this pricing for a completely installed three phase battery pack translates to around the $600/kWh mark.Here is an example to put into perspective: the Tesla model S has a battery capacity of 85kWh, weighing over 500KG. To install an equivalent capacity grid-connect unit for your business, would cost around $50,000.

The best solar battery storage solutions

In today's energy environment, there are a host of experimental and promising battery technologies. In general, however - there are only four main battery technologies:
  • Lithium-ion(Li-ion)
  • Nickel Cadmium(Ni-Cd)
  • Nickel-Metal Hydride(Ni-MH)
  • Lead-Acid
Of these four types, Lithium-ion technology is by far the most common for energy storage.The reason these are offered for grid-connect solar systems are due to the following advantages:
  • high energy density
  • little or no memory effect
  • Good charge retention when not used
  • Best performance to weight ratio
  • Safe for most applications
In the commercial space, the two major players in Australia are the Tesla Powerpack 2 and Pylontech:

Tesla Powerpack 2 vs Pylontech

Tesla is as much a marvel of marketing as engineering, with the famous bet to install the worlds largest 100MW solar battery in 100 days in South Australia. How does the slick design and marketing of the Tesla Powerpack compare with the Chinese offering from Pylontech?The Tesla powerpack 2 are modular units, restricted to a capacity of 210kWh per module. This can be expanded simply by adding additional models. In contrast, the Pylontech can be ordered in increments of 30kWh, making the design more flexible, especially for smaller installations.This aside, the Tesla Powerpack excels in several key areas:
  • Depth of discharge is 100% vs the 80% of the Pylontech
  • Tesla Powerpack contains an integrated cooling system, ensuring heat-stress is eliminated
  • The Powerpack contains a fully integrated inverter, whereas the Pylontech inverter is distinctly separate
This is a rapidly developing space, and competition is set to be fierce. Elon Musk himself estimates the commercial Powerpack will account for 80% of total energy storage sales.

Cost per warranted watt when installing solar batteries

While Tesla currently only provides pricing for their powerpack series on a project-specific basis, the pricing in the US is around the $AUD 600/kWh mark.Pricing for Pylontech is more readily available, and the $600/kWh mark is recommended as a rule of thumb.

How much can I save by installing battery with existing solar system?

This largely depends on energy profile. The way energy is used determines whether batteries are worthwhile for your business.Battery storage saves money for your business in four major ways:
Storing Excess Solar Power
The major downfall with solar energy is that it only generates power when the sun is up. This problem is solved through batteries, which save additional power for use later. For this to work, your solar system must have enough excess capacity to charge a battery.
Reducing Peak Demand Charges
Peak demand charges are based on the maximum power drawn by a business across a billing cycle (monthly or quarterly). Even if this maximum power is only required for a short time, your business will be charged accordingly. Batteries will discharge their stored energy during such periods - greatly reducing the drawn from the grid.
Store Off-Peak Power
Off peak rates (11pm - 7am) are significantly cheaper than during usual business hours. If your business is closed at night, your battery can charge itself to be used during the expensive daylight hours. This allows batteries to save money even without a solar installation at all!
Selling Power to Grid
Currently, retailers are offering feed-in tariffs of $0.12 as a minimum. Your battery can discharge this power into the grid for a credit against your power bill. Future virtual power plant (VPP) schemes will pay battery owners a premium to sell excess power to their retailers at times of high demand.

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Energy savings
with solar storage
Saving per annum
with solar storage*
Total saving est.*
$1.8 million