Solar Power Battery Storage - An Introduction

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Solar Power Battery Storage - An Introduction

Solar power battery storage is revolutionizing they way people use and consume solar power. It offers numerous benefits and solutions for maximizing the efficiency and utilisation of solar energy.

The average household typically consumes electricity during the morning and evening hours when solar power generation is not at its peak. This mismatch in consumption and generation patterns (as seen in the graph below) can be addressed with battery storage, allowing homeowners to make the most of their solar power system.

In New Zealand, solar-powered battery storage systems, also known as solar battery banks, are gaining popularity due to falling prices and technological advancements. In fact, approximately one-third of all new solar installations in the country now include batteries.

Lithium-type batteries are the most common technology used for solar storage. Tesla Powerwall is one of the big names that is leading the charge in the solar battery marketplace.

How Solar Batteries Work

Prioritised for maximum efficiency, solar power is sent to where it is needed most. 

How Solar Power Is Stored In Batteries - GIF

  1. Solar power is sent to any appliance that is switched on.
  2. Excess solar power charges the battery.
  3. Solar power is drawn from the battery at nighttime or when additional power is required.
  4. If needed, any additional power will be sourced from the grid.

Why Are Solar Batteries Useful?

Solar batteries are highly recommended when surplus solar power would otherwise be exported to the grid during peak solar production hours. Solar batteries function by taking excess solar electricity (shown in the yellow bell shaped curve) and storing the electricity in batteries. By storing this excess electricity, users can consume power whenever they like, typically during non-sunny hours like evenings or cloudy days.

Why Solar Batteries Are Needed - Bell Shaped Curve

Solar batteries offer several advantages, including:

  1. Maximizing self-consumption: Store excess solar power instead of selling it to the grid.
  2. Power backup during blackouts: Most batteries can power appliances even during power outages (make sure you specify a battery type that works during power outages when requesting quotes).
  3. Utilising renewable energy: Increase the use of green energy, reducing reliance on peaker power plants that are often fossil fuel-based.
  4. Reducing electricity bills: By using stored solar energy, households can decrease their reliance on grid power and reduce electricity costs.

What Is The Price Of Solar Batteries?

The price range for solar batteries is roughly $6,000 to $20,000 NZD.  Typically the more storage a battery has, the more it will cost.  Other factors that affect the price are the capabilities of the battery, quality of the battery, chemistry used and how long it’s expected to last.

Here’s a quick rundown of  some of the products available on the market along with their estimated price:

Battery Model Usable Capacity Battery Chemistry Power Output Approximate Price
Solax Triple Power 6.3 kWh Lithium Nickel Manganese Cobalt Oxide 3 kW $6,500 (uninstalled)
Huawei Luna2000 10 KWH 10 kWh Lithium Iron Phosphate 5 kW $10,500 (uninstalled)
BYD Premium HVM 13.8 kWh Lithium-Ion Phosphate 3.6 kW $17,000 (installed)
Tesla Powerwall 2 13.5 kWh Lithium Nickel Manganese Cobalt Oxide 7kW peak / 5kW continuous $18,000 (installed)

Please note these prices are rough estimates.  For accurate quotes, fill in our quote request form here for 3 free quotes.  

View and compare more battery storage products available in New Zealand here.

Solar Battery Storage For Black Outs

Solar batteries can be set to power appliances when there is a blackout, or during a power outage. Note: not all batteries offer this feature, be sure to ask when making a purchase.

Here's how solar batteries work in a power outage:

  1. Storm detection: Many solar batteries receive storm warnings from meteorological data. When a storm warning is received, the battery will proactively prepare for a power outage by storing as much power from solar generation and the grid.
  2. Power outage detection: When a power outage occurs, the solar battery system detects the loss of grid power.
  3. Automatic switch to backup mode: In response to the power outage, the solar battery system switches from grid-tied mode to backup mode, disconnecting from the grid to protect utility workers and prevent the solar energy from flowing back into the grid.
  4. Power supply from the battery: Once in backup mode, the solar battery system provides stored energy from the batteries to power essential appliances and circuits in your home or business.
  5. Continuous power supply: The solar battery system continues to supply power during the outage, allowing you to keep critical loads running, such as lights, refrigerators, medical equipment, or other essential devices depending on the capacity of the battery system.
  6. Recharge after the outage: Once grid power is restored, the solar battery system switches back to charging mode, replenishing the battery storage from the grid and solar panels.

Will Solar Power Still Be Exported To The Grid If Solar Batteries Are Installed?

Because such low rates are paid for exported solar power (roughly 8-12 cents per kWh), sending power to the grid is the last priority for the solar power system. 

Solar power will be sent to (1) appliances first (if they are switched on), and then to the batteries (2).  Only if there is additional excess solar power will the system export solar power to the grid.

Where Solar Power Is Directed When Solar Batteries Are Added

Why Install Solar Storage?

A solar battery allows homes and businesses to store excess solar electricity and use it when it’s needed most.  Here’s a shortlist of why this is a good thing:

  • Store excess solar power instead of selling it to the grid for a low price.
  • Ability to keep the lights on and the fridge running during a blackout.
  • Use more green energy; 20% of New Zealand’s electricity is created from burning fossil fuels.  With solar battery storage, you can use more renewable energy.
  • Reduce electricity bills or get close to eliminating them.  Solar batteries will help the household use more of the solar energy created, which means less demand for grid power.

Read more about the benefits of solar battery storage here?

Should You Install Solar Batteries In Your Home?

For Power Security - Yes!  If you are sick of power outages, or the idea of not having power for a day makes you nervous, then absolutely, solar batteries can be sure to provide a home or business with power during a blackout.
For Financial Return - Maybe not quite yet.  A solar battery is likely to reduce a solar power systems return on investment and lengthen the payback period.  
To Reduce Power Bills - Yes!  A battery will reduce those pesky power bills on top of the savings already made with a solar power system.

Lithium-ion Battery Technology

Battery storage technology; it's a race to develop the ultimate solar battery storage system. Lithium-ion battery technologies are the most common battery on the market. Lithium-ion batteries are smaller, lighter and store more energy than traditional lead-acid batteries.

Lithium-ion batteries are found in mobile phones, laptops and electric vehicles - increased demand for these products has prioritised economies of scale for lithium-ion, with the cost dropping roughly 20% each year.

The reason lithium-ion is used for solar batteries includes:

  1. Energy Density: Lithium-ion batteries have a high energy density, meaning they can store a significant amount of energy in a relatively compact size.
  2. Efficiency: Lithium-ion batteries have high charge and discharge efficiency, so they can effectively convert and utilise stored energy.
  3. Long Cycle Life: Lithium-ion batteries have a long cycle life, meaning they can undergo many charge-discharge cycles before experiencing a significant decline in performance. Therefore they will last a long time.
  4. Fast Charging: Lithium-ion batteries can be charged at a faster rate compared to other battery technologies. This allows solar battery systems to capture and store the energy generated from solar panels quickly.
  5. Self-Discharge Rate: Lithium-ion batteries have a low self-discharge rate, meaning they retain their stored energy for longer periods when not in use.
  6. Safety: Lithium-ion batteries have undergone significant advancements in safety features and management systems. Modern lithium-ion batteries for solar applications are designed with safeguards to prevent overcharging, overheating, and other potential safety risks, ensuring safe and reliable operation.

Retrofitting Solar Storage Batteries

Fear not, savvy and smart early adopters of solar technology. Existing grid-connected solar power systems can be retrofitted to include a solar battery bank. The best battery configuration for retrofits is often an AC-coupled battery.

Having a battery ready solar power system is an excellent option if a user is considering adding solar storage at a later date.

Read our blog articles about solar battery storage here>

Read about grid-scale batteries in New Zealand here>

Get 3 free quotes for solar + battery storage here>