News September 2018
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Our Projects

Residential Grid-Connect Battery Projects

Domestic House Electric with Battery Back up

15 Systems installed with 1500 - 2800 watts Peak Solar


Energy Storage Solution

Solar Battery Benefits

Our storage solution can be integrated with an existing solar grid system or combined with a new solar grid installation.

The benefits of Energy Storage allow you to optimize the use of your green energy either directly from the sun to your house grid or store excess power for use at night or high demand periods.

It ensures you are protected during Black-outs.

Suitable for new or existing solar grid power systems.

Solar Battery Systems

Our system is designed using SMA Flexible Storage components combined with Sonnenschein Smart Home Battery Solution.

System specifications

Solar Battery Dimensions
  • Sonnenschein@home Lithium: 6.8 kWh of Storage
  • SMA Sunny Island Battery Inverter 4.4 Kw
  • SMA Sunny Energy Meter

Additional cost may apply:

  • Switch board upgrades
  • Three phase installations
  • Array and components

Optional: Sunny Home Manager

Utilizing SMA Sunny Home Manager the control center for smart energy management it offers all functions for seamless PV system monitoring, smart energy management and an integrated energy management solution along with an overview of all energy flows in the home allowing you to use your solar power best.

Note: Older SMA inverter without Bluetooth compatibility will need to be replaced.

Alternative: Intelligent Uninterrupted Power Supply

Selectronic Solar Hybrid Solution

Solar Battery Dimensions

Our Solar Hybrid system will give you an uninterrupted power supply meaning you are protected from grid outages. Your system will power on through any interruption to the electricity grid - simple, automatic and undetectable. Your solar power will continue to be used by the household and any excess is sent to the battery for later use. If you experience an extended outage, an optional generator controller can be installed to control an auto-start generator that will only start when the battery is depleted.

Simple, automatic, undetectable.

  • Self consume all solar power
  • Minimise export
  • Minimise grid use during peak electricity times
  • Protection against grid outages
  • Optional backup generator for extended grid outages
  • Recharge batteries from grid or solar panels

Peak lopping

Solar Battery Dimensions

Electricity charges come in many different forms. In commercial applications, it is common for electricity charges to be based on the site’s peak demand. Utilising a battery bank with any SP PRO intelligent inverter allows additional load capacity to come from battery storage rather than the electricity grid. When demand reduces, batteries will be recharged ready for the next peak demand event. Peak demand charges can be significantly reduced with this system.

Grid Support

The same system as used for Peak Lopping can be used to support a grid which has insufficient supply capacity. To add additional capacity to a grid, particularly a rural grid, can be very expensive. Additional capacity is easily supplied by incorporating battery storage and an SP PRO inverter. Whenever the AC load demand is above the grid capacity, additional energy comes from the SP PRO and battery bank.

Solar Battery Dimensions

Myths and the truth in simple words

Battery support systems generally offered on the market in South Australia are small battery bank [ approx. 1.5 kw] with NO back up should a power outage occur in your area.

At Natural Technology Systems, we only offer systems that will provide continuous power during power Outages and allow load shaving/ offset of evening power consumption to reduce power cost when required.

The amount of power available will be determined by the installed battery bank capacity. WE BELIEVE 10 KW of available STORAGE Capacity will run your lights, fridge freezer and associates small electronics including gas water heaters for 6 hours.

The 2 options available are:

LITHIUM-ION battery bank which can be discharged to 80% per discharge and still give 10 years’ life.

Advantages: Good deliver of battery energy due to cycle capability

Disadvantages: Runs at high voltage, each cell needs to be independently monitored, subject to thermal runaway resulting in fire.

GEL battery bank which requires a larger capacity to meet cycle life.

Advantages: Low voltage, proven technology, has track record as been used for 20 years.

Disadvantages: Requires larger storage to match Lithium cycle capability.

NOTE: Should you have the current State Government 42 cent subsidy it is only advisable to add batteries if you are not getting rebate currently. A high capacity of 1.5 to 2 KW systems were originally installed and so a battery bank will be an advantage.


Battery Storage Information

A battery system is used primarily to offset evening electricity consumption and to make use of Time-of-Use (TOU) tariff which is not widely applicable in South Australia which most household use Single-Tariff.

Retrofitting a PV system:

Battery Inverter Requirement: A battery inverter connected to the battery system is necessary to convert DC current to household AC current, which is a separate unit from a Photovoltaic (PV) inverter.

There are 3 options to retrofitting a battery system (to suit 48V battery) over an existing PV inverter:

  • Adding a Battery Inverter.
  • Replacing with Hybrid Inverter (PV inverter + Battery Inverter in single unit).
  • Replacing with Energy Storage System (PV inverter + Battery Inverter + Battery in single unit).

Each bundling restricts the flexibility of the system and generally is less efficient than their specialized counterparts. Modular designs are more flexible in adapting to future changes and making upgrades more viable.

Differences between Low Voltage Battery and High Voltage Battery System

High voltage batteries (350-450V nominal) and low voltage batteries use different types of battery inverter designed to regulate

  • This high voltage is a result of stringing multiple lithium-ion cell stacks to form the battery pack. These cells are used in laptop batteries and as such, we believe it is an economic design factor since laptop battery cells are widely available and as such affordable, but it is not a standard large-capacity battery.
  • As such, these units, we believe are susceptible to string failure (much like Christmas string lights breaking circuit when one fails in series) within an array. This failure is minimized by load shifting through their battery management system, but the overall efficiency would be compromised resulting an eventually degradation in usable battery capacity. (expected 70% of the original usable capacity after 10-year period, their 10-year warranties at least 60% energy retention). Large-capacity low voltage battery is less prone to this failure.
  • High voltage batteries incur less resistance in cabling and conversion to household AC due to lower current flow and as such the system requires less accessories to operate.
  • Designing a high voltage battery system requires a battery inverter that is specifically designed for high voltage input. As of writing, the SMA Sunny Boy Storage 2.5 (battery inverter with inbuilt 2.5 kWh battery system) is compatible with high voltage batteries or hybrid inverters: SolarEdge StorEdge (single phase) and Fronius Symo Hybrid (3-phase). As such, high voltage battery system requires special accessories and thus, we are not confident that high voltage batteries would be adopted as an industry standard. Therefore, battery owners are effectively restricted to high voltage batteries due to the use of specialized high voltage battery inverters.
  • High voltage system naturally leads to a low current system that would shut-down intermittently to high current spikes (e.g. use of kettle, microwave and hairdryer) and as result there will be periods where batteries cannot accept current flow and this can last up to 1 minute each energy spike. In short, lower battery voltages offer better battery costs at higher system integration costs, whereas higher voltages turn that comparison the other way around.

Life Expectancy and Cost of Battery Systems:

The growth of battery technology has been slower than general electronic technology in history and it only this year the growing public interest in battery has expedited R&D and as a consequent, prices are starting to drop over the next 5 years.

  • Lithium batteries are estimated to last 5,000 full cycles which equates to about 15-16 years of operating life in a typical household. This life expectancy is dependent on the depth-of-discharge (DOD) that is targeted (household is recommended to have 80% DOD), of which lower DOD results a longer lifespan. Therefore, under-sizing a battery system is a detrimental option overall.
  • Industry standard of batteries typically covers 10-year limited warranty (parts defect and workmanship) and 60% energy retention after 10 years. Warranty is also dependent on operating conditions.
  • The payback period of battery systems is expected of have an average ROI of 10 years in a well-designed system as of current writing, this includes the expected projection of electricity prices of 5% increase per annum.
  • Battery Prices are expected to decrease over the next 5 years as more manufacturers move into household battery systems and as well as Inverter manufacturers becomes more competitive.
  • Energy market is expected to shift to Time of Use tariff as more smart meters are being implemented in households. This means that energy charges would vary dependent on peak hour usage, but it does not mean overall electricity fee would increase.


We recommended batteries in scenarios where there is substantial night-time electricity use and there is adequate excess solar electricity to be stored for night-time use. Otherwise, we believe that the current battery offering imposes a first-adopter premium and not suitable for general households. The current battery standards by Australia Standards has not caught up to the recent technology and therefore battery systems are not recommended as a set-and-forget investment as of now. We believe battery technology would revolutionize the structure of the current electric market and effectively decentralize the system, making grid electricity cheaper in the long run.

We have been designing battery systems for 30 years in homes that have no access to the grid and have customers with systems running for more than 10 years on older technologies and still going strong. Should you have any further inquiries, please do not hesitate to give us a ring at (08) 8344 7298 and allow us to design the best system to suit your needs.

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