Grid Connect with Battery Backup Power

Self-Consumption vs Energy Exports

Storm coming in, red clouds

With the demise of regulated feed-in tariffs (FIT) we started designing our grid connect solar systems with a focus on "self-consumption". Most electricity providers only offer 6-8 cents per kWh (if anything) while charging their customers 30+ cents for the same kWh. At this exchange rate it is obviously more economical to consume than to export.

Residential consumption usually peaks at 8am and 8pm but due to the nature of the technology, solar production is at its highest between 10am and 2pm.

Oversized Solar Systems

There are already thousands of potentially oversized solar systems in Australia. Habits and energy usage change over time; family members may have taken on day time jobs, started school or left the nest entirely.

Furthermore, solar systems designed under the now closed NSW Solar Bonus Scheme (60 cent per kWh) may have changed ownership resulting in an inferior FIT (and if ownership has changed, did the gross meter get changed to net metering?) The scheme will expire on 31.12.2016 and will leave many households with too big a solar system for anyone to profit but the electricity providers.

Last but not least, some of the more aggressive sales reps may also have omitted that working families do not benefit as much from a grid feed system as no-one would be home during peak production hours. Needless to say, our system designs have always considered individual needs over commercial gains. Have a look at our solar savings calculator that visualises energy usage and production.

Adding Batteries

consuming solar energy on batteries, copyright SMA Solar Technology AG

A grid connect solar system can be taken to a whole new level by adding deep cycle batteries. Such batteries can be much smaller than those used in stand-alone solar systems as the convenience of the electricity grid remains at your disposal. The batteries serve two purposes:

  1. Increase self-consumption
  2. Provide backup during grid failure


Wouldn't it be nice to have solar energy available around the clock – even after sunset? This is now possible with SMA Sunny Island systems.

A Sunny Island inverter automatically charges the connected batteries. When your solar panels produce more than you need, the Sunny Island prevents the (existing) inverter from feeding into the grid until the batteries are fully charged. In the evening (or during cloudy periods), electricity is drawn from the batteries hence maximising self-consumption. The grid will only be ever used as "top up" or last resort.

Backup Power

During a blackout a grid feed system disconnects from the grid - not producing any electricity either for the grid or for the supply of your house. A grid connect battery backup systems includes a changeover switch that detects grid outages and automatically switches to battery mode. The upgrade from a self-consumption battery system to a battery backup systems is not very expensive ($495) and strongly recommended if you live out in the bush. Ideally your household's electrical circuits are separated in essential (lights, fridge, etc.) and non-essential loads (pool pump, hot water system, etc.) to avoid excessive battery use during long blackouts.

Upgrade your Grid Connect System

Most existing grid connect systems with an SMA inverter (e.g. Sunny Boy) are "battery ready" making the retrofitting of a SMA Sunny Island system seamless. The newer generation of SMA inverters allows for battery charging AND grid export (in case of excess). Older SMA inverters can still be used for battery backup and/or increased self-consumption (without grid export).

Sunny Island 3.0

Sunny Island 3.0

Sunny Home Manager
Sunny Home Manager

Intelligent Energy Management

LG Chem RESU 6.4EX Battery Pack
LG Chem

6.4kWh Lithium Ion Battery Pack

SMA - Self-Consumption Upgrade

This 48V battery system with maintenance free batteries will provide a significant part of your night time energy needs (~5.7kW/h).

If you have an SMA based grid connect (grid-feed) solar systems this upgrade kit is all you need to increase self-consumption and is the next step in weaning yourself from the big energy retailers.

The upgrade kit includes a Sunny Island 3.0 or 6.0 Inverter/Charger with remote control unit and a Sunny Home Manager with accessories, a 48V lithium ion battery pack, all cables and required signage as well as installation (in Northern Rivers). Recommended for existing grid-feed systems from 3.5kW of solar panels.

Price: TBA, installed*

house wired with batteries - copyright SMA Solar Technologies AG

SMA - Battery Backup

The self-consumption upgrade does not include the optional changeover switch. However, for an extra $495 this switch can be added, giving you power around the clock, even during blackouts. Additional wiring may be required depending on your circumstances.

small get-a-quote icon

*Conditions: Installation site within 50km of Nimbin; single phase power; undercover area for batteries and inverter/charger near existing inverter; SMA inverter with frequency-dependent active power limitation capability.

Suitable SMA Inverter

Sunny Boy (SB)Firmware
SB 1300TL-10 / 1600TL-10 / 2100TL-10 4.52
SB 2500TLST-21 / 3000TLST-21 2.50.41.R
SB 3300-11 4.03
SB 3800-11 4.02
SB 2000HF-30 / 2500HF-30 / 3000HF-30 2.30.07.R
SB 3000TL-21 / 3600TL-21 / 4000TL-21 / 5000TL-21 2.51.02.R
Sunny Mini Central (SMC)Firmware
SMC 5000A / 6000A 1.50
SMC 6000TL / 7000TL / 8000TL 3.32
SMC 7000HV 1.81
SMC 7000HV-11 2.21
SMC 9000TLRP-10 / 10000TLRP-10 / 11000TLRP-10 1.40
Sunny Tripower (STP)Firmware
STP 5000TL-20 / 6000TL-20 / 7000TL-20 / 8000TL-20 / 9000TL-20 2.50.01.R
STP 8000TL-10 / 10000TL-10 / 12000TL-10 / 15000TL-10 / 17000TL-10 2.51.02.R
STP 15000TLEE-10 / 20000TLEE-10 2.54.03.R

We install solar systems in Northern NSW and Southern QLD.

Gold Coast (from Coolangatta to Southport), Nerang and Hinterland (Beaudesert) and out West (Warwick, Stanthorpe, Killarney)

Northern NSW (Tweed Heads to Yamba, including Evans Head, Byron Bay and Ballina); the Far North Coast Hinterland (Grafton via Lismore to Murwillumbah) and out West (Casino to Tenterfield, including Drake and Tabulam, as well as Woodenbong and Bonalbo)

For larger system we also go up to Brisbane or down to Coffs Harbour and even Glen Innes. Other places by arrangement.