Take your grid connected solar system to the next level by adding a Solar Battery - aka Home Battery or Home Storage System. Storing your own solar power will give you greater independence from the corporate energy retailers and will increase the benefits of your solar system.
Sizing the solar batteryA typical Aussie household ("working family") only uses about 30% of its total energy needs during sunshine hours. So a Solar Battery sized to offset most, if not all of your energy needs should be around 70% of your daily consumption (in kWh).
Of course, smaller batteries can also be installed and still have a great impact on your electricity bill as well as your carbon footprint. Generally, Solar Batteries with a capacity of about ⅓ of your daily consumption already double your solar yields.
| Average use per day (kWh) |
Best Value battery (kWh) |
Min. required solar (kW) |
Best Size battery (kWh) |
Min. required solar (kW) |
|---|---|---|---|---|
| 8 | 2.4 | 1.5 | 5.6 | 2.5 |
| 12 | 3.6 | 2 | 8.4 | 3.5 |
| 22 | 6.6 | 3.6 | 13.5 |
5.5 |
Tesla Powerwall 2
Tesla Powerwall 2 in combination with its integrated AC inverter makes a powerful Solar Battery system with emergency backup. The 13.5kWh Powerwall 2 is sized for installation in large family homes or even small businesses.
Powerwall 2 is rated for outdoor installation and requires no maintenance; operation is completely automated. The system is managed by the Tesla Energy Gateway. If permanently connected to the internet, Tesla warrants the battery for 10 years and you can monitor your home via Powerwall App.
Tesla Powerwall 2 AC System includes:
- 1 x Tesla Powerwall 2 AC (Lithium Ion)
- 1 x Tesla Energy Gateway
- Labels, brackets, breakers, cabling
- Installation within 50km of Nimbin
Enphase - Home Energy Solution
The Home Energy Solution is an intelligent and modular storage system designed for residential households. The 2.4kWh Kit is suited for working individuals or couples but the system can also grow with the family.
The Enphase system comprises of a communication gateway and 2 x 1.2kWh solar batteries with integrated inverters. It continuously monitors the electricity production and consumption to decide when to export, import, charge and/or discharge. If there is a permanent internet connection, such data can also be accessed in a browser or mobile app.
The Enphase Home Energy Solution includes:
- 2 x Enphase AC battery (Lithium Iron Phosphate)
- 1 x Envoy-S Metered Communication Gateway
- Labels, brackets, breakers, cabling
- Installation within 50km of Nimbin
Note: an internet connection OR mobile reception is required to commission the system.
Why should I add a Solar Battery?
Graph #1
Regulated feed-in tariffs (FIT) are a thing of the past; most energy retailers only offer 6-12 cents per exported kWh (if anything) while charging 30 cents for imports. It is therefore more economical for households to use that home-made power, however solar production peaks during midday, but the demand is in the mornings and evenings.
Graph #1 shows a typical 3-bedroom home of a working family (using 8kWh/day) with a net-metered 1.5kW solar power system. About 33% of the household's energy is supplied by the solar panels.
Graph #2
Solar Batteries store some or all of the generated solar power which otherwise would have trickled into the grid at a low pay rate. They are automatically recharged when your solar panels produce more power than is required by the household; at night or during cloudy periods, electricity is drawn from the batteries. Even small batteries can make a big impact.
Graph #2 shows the same 3-bedroom home, still with the 1.5kW solar system + 2 x Enphase AC Batteries (2.4kWh). Now the yields from solar nearly doubled to 65.1%.
Graph #3
The fortunate owners of larger solar systems (3+ kW) can add bigger batteries which would meet the bulk of the household's electricity needs; the grid will only be ever used to "top up" or as last resort. Please note, Home Batteries are currently not capable of powering a house during a blackout.
Graph #3 shows the same 3-bedroom home with a 3.5kW solar system and a Tesla Powerwall I (6.4kWh). Now the yields from solar are well above 90%.
Installation
Home Batteries must be installed by a licensed electrician, and ideally by someone who understands batteries. It should not take too long to upgrade an existing solar system provided that there's enough room for all equipment. Note: even outdoor rated batteries should not be located in direct sunlight.
SMA based Solar Systems
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).
