April 3, 2016: Home Battery Updates

Solarquotes.com.au  is an excellent source of up-to-date information about solar power and home battery storage systems. They have put together a ‘Battery Storage Comparison Table’ which compiles a lot of useful data about the range of available (or soon to be so) battery systems on the Australian market.

Home Battery Comparison Table from solarquotes.com.au

This recent article from solarquotes describes how the actual installed cost of a Powerwall is proving to be double what was expected based on the initial press release from Tesla only eleven months ago. The conclusion from the article is that we need to consider the installed cost per warranted kilowatt-hour in order to realistically compare the many energy storage systems that are appearing in the market. They will be adding a row to their comparison chart to this effect which should greatly assist with the (increasingly complicated) decision of whether to install home batteries.

Homes with Electric Cars already have Battery Storage

An important thing to remember when considering home energy storage is that electric vehicles (EV’s) have big batteries.

Electric Vehicles have large storage batteries

As my good friend, Manuel Cilia of Cilectric Pty Ltd, likes to remind me, anyone that has an electric car already has a lot of energy storage potential. Our Mitsubishi Outlander PHEV came with a 12kWh battery and some EV’s have batteries as large as 60kWh. To put this in perspective, the Tesla Powerwall is rated at 6.4kWh so a big car battery might be 8 times bigger and have enough capacity for a 500km trip. Yet most people drive less than 50km a day. So there is plenty of capacity for car batteries to be able to store power during the day and send it to the home, or to the grid, during the evening peak. This is known globally as a Vehicle-To-Grid or V2G System. All new EV’s in Japan are required to be equipped with a CHAdeMo charging plug which can allow for fast charging as well as V2G discharging of the car battery. Ironically, and unfortunately, when the same vehicles are shipped for sale in Australia, the CHAdeMO plug is removed. My Outlander just came with a J1772 socket that allows for charging but not for V2G exchange of power. This is disappointing because it is looking increasingly likely that a three way exhange of power between houses, cars and electricity grids will be a key to reducing our dependence on fossil fuels.

ORNL Envisions the Future of Home and Vehicle Energy Exchange

Carbon-fibre, 3D-printed, power-sharing, vacuum-insulated house and car. (Source: Gizmag)

I’ve written about this project from the Oak Ridge National Laboratory before from the perspective of 3D printing but it’s worth revisiting it from the point of view of house and car energy generation, storage and exchange. In this vision of the future, both the house and car have batteries and both are capable of generating electricity, the house via solar panels and the car via an internal combustion engine which, in this situation, operates as a back-up generator. The two systems can exchange energy via a wireless energy transfer system. So the house can make energy with its solar system and store power in either the car batteries or the house batteries. If the car is at home and the house runs out of stored energy, it can draw from the car batteries or the car engine can start and act as the power generator for the house. In the medium term I think this will prove to be the future of our homes, cars and the way we use energy. The Greeny Flat is not far away from having this sort of capability. We have the home energy generation, we have the car batteries and petrol engine that can operate as a generator, all we are missing is a home battery system, a two-way connection and a smart controller to manage the flow of energy.

I envision a future in which every home and car has these capabilities and we are all connected to a smart grid in a way which allows us to exchange energy between our homes, cars and each other. This would allow us to maximise the efficiency of each component as well as the system as a whole. When demand is high there would be thousands of home and car batteries (as well as petrol generators) that could feed power into the grid (thereby reducing the peak loads) and when demand is low and renewable energy generation is high, thousands of batteries available to store the energy for later use.

Energy Conservation Comes First

The latest edition of Renew Magazine includes another good article by Lance Turner about the latest developments in Home Energy Storage. The article lists 22 different battery storage systems that are either available now or should be available to buy in 2016. The gist of the article is that the cost of energy storage is expected to drop rapidly over the coming years. So Lance’s conclusion is that, ‘with battery life expected to be around 10 years, it is generally not yet economically advantageous to a install battery system for most grid-connected homes.’  If your ‘primary motivation for considering a battery system… is to offset electricity cost by making better use of your solar-generated electricity, then you are best to wait until system prices have dropped’.

It was refreshing to read Lance’s advice that, ‘while you are waiting for prices to come down you can get to work on improving the efficiency of your home to minimise energy use and hence the amount of storage required’. This is a VERY important point that is often ignored or overlooked in discussions about Renewable Energy and Battery Storage. It is vital to REDUCE your energy requirements as much as possible BEFORE considering how much solar power and energy storage you need.

Making the Most of the Sun

On the subject of energy efficiency and reducing energy requirements, I’ve written a lot about the many benefits of Passive Solar Design.

The FlipFlic solar powered blind opener (source Gizmag)

Good Passive Solar Design works to keep a home warm in winter and cool in summer. It relies on the fact that the sun is high in the sky in summer and low in the sky in winter. If the home’s orientation is correct, the right amount of eave overhang on the roof will keep the summer sun out and allow the winter sun in to warm the home. This can be greatly assisted by the use of good insulating blinds which can help to keep summer sun out and winter warmth in. However blinds work best if someone is home during the day to open and close them at the right time. I have long lamented the lack of a simple, affordable system for automatically opening and closing blinds. Now there is hope on the horizon with a device called the FlipFlic which is currently seeking funding on Kickstarter. As described in this Gizmag article, the Flipflic is a solar-powered device for opening and closing venetian blinds and only costs US$60. While venetian blinds can be useful for keeping out summer sun, they are next to useless for keeping in winter warmth. So the FlipFlic is a step in the right direction but I will be holding out for future releases from the company. According to Gizmag, ‘a version for blinds that are controlled by cords or strings is said to be in the works’ and that will have the potential to really improve a home’s energy efficiency.

New Renewable Energy Surpasses New Fossil Fuel Energy Globally

According to this article from greenworldinvestor.com, for the first time ever ‘RE capacity addition was more than 53% of the total global capacity addition in 2015, and it was the first time that RE was more than half of the total capacity addition.’ Renewable Energy still only accounts for less than 10% of global energy capacity however it is heartening to note that the tide seems to be turning in favour of Renewables.