Electric Car Batteries And How These Will Revolutionise How We Power Houses

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The issue with solar power these days is not that we can’t produce enough power (because we can), but actually we are limited by our ability to efficiently and economically store the electricity generated by the sun in batteries. Industrial battery technology has always been too expensive, too large, doesn’t last long enough and is mostly problematic for the consumer, unless you’re really passionate about going off the grid, or are forced into a situation where it’s the only viable way to store electricity.

Picture: Auckland house generates its own power from solar panels
Picture: Auckland house generates its own power from solar panels

The government and power companies aren’t all that interested in setting up incentives for feeding your renewable energy back into the main power grid, and when you do feed power back, its less that what you buy each unit for e.g. 24 cents you buy, 7 cents when you sell. Their side of the story is, most of the power in New Zealand comes from renewable sources and they have invested billions of dollars into this infrastructure over decades, and need to make money from it. The public’s side of the story is, they paid for this infrastructure, power bills are expensive, and hundreds of millions of dollars are continuously been invested into more power infrastructure, to meet the supply of inefficient houses. It’s a highly stagnant situation.

Luckily we have companies like Tesla Motors, innovating electric car technology. Tesla Motors, named after the great inventor Nikola Tesla, are getting allot of media attention, and one in particular reason is the development of an affordable battery.

Picture: Tesla power wall connecting to an electric Tesla car
Picture: Tesla power wall connecting to an electric Tesla car

The reason why this is all interesting and important is the electric car industry is on the tipping point of making successful commercially powered electric cars available to all, and the battery is at the heart of it. Battery technology is now at a stage where sizes of batteries are small and manageable, the electrical storage capacity is big enough to power a house or car, and most significantly the battery price is slowly becoming affordable. This is only the tip of the ice burg with how it will further develop and be applied to other practical areas in our lives.

According to Tesla Motors, battery units can be purchased for approximately $5100 NZD, with a maximum storage capacity of 6.4kWh’s. Typical battery storage units used to power a house will cost $10,000 NZD and upwards, with the solar panel system been approximately the same price to the battery system.

The key here is energy optimisation, before installation of any power generating or storing devices. The overall energy used in the house needs to be minimised from the outset through good design practice. How this is achieved typically relates to good floor plan orientation to the sun, good insulation practice, energy efficient appliances and passive design strategies such as, passive solar gain, thermal envelope design, airtightness etc.

Picture: New Zealand houses consume 11,410 kWh/ per year on average
Picture: New Zealand houses consume 11,410 kWh/ per year on average

The average power consumption for a typical 205sqm New Zealand house, according to BRANZ (Building Research Association of New Zealand) is approximately 11,410 kWh/ per year, or an annual energy index 55.7 kWh per/sqm/ per year. This figure is high, and illustrates the inefficiency of how much energy we actually require to power our homes.  To give you a comparison, houses that are designed for energy efficiency can achieve approximately 5000 kWh per year, or less, with an average energy index of 24.4 kWh per/sqm/ per year.

So, what all this means is the idea of an energy self-sufficient house, that requires no grid connection is about to become economically viable for the public.  When the payback period for the initial investment is achieved within 5-10 years of purchase, and the solar panel system will last 20-30 years, this then radically changes the energy supply playing field. Through good design practices most New Zealand homes could significantly reduce their energy consumption given the correct practical advice, but even if they don’t, battery technology will only improve and become more affordable. The consumer will then be given the choice to choose for themselves how to power their houses, whether or not that will be through the traditional power company, or by solar power with the addition of affordable high capacity batteries. I know which one I would choose.

Written by Duncan Firth, www.solarei.com
Technical review by Jarek Pole, www.indepower.co.nz

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