Home Battery Systems – The Next Technology

by John Brian Shannon – Originally posted on JBS News

Home Battery Systems augment your energy needs

Home Battery Systems can store electricity from solar panels, lower utility bills, and provide electrical power during utility company power outages.

Ever since lower priced solar panels hit the market it has become obvious that home battery systems are the next step for our modern, but still evolving, energy grid.

Installing solar panels on your rooftop has never been easier as panel prices have fallen by 80% over the past two years and installation rebate programs are generous in many jurisdictions. But getting all that free daytime energy from the Sun won’t do you much good unless you can store it for later use.

Having a home battery system allows you to store the energy that your solar panels collect every day.

Solar power can make economic sense in many locations. But solar with a battery system will rock your world! OK, maybe not rock your world, but it makes a lot of sense if such a home energy storage system can be had for a reasonable price.

Home Battery Systems can make sense even without solar panels

Without a home battery, you can still sell your excess solar generated electricity to the grid if your utility has a net-metering programme. But some of your profit is eaten up when you must buy back some of that electricity after the Sun sets, at a higher price. Yes, every day of the year.

For homeowners, having home energy storage means you could save a lot of money over ten or twenty years if the system is cost-effective to begin with — and a battery system is a wonderful thing to have during utility company power outages.

If you live in a jurisdiction where you can buy electricity from your utility company at a very low rate during certain hours and store that energy with your home energy storage system for later use, that can work for you — regardless if you have solar panels or not.

Peak rates can be $0.38 per kWh (or higher), while off-peak rates can be $0.08 per kWh (or lower) making the peak rate about five times more expensive in this example, than the off-peak rate.

Prognosticating ten or twenty years out, who’s to say what electricity rates may be? There always seems to be a reason to hike the rates.

Your home or business can run on the power from your stored electricity during high electricity rate periods, and sometime past midnight, your system can be scheduled to automatically connect to the grid and recharge itself at the lowest possible rate.

Home Battery systems protect you during power outages

Apart from collecting solar energy all day, or saving money due to electricity rate fluctuations, (or both), having a stored energy system can protect you from utility company power interruptions, especially for those in rural areas or other areas where power outages are common.

For homeowners in rural areas and who may be subject to frequent power service interruptions, having battery backup can make sense, particularly during storms, typhoons, or very hot or cold weather.

Of course, the old standby has always been an expensive-to-fuel diesel generator and the noxious fumes that go along with it.

Emergency service providers, schools, and other important government buildings and businesses could also benefit from such in-situ battery systems. We can look at a veterinary clinic or other examples where uninterrupted electrical power is important. With stored energy backup, electrical power is automatically restored within a few seconds and the vet can continue with the days’ operations on her four-footed patients — just that easy!

SolarCity and Tesla combine forces to offer home energy solutions

It is interesting to note that Tesla is working with Solar City to offer home batteries, using their proprietary Electric Vehicle (EV) battery technology. A fascinating development and one that holds game-changing promise.

  • Home Battery System by Tesla.
  • Home Battery System by Tesla and SolarCity.
  • Recycled Electric Vehicle batteries still have 70% life

GM wants to use old Chevy Volt batteries and give them a second life as home batteries. GM says that even after ten years of powering your electric vehicle, an EV battery still has at least 70% of the power it had when it was assembled.

In many cases, when an EV battery has reached the end of its life in an automotive application, only 30 percent or less of its life has been used. This leaves a tremendous amount of life that can be applied to other applications like powering a structure before the battery is recycled. — Pablo Valencia, GM senior manager of battery lifecycle management

Innovations like recycled EV batteries will pave the way forward to a viable and affordable distributed energy future and are an efficient second-use of this technology.

EV batteries store a huge amount of power, enough to easily power a home for two or three days in the case of a service interruption — and in the case of storing energy for everyday use during peak rate periods, would be well within their capabilities.

Stay tuned, because this story is just beginning!

Smoothing the Flow of Solar Power in California

by Dr. Imre GyukU.S. Department of Energy.

This EnerVault flow battery stores power from the solar panels and releases it as needed. | Photo courtesy of EnerVault.
This EnerVault flow battery stores solar power from the solar panels and releases it as needed. | Photo courtesy: EnerVault.
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Yesterday, an almond grove in California’s Central Valley hosted the opening of the world’s largest iron-chromium redox flow battery. Originally pioneered by NASA, these flow batteries are emerging as a promising way to store many hours of energy that can be discharged into the power grid when needed.

Traditionally, electric generation follows the demands of the daily load cycle. But as more sources of renewable generation such as solar and wind are integrated into the power grid, balancing demand and generation becomes more complicated. With energy storage, we can create a buffer that allows us to even out rapid fluctuations and provide electricity when needed without having to generate it at that moment.

Unlike other types of batteries, which are packaged in small modules, iron-chromium flow batteries consist of two large tanks that store liquids (called electrolytes) containing the metals. During discharge, the electrolytes are pumped through an electrochemical reaction cell and power becomes available. To store energy, the process is reversed. With Recovery Act funding from the Department’s Office of Electricity Delivery and Energy Reliability, California energy storage company EnerVault has optimized the system to create a more efficient battery.

This pilot project in Turlock, California, can provide 250kW over a four-hour period, helping to ensure the almond trees stay irrigated and the farm is able to save money on its electrical bills.

This is how the system works:

The almond trees are most thirsty between noon and 6 p.m. The farm uses nearly 225 kW of electricity to power the pumps that get the water to the trees. Onsite solar photovoltaic panels can supply 186kW at peak power, not quite enough energy for watering the trees throughout the day. The balance could be taken from the grid, but grid electricity is most expensive from noon to 6 p.m.

This is where storage enters.

At night electricity is inexpensive, so the batteries begin to charge up. In the morning the solar panels help top them up the rest of the way. Then, during expensive peak periods, the needs of the trees are satisfied by solar and flow batteries — renewable energy optimized through storage.

While the Turlock facility is a unique application, flow batteries are not just for thirsty almond trees. For example, they could be an especially good solution for small island grids such as Hawaii, where severe wind ramps or rapid changes in photovoltaic generation can destabilize the local grid, or at military bases that need to maintain mission-critical functions.

Similarly, flow batteries paired with renewables can be used in a resilient microgrid that can continue to operate when disasters strike and power outages ensue.

In the face of changing climate conditions, energy storage and grid resiliency have become more critical than ever. Flow battery technology is expected to play a vital role in supporting the grid both in California and across the U.S.

Additional Information:

Dr. Imre Gyuk
Dr. Imre Gyuk is the Energy Storage Program Manager, Office of Electricity Delivery and Energy Reliability.
HOW DOES IT WORK?
Iron-chromium flow batteries store liquids, called electrolytes, that are pumped   through an electrochemical reaction cell to release power. The process is reversed in order to store energy. This means that the batteries can store energy from the grid, and release it when the load is heaviest.