Friday 5 June 2015

Batteries, Batteries, Batteries!

Posted at 1:54 PM

Batteries, Batteries, Batteries

Last month. Tesla hosted a PowerWall announcement party by which has really stirred up the conversation about batteries and energy storage.  People are talking about energy storage with and without the grid. Did anyone else watch the announcement party and think of Steve Jobs announcing another version of the I-Pad or I-Phone? Based on the call and emails we received in the days after the announcement party, it sounded like there were some people that were nearly ready to camp out to be one of the first to get theirs.

We love the energy that Tesla CEO Elon Musk has put back into this conversation (pun totally intended).

Here are three ways that home energy storage are being implemented today.

Peak Shaving

This is one way that Elon Musk talked about. It has real value in high energy priced areas of the country – like California.  Even more specifically in high-energy rate areas with with peak energy premium rates. In this scenario, there are no solar panels and the grid charges the batteries,

With peak shaving, the battery bank is charged by the grid during the evening or during ‘off-peak’. During the day, the battery bank runs the home , avoiding  energy that is priced at ‘on-peak’ rate. Southern California Edison charges 46¢/kWh on peak (2pm to 8pm) and 11¢/kWh ‘super off peak’ (10pm to 8am).  For many homeowners, this can be a huge energy bill saver. That’s a 36¢/kWh savings for 6 hours a day.

Here in Wisconsin, we have some of the highest energy rates in the mid-west. While this system will most certainly work here, it most likely will not have the same financial results. Wisconsin Public Service currently offers off peak rates (10pm to 7am) of 6.12¢/kWh and on peak rates of 23.3¢/kWh (between 4pm and 8pm). It would take a special circumstance to make the 17¢/kWh savings over a 4 hour period work.

A little pencil to paper would help decide if peak shaving would work for you.

Energy Back-up Systems

This could be achieved with either the grid or with a solar PV array.

In either case, the homeowner indicated a couple or a few ‘critical loads’ – electric equipment that they want to be able to operate in the event of a grid outage. Typically a well pump, refrigerator, freezer and furnace blower are devises that would removed from your main breaker box and placed into a ‘critical load’ panel. When the grid fails, the homeowner has a set amount of energy to use for these appliances. Typically, these systems will provide about 24 hours of energy to these devices.

When a homeowner charges that battery bank with the grid, when the juice is gone it cannot be recharged until the grid returns.

If you have an AC Coupled system with a PV array, you can continue to re-charge your battery bank as the solar resource allows. Additionally, your PV array isd grid tied, so you will realize vale for your solar generated energy even when your batteries are charge. 

Off Grid Energy

In this situation, a solar array and/or a wind turbine, generator, or the like charges the battery bank. The grid is not used at all in an off grid system.

This is what many of our phone calls and emails asked about after the PowerWall announcement party. Without doubt, this system can be installed for any home. It does take a higher level of energy analysis of the home, matched with much more careful design of the battery bank, PV array and supporting equipment. Using an off-grid system, the homeowner is now essentially on an energy budget. Striving to use as close to or less than the design daily load of energy. While a generator is very useful during periods of low solar insolation, most off-grid system owners don’t like to rely on it.

While you might think that the PowerWall is the only breakthrough in energy storage technology. It most certainly is not. There are a myriad of choices in battery technology when designing your peak shaving or battery backup or off-grid system. At North Wind, we have skilled electricians and system designers who can help anyone with a desire to invest in energy storage for their home or cabin.

The announcement of the PowerWall reminds us that energy independence is not a myth. Residential energy storage, while not necessarily mainstream, can no longer be called fantasy. The PowerWall is just one way that we are changing our attitudes towards energy distribution and energy storage. But for those that cannot deny the allure of the sleek and sexy Powerwall, you’ll need to wait. The PowerWall is not expected to be available until late summer or early fall.