Backup batteries for home on radar

[kristopher]

Backup batteries for home on radar
Storage units touted to counter power outages, peak-time rates

By HIROKO NAKATA
Staff writer

Storage batteries — especially those for home use — have been gaining attention since the March 11 earthquake and tsunami crippled the Fukushima No. 1 nuclear plant and sparked fears of blackouts hitting Tokyo during another sweltering summer.

Although large systems designed for industrial use are still mainly in the experimental stage, several home-use power storage systems are already on the market or on their way.

Given the seriousness of the disaster, use of the systems is expected to climb if prices drop enough.

Here are some questions and answers on storage batteries:

How do home-use...
http://search.japantimes.co.jp/cgi-bin/nn20110809i1.html



Juice on hand: NEC Corp. started marketing this battery-based power storage system for home use on July 18 amid public concerns that power outages might occur this summer because of the crisis at the Fukushima No. 1 nuclear plant and other reactor closures. NEC CORP.

[azul]

1. Stick that in the back of a pickup and you're good to go

wherever.

[TheWraith]

2. It's not that complicated, actually. You can do this now with lead acid batteries and an inverter.

They recommend the larger lead acid batteries made for boats and the like, but you can do it with car batteries. Typically a car battery will hold about 720 watt-hours at full capacity. The average American home consumes ~30,600 watt-hours per day, so you'd need around 45 car batteries to provide 24 hours of backup power for the average house. Assuming no change in usage, of course. $50 for a basic battery, * 50 batteries (to provide a little margin) = $2500, plus probably another $1000 for a charging system and a high enough capacity inverter. So $3500, all in.

You can see immediately why some people prefer to purchase a simple generator.

[Ready4Change]

3. As is often done with residential solar PV installs.

A lot of solar systems include battery arrays, so the system can store excess electricity collected during the day for use at night. These typically use larger batteries that are different than car batteries, so that they can be discharged more fully, and more often, without taking damage like a car battery does.

I know of one person who was considering installing solar who realized, in the process of specing out his system, that he was really only desiring the battery array part of it, so it could provide charge during periods where the grid in his area went down. He's now got a backup battery array that can keep his house running for about a day, which covers his most likely outage periods.

Now, what he SHOULD do, is set it up on a timer, so each day, when utility rates are highest, it disconnects from the grid, then recharges the batteries in the middle of the night, when rates are lowest. He's got the equipment any way, might as well use it in a way that decreases his bills and eventually pays for itself.

[kristopher]

4. Does he have time of use (TOU) billing?

Most accounts in the US are billed at a single rate that doesn't reflect either instant or daily supply/demand circumstances. As your example shows, getting policies like that implemented everywhere is a major undertaking that will pay off significantly in terms of conservation and/or efficiency improvements. What would be even better would a grid that's "smart" enough to micromanage the buying and selling of electricity down to the level of the individual home or auto. That would enable your friend to profit from investing in the home storage unit.
See: http://journals.democraticunderground.com/kristopher/567
Electric Vehicle Owners to Get Cash Back for Selling Power to the Electric Grid in Denmark (~$10,000)

Also, note that the story is from Japan. It is one in a series of similar articles that document a business move within the country to actively respond to consumer demand for technologies to help deal with the unreliable power supply resulting from dependence on nuclear power. Writ large, this demand amounts to a distributed grid that will move them away from centralized nuclear power.
Samples:
http://journals.democraticunderground.com/kristopher/648
http://journals.democraticunderground.com/kristopher/646

[TheWraith]

5. If you're not going off grid, batteries are not a good solution.

If you're doing alt-energy while still on-grid, you should get a grid-tie inverter, so that you can push power either way. It'll be far less hassle than the maintenance on a fleet of batteries.

If you're just looking for backup power, you should get a generator.