Emergency Energy: Options for Living off the Grid When Necessary

Comment

Comment by Curt Kinder on November 21, 2012 at 6:16pm

20% sounds about right.

Batteries will need continuous trickle charge - not much, but it adds up, particularly with a big array of flooded cells, a bit less if AGM, but those are really pricey.

The size of battery bank and inverter needed to run just a few loads for several cloudy days runs into some serious bucks.

Relative inefficiency of ICE generators is not a problem if they are rarely run. Some gennies have an exercise cycle that runs them automatically for a few minutes weekly or so.

Comment by tedkidd on November 21, 2012 at 9:26am

Curt, 

My understanding (and recollection based upon what a friend in the solar business told me) is battery charging loss is about 20%.  

He also said those losses ONLY happen after the batteries are drawn down.  Furthermore, batteries NOT drawn down tend to last almost indefinitely.  

If batteries are only drawn down, say, once a year during a power outtage, the 20% loss becomes pretty irrelevant.  Particularly when compared to the incredible capital and mechanical inefficiency of the alternative, 20% efficient combustion engines that need to run monthly and need annual maintenance. 

Comment by Curt Kinder on November 17, 2012 at 1:49pm

Several major oversights and oversimplifications

1) Left unsaid are the losses associated with constantly charging and discharging batteries as well as maintenance of flooded cells.

2) Geothermal systems may need relatively little electricity to operate and are often the least cost per million delivered btu (I personally own a WaterFurnace, and it works well) but batteries or "a small generator" ain't gonna hack it. Even with soft starters, inrush currents require a big generator or hulking inverter to manage. Only the biggest RE systems can cope with a multi-ton geo heat pump.

Small minisplit air source heatpumps are probably better at storm resiliency - much more able to be managed by a backup power source. Redundancy and scalability are significant advantages

3) The average urban dweller likely to be a good candidate for an electric car is very unlikely to have the roof area or capital needed for a solar array big enough to keep an electric car charged as well as run the house. There are some intriguing possibilities wherein the car's battery bank doubles as a house , but I didn't see that in the white paper.

For those irritated by the need to supply email to download this limited-value white paper - no worries - site does not verify email, just put any old thing in the field like "curt@nospam.com"...or save yourself the time and browse elsewhere.

Comment by CleanEdison on November 16, 2012 at 12:53pm

Sean,

We just thought it was worth looking into, even if the conclusion is still generators. We actually found that with energy storage incentives and TOU rates in California, grid-tied solar PV with battery backup could be achieved for the price of a good generator. Obviously, this is not the case in most places, but it's always a question worth asking after major blackouts.

Comment by Sean Lintow Sr on November 14, 2012 at 4:45am

Maybe I am in just one of those moods but let me call this a crappy BS marketing gimmick. This isn't a blog post & clicking your link to fill out a bunch of info to get a "white paper" is ridiculous. The answers are generators (whether it be a powered by gas, diesel, propane, or your Prius using an inverter). wind, solar, or thermal generally tied in to a battery bank - tell me I honestly missed something & I just might fill out the form...