looking for document on the maintenance requirements (costs) of a back-up battery bank

bcguy · May 2013

This is for a High school solar grid tied system. The school is also the local emergency shelter, so it might make sense to have battery back up, but the school is worried about on-going maintenance of the batteries. Anyone know of a paper or study that could be used as part of a proposal?

Thanks,

Dave E

niel · May 2013

Re: looking for document on the maintenance requirements (costs) of a back-up battery ba

not off hand. it sounds like it could be set up much like the cell towers, but feasability really depends on the loads the school would want backed up and for how long. most i would think opt for a generator as a backups in a school and would most likely be a very huge affair to use batteries. the backups could be geared more for things that are more critical and sensitive to the interruptions such as computers for example. most schools have small ups security lights so that should not be too much of a factor unless you would try to centralize the batteries and run lots of wiring to them. not easy or economical to do that for the lights. small ups are also usually on computers, but usually only for a shutdown procedure rather than continuing operation during an outage.

being pvs in a gt system are already there, is it the school's intention to change to a hybrid system for some isolated circuits? or just add the batteries and back up inverter with a self contained charger for individual circuits? the latter will only charge the batteries if the grid is present or the generator is running.

BB. · May 2013

Re: looking for document on the maintenance requirements (costs) of a back-up battery ba

Scale of problem will help too... Is this planned just for emergency LED lighting (relatively small system)--Or something larger?

And, batteries are certainly a sore point for any emergency power system... We had a power failure at our office decades ago--The emergency lights did not even blink on for a few minutes). A few days later, a pallet full of a dozen lead acid storage batteries outside the power room.

In the end, this needs to go back to basic planning. Are they looking for an hour of backup lighting until emergency gensets turn on and/or building is evacuated or what...

Either you make the system small enough that they just replace two to four "golf cart" sized batteries every 2-3 years (perhaps AGM/Sealed batteries if nobody is ever going to check electrolyte levels). Or a small Honda/Yamaha inverter/generators configured to run with a few hundred pounds of propane and the engines are "pickled" until needed (two or three--backup, spare, and spare for the spare). If this was my home--I would probably go with the propane and pickled engines (basically this is what I do now, but use gasoline instead with fuel stabilizer--and change fuel once a year). Perhaps put the whole thing on a small trailer (easy to take somewhere for service, pull out of storage for use in an open area with power cord to point of use).

Otherwise, a real official backup system should be exercised once a month and have normal inspections/maintenance performed. Ain't going to be cheap to do "right"...

If the high school still has any auto shop type classes, I could see this done as an ongoing class project to setup and perform the maintenance. That would be about the cheapest way to go and give some good education too.

-Bill

YehoshuaAgapao · May 2013

Re: looking for document on the maintenance requirements (costs) of a back-up battery ba

bcguy wrote: »

This is for a High school solar grid tied system. The school is also the local emergency shelter, so it might make sense to have battery back up, but the school is worried about on-going maintenance of the batteries. Anyone know of a paper or study that could be used as part of a proposal?

Thanks,

Dave E

You're not going to power a whole school off of a battery bank unless you got some big budget bucks. Probably more realistically it would be the lights and such that need to stay on when the power goes out (exit signs, one or two fixtures per classroom, etc..). For a shelter (if it is only a part of the school building), the (non)inclusion of HVAC will be a huge factor of capacity planning. You need to figure out scale before anything else. You can put two small panels panels on a straight grid tie system (or even on a cart with a portable grid tie inverter plugged into an outlet), but when the batteries get involved, the batteries and inverters need to be able to handle the load.

westbranch · May 2013

Re: looking for document on the maintenance requirements (costs) of a back-up battery ba

It just struck me that if you are only going to use this backup in the school for REAL emergencies, essentially you will need a system similar to the ones used by Telecom outfits for grid failures.
An AGM or similar type battery that will just sit there on float day in and day out until it is needed.
Difference is that the battery in these setups is meant to deliver FULL power until the grid is back on or a genny kicks in.
A FLOW battery may be a better type, new to the market, here is on in Australia http://redflow.com/
hth

looking for document on the maintenance requirements (costs) of a back-up battery bank

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