Adding batteries (this easy?)

Re: Adding batteries (this easy?)

dsun-
My wife and I had very similar ideas last year before we set up our own system (so yes I am still a newbie of sorts too).  We received some good advice right away that might be of assistance to you in getting started:

first don't worry as much at first about what brand, or style of equipment; first spend a bunch more time just learning how you use energy in your household.  This is huge, as the differences in your consumption (as well as the timing) can mean thousands and thousands of dollars.  So if you haven't yet, sit down and start doing some detailed analysis of your total consumption and write it all down; try to figure out your peak usage, average daily use, and what kinds of things that you could possibly cut back on if you needed to conserve energy for a bit.  We spent more time on this than any other aspect of the system in the beginning.

Second, it is really NOT a good idea to simply add more and more batteries to the system as time goes on.  There are a lot of reasons for this that others could probably put much clearer in great detail, but in a nutshell the batteries of different age and use will perform differently; the idea is that all the batteries will work together as one power source, so you really want to keep things as balanced as possible.  Think about what it would be like driving a truck under a heavy load with four totally different types of tire tread, at various ages; adding one new tire to the mix wont really help out that much.  You really are better off adding more panels and such later, but trying to accurately size your battery bank early on.  
This does present one big challenge for someone like yourself trying to start small and grow.  As we are starting to discover, we oversized our bank a bit too much for the size of our charging capabilities (2 110watt panels in parallel, and a generator with a small AC/DC charger), thus we sometimes have trouble keeping the batteries topped off all the way, and/or equalizing them.  So again the importance of knowing your load requirements, and trying to match them as best you can: by all means you don't want to undersize your battery bank, but be carefull of going too big if it will make it harder for you to upsize your production capabilities later. Try to make sure that you can charge your batteries up at something like a 5-10% ratio of the total Amp hour capacity (20 hour rating) of your bank; this can be in the form of solar, hydro, wind, generator, or all of the above.
It sounds like you are talking about an offgrid situation (like ours)?
If so I am assuming that you have, or will have a generator?
If so, take a look at various options and carefully consider the system as a whole incorporating your generator into the mix; in the beginning you may need to rely on it a lot.  For instance, most of the smaller (and cheaper) inverters out there have no charging capabilities, and so you would need a separate charger to charge the batteries from your generator, but there are some inverters out there that are able to take AC power and charge DC batteries (the larger ones can put out quite a large, rapid charge).  Worth considering, and figuring out how much you would need to run the generator with various set ups... particularly considering the price of fuel.
I'm sorry but you left me confused regarding your comparison of series vs parallel; but basically they produce the same amount of "power" in watts, the difference is that by adding in series you up the voltage while the current (amps) remain the same, by adding in parallel you up the current while the voltage stays the same.  Not sure if that helps, or was redundant...
hopefully it gets you started, and that should produce further and further questions...

Re: Adding batteries (this easy?)

Adding panels is easy, adding batteries is more problematic, as describe elsewhere.
We live with 150 watts of panel, 750amphours of battery, a xantrex tc 20 charger, morningstar 300 sw inverter, Honda eu1000 generator, tri-metric meter. We live full time, pump water with gasoline and refridgerate with propane. We use about 25amp/hours/day, the system charges at about 10-12 amps average. We save the big load items, (charging the lap top for example) for either full sun days, or wait until we have to run the generator to top up. Most days we get to 100% by about noon.

We run satellite internet, radio, 2 pc's printers etc. (No tv). cfl bulbs, Automobile radio with ipod. Over time, our loads continue to grow as the convience of having ac all the time. I would go with a bigger battery bank early and add panels as needed, rather than the other way around.

Icarus

Re: Adding batteries (this easy?)

dsun1,

In addition to what others have said, consider purchasing a Kill-A-Watt meter. It will help you decide in advance how much power you'll need, and in making decisions regarding the replacement of devices that use excessive energy.

I think you might benefit from reading about my experiences with a small off-grid PV system. Check my blog: http://solarjohn.blogspot.com

SJ

Re: Adding batteries (this easy?)

that is basically getting it to 80-90% of the charge without topping it off to 100% with the absorb charge.