House/solar battery opinions

[seraphim]

My current battery space is 20"L x 14"w x 10"H

Going solar, and want to packs as much AH in there as I can (reasonably). Currently looking at 250 - 300. Price is not THE deciding factor, unless all else is equal.

I don't have experience with a lot of different companies, so I don't know who may a poor reputation. Some I am looking at:


http://www.apexbattery.com/group-8d-gel-solar-battery-solar-batteries.html $609 + $109 shipping)

http://www.atbatt.com/product/23216/sla/power-sonic/12v-150ah/battery#tabs ($774 for 300ah no nipping)

http://www.batterygiant.com/Product/8D%2DGEL (allegedly $577 (maybe $669) for 225AH can pick up locally)

http://www.mastervolt.com/marine/products/agm-slimline-12v/agm-sl-12-150/#specifications (can fit 2 185AH units in my space - haven't found an online price yet, which tells me something lol)

Any thoughts on these, or others you are aware of?

[full_mosey]

seraphim wrote:
As in 17.7 / 48c equals ...

I don't understand!

What I was saying is if the coefficients are expressed in % per C and the calculator wants V per C, you need to convert % to V.

-0.385% of 17.7V = -0.068145V.

The calculator needs -0.068145V, not -0.385%.

HTH;
John

[seraphim]

As in 17.7 / 48c equals ...

[full_mosey]

seraphim wrote:
.0385

Thanks John. I figured the coefficient I entered was wrong somehow. I just had no visible guideline.

Started wondering if I couldn't pack more on top ifI conserved using smaller wattage panels. Found a 50 watt 24v panel ($100 each) and I could conceivably squeeze 14 to 16 panels on top lol. Haven't run the numbers yet..

Is that coefficient a %, as in -.385%/C? giving 17.7V * -.00385 = -.068145V/C .

IOW, up 1C would be 17.63V.

HTH;
John

[seraphim]

.0385

Thanks John. I figured the coefficient I entered was wrong somehow. I just had no visible guideline.

Started wondering if I couldn't pack more on top ifI conserved using smaller wattage panels. Found a 50 watt 24v panel ($100 each) and I could conceivably squeeze 14 to 16 panels on top lol. Haven't run the numbers yet..

[Almot]

seraphim wrote:
Still working on that calculator. Doesn't like the AM solar panels. Get an insufficient voltage in the array, unless I use an Mppt, then I seem to need a minimum of 7 panels lol

1) There can be no "insufficient voltage" with multiple panels of 12V nominal and 12V bank, if wires are adequate. But you do need MPPT for 12V in series.

2) There is no minimum panels number or minimum panels wattage with MPPT. The only "minimum" parameter for MPPT is the voltage - Vmp should not be lower than the bank nominal votalge, 12V in your case. 4*100W in series will provide around 22 Vmp, enough for MPPT.

[full_mosey]

Try -0.00385
I had to type "-.00385" without the leading 0 before the decimal.

HTH;
John

[full_mosey]

seraphim wrote:

Without mppt

Figured the coefficient myself. Accurate? Idk

This one is saying that 10.77V is too low to meet the battery charge settings.

Something is amiss.

[full_mosey]

seraphim wrote:
Must have done something right this time with mppt

Without mppt

Figured the coefficient myself. Accurate? Idk

Are you sure the Nominal Operating Cell Temperature is 48C. That is way hot. Try an NOCT between Record Low and Average high Temperature. Also set the low lower. 15C is 60F. You are going to camp below 60F!

Is there a link to this panel?

OK, I have looked at the sunelec.com site and found 20 and 45C on two different panels. There could be a bug in the string calculator because 48C seems like a reasonable temp. I know my panels get too hot to touch.

I changed the Low and Average temp to 0 and 55C and got this:

ERROR: The TriStar-MPPT-60 MPPT controller is not compatible with this module.

HTH;
John

[seraphim]

Must have done something right this time with mppt

Without mppt

Figured the coefficient myself. Accurate? Idk

[seraphim]

I wondered.

Still working on that calculator. Doesn't like the AM solar panels. Get an insufficient voltage in the array, unless I use an Mppt, then I seem to need a minimum of 7 panels lol

[pianotuna]

Hi seraphim,

I don't like the handybob site. Too much chaff and more than a few misleading ideas.

[seraphim]

Don yea, I've got that site bookmarked. There was another one by HandyBob I need to find again. He claims to be a trouble shooter for RV solar systems and had some interesting observations about why some systems failed and others worked.

Not sure of his bona fides, though

Here's the link

[seraphim]

John

Thanks for the example - now I know what I'm looking for with calculator.

It was interesting to change the controllers, and watch the results as well.

[pianotuna]

Hi seraphim,

I find this link pretty much says it all with the exception of balanced wiring for battery banks. It is a tiny bit dated. http://www.jackdanmayer.com/rv_electrical_and_solar.htm#The%20Golden%20Rules