12V Battery Question Please
 

I recently decided that I wanted to delve into the world of solar energy. Ultimately, I would like to have our home totally off the grid, however, one has to start somewhere. I live in Salisbury, MD 21804 and gave myself a budget of $450 to assemble a portable setup to use on my deck and in the even of a power outage. Please be advised that I am by no means an expert and I have little experince with things electrical. I do follow directions well and am handy around the house. I spent hours and hours reseraching, watching YouTube videos and reading articles on this subject.

I purchased this panel from eco-worthy.com: 100W (2*50W) 12V folding mono solar panel with 15A solar charge controller:



I also purchased a GT Power Watt Meter and Power Bright 1100 Watt AC DC Inverter.

I probably put the wagon in front of the horse but I purchased a battery today and this is the only part of this system that I'm not sure of. I purchased a Deka Batteries EPM DC27 with these specs: 715ca, 200m@23a90ah cycle. Do you guys think this battery will be OK with my setup? Any help or suggestins would be greatly apprciated. BTW, I came in over budget at $510 including a $13 core charge on the battery :-)

Thank You,
Ed

Fantastic! Great little set up to learn with. It has its limitations but with that GT Power Watt Meter handy, you'll learn what you can do with it..

I researched the battery and it has ~100 aHr. of reserve. If you're careful and don't drain the battery any less than 25% of its total rating, you'll get the longest amount of service from it. (25 aHr. Maximum) That Power Watt Meter will help you keep an eye on the usage..

Keep in mind that the inverter can/will eat the battery up really fast! It's a 10 to 1 ratio. It takes 10 amps of the 12 volt battery to make 1 amp of 120 V.A.C.

Congrats and have fun learning!

giving that more battery storage

you should match your battery storage closer to your panels output level or you will be forced to burn off or use the excess power as its being produced , and that may be wasteful.
if your not using your panel to its full ability that should be rectified as part of your education before you move on.

my guess is 4-6 batteries.

Thank you very much

I thought that I would relate some of the specs of the solar panel (2 50W in series)

Related Power 100W
Vop = 17.9V
Working Current (lop) = 5.59A
Output Tolerance = +/-3%

some links that will help understand it and size it

Sizing batteries and inverters for a solar PV system | Bijli Bachao


and here from Trojan batteries (the maker of golf cart batteries etc.) is a battery bank calculator

Trojan Battery Company | battery capacity calculator

Check Craigslist and you might be able to find some used golf cart batteries, 2 or 4 of these 6v batteries will give you many years of useful life, the shallower discharge rates are much better for the batteries.
The larger batteries will also give you a much longer reserve, your system is so small that a large battery bank is not going to take up that much space, unless you plan on putting all of this on wheels and hauling it around.

Battery Sizing
 

Working Current (lop) = 5.59A Round that to 5 amps. (Nothing's perfect)

Design for the worst.. December. You will average ~2 hrs. of charge time. In great conditions, panels angled correctly, you'll collect ~10 aHr. max. at the battery..

This amount also dictates your usage. If you use more than you collect, you'll ruin the battery over time. This will vary with current weather conditions. The goal is to keep your usage at or less than you collect in a day..

During June, you should be able to collect at least 25 aHr. (5 hr. prime charge time) I'd say that's about the maximum to be expected with 100 watts of panel. That equals to 25% of the capacity of the battery that you now have, which limits your usage to 25 aHr. I'd say that's a good balance. You could go with more battery but remember, it will take more time to charge. If you discharge it more than you can collect, it could take days to bring it back to full without using the system for anything. It could become a vicious cycle..

UPDATE

My panels arrived yesterday and I wanted to test my setup today. The charge controller green light is on. In fact, it was on when I opened the box and that seemed strange to me. Any, I inserted a Watt meter inline between the battery connections on the charge controller. The source side is to the battery and the load side is to the battery connections on the charge controller. I also have an 1100 watt AC DC inverter attached to the battery. The watt meter is not registering anything to do with amps even with a 110 device plugged into the inverter. How can I tell if the solar panels are actually charging the battery? The watt meter is only registering the actual battery voltage. Thank you very much.

I think if you use a multimeter on amp setting you can read the amps the panels are putting out then x that by the volts , which will give you the watts.

are you using a dc watt meter
is the battery charging or fully charged
try drawing power to see if you get a reading and last but most important is the watt meter wired correctly, and the right buttons pressed..

Here is a dc watt meter for instance

Attachment 4236

The source side is to the battery and the load side is to the battery connections on the charge controller.

I believe that you have it connected backwards. You're source will be the charge controller and the load will be your battery. Connected in this fashion will tell you how much charge you are getting to the battery..

If you plan to monitor your load from the battery to whatever, the unit needs to be installed between the battery (Source) and the item you want to monitor. (Load)

"Source" (in) "Load" (out)

Quote..
You can think of the Watt Meter as a set of jumper wires. Connect it in the same way and you can measure what the jumper wires are connected to. Like jumper wires, the Watt Meter is essentially a direct connection between same colored SOURCE and LOAD wires, i.e. both the SOURCE and LOAD leads are electrically “hot” when a battery is connected to either side. Current flows from SOURCE to LOAD. Make sure connections are secure to prevent component damage!

http://www.vshopu.com/item/2118-0803/GTP-wattmeter.pdf

Is your solar controller an MPPT version? These convert higher voltage input to lower output voltage, but with more amps, which is very useful for charging batteries. Your 100 watt panels make 100 watts at 17 volts, but a fully charged 12 volt battery is only 14.5 volts (float at 13.8v), so, at 14.5 volts x 5 amps (your panels maximum current), your only putting roughly 72 watts out. An MPPT on ebay like this 30A MPPT Solar Panel Regulator Battery Charger Controller 12V/24V With LCD USB | eBay is well worth the cost. I have 1920 watts of solar, with a peak output of 60 volts at 32 amps, charging my 48 volt system. The controller uses the maximum panel voltage (74 volts) to charge the batteries at a much higher current than without. My WattsUp meter has recorded a 28% increase in power extracted. Well worth the money.