200 watt panels to Battery AH ?

Kevin10873

I have two 100 watt panels and will run them through a MPPT controller. I would like to know how big a battery do I need. I will be using the batteries as 12 volt without an inverter for a just in case the grid is hacked. I may run a small 12 volt TV or a 12 Volt scanner. I was thinking a 100 AH AGM would work; what do you think?

Photowhit

That should be about perfect, 2 100 watt panels should reliable produce about 10-12 amps in the charging range for a 12 volt battery bank, or about 10-12 % of a 100 amp battery bank. That's in the range of 10-13% we like to recommend.

If you are buying an inexpensive MPPT type charge controller, you should check to see that it really is an MPPT type! also the panels should be run in series for best results.

Kevin10873

Thanks Photowit; I purchased a EPEVER MPPT Tracer A series controller with a MT 50 remote meter.

mcgivor

The EPever is supposed to be a reasonable product, being a true MPPT controller. The battery capacity should be calculated by the loads and what they draw, amps multiplied by hours, remember a 100Ah battery has a usable capacity of 50Ah maximum, for longer life expectancy, less depletion is better. Have these calculations been done as it appears, from the outside at least, that this is a reverse engineered system, based on the question, don't want to see fundemental mistakes made, that's all.

littleharbor2

For a beginner you might want to consider a couple 6 volt FLA golf cart batteries. They are inexpensive and will give you around 200 - 220 amp hours. A scanner sounds like something you would keep on continuously, probably more than a single 100 ah. battery can handle. That being said  and if this is going to be an everyday system you would want to add more charging power. Rule of thumb is 10% of your ah capacity for charging amperage in a daily use system.  which, in this case would be somewhere in the 20 - 22 amps of charging power. a third 100 watt panel should get you there.