Solar on a cloudy winter day?

[mtnbbud]

I recently got a deal on a suitcase style 120 watt system with a 20 amp controller. I wanted to test it so I hooked it up and attached it to my old trolling motor battery. The controller indicates it's charging at 12 volts and 0.8 amps.

Is 0.8 amps going to do anything? When attaching this to my rv batteries, is there a minimum amps I should be looking for before charging?

I have two Trojan T105s at 225 amp hours. I thought this panel could help keep my batteries topped off when dry camping.

Thanks Jeff

[pianotuna]

Hi Mex,

I've been doing cod liver oil for my aches and pains. It works well for me--but doesn't work for everyone.

[MEXICOWANDERER]

I found a Russian military style hat with flaps covering the ears made a huge warmth difference. Furry polyester lined. I cannot over empathize huge.

For the 1st time in 11 years I am minus elbow, hand and shoulder pain at night that forced me to keep the things uncovered. How? The only thing different since May is Vitamin D3. Sounds nuts but I'm pain free and with a warm head sleeping much better. Now if I can reduce middle of the night freeze butt bathroom runs ..

[MrWizard]

My heater runs at night as needed,
Blankets are good, but if my head gets cold I end up sick,
Of course Southern Calif is Not cold country, last night was 44°F
Jan & Feb is when the temps can drop into the low 30's high 20's

[mtnbbud]

Thanks for all the replies. I appreciate it!

[steveh27]

I also have a 120 watt suitcase portable. I use it in FL when boondocking as a snowbird (not this year). It has worked well for me as I use only about 35 AH per day. I have gotten close to 7 amps out of it at peak. I like being able to park in the shade & put the panel in the sun. Fortunately I have not run into cloudy days down there.

My battery was only 105 AH which I have replaced with 2 100 AH Lifepo4 batteries. Can't wait to use them. I am thinking of adding another portable panel.

[3_tons]

For my own back of the envelope trip estimations I figure on capturing about 70% of panel wattage rating overall on average or about 50% or less in less than optimal conditions, but these numbers are mostly just for planning purposes... Season and latitude plays a roll...

440w of solar and one 200a/hr LiFePo4 beneath the dinette seat...

3 tons

[ajriding]

Best to wait for sun and see what happens before thinking too much.

In the sumer with sun your 120 watts should be plenty to keep things topped off. It all just depends, but for light use you are good.
In winter when days are short, the sun low and many cloudy days then at best the panels will be good for keeping batts topped off for storage (not for daily use). But it all depends.

You said "folding" so this is a portable system...
How long is the wire going from panel to the battery?
How heavy a gauge is the wire?
Where is the controller located in that wire (close to panel or close to batt)?

I assume with folding/portable that you are pointing it to the sun, correct?

Yes, the furnace fan is a power hog. If it is a cold night and with good batts that might be all you want to power up after about 3 pm in the afternoon. Good idea to change habits. some ppl heat the cabin when they are up and about in the evening, then turn off furnace and just get under the blanket, then turn it back on right before the alarm goes off.

[pianotuna]

Hi,

I get 7 amps in leafy shade. Harvest is 3 amps in heavy rain at solar noon.

[Lwiddis]

Voltage is the pressure of electricity. As with water, if your pressure is inadequate, no water...or power...will be pushed into the “tank.”

[Lwiddis]

If your solar panels are really putting out only 12 volts, nothing will get in to your battery unless you are below a 40% SOC. Bulk charging, for instance, for two Trojan T105s should be 14.7 volts. Pressure pushes power into a battery. See...

https://www.trojanbattery.com/tech-support/battery-maintenance/

[MEXICOWANDERER]

Ktmrfs
Nearly identical % on a cloudy day. PANELS USELESS. Down here dark overcast may last a week just as charging is needed most for lights and fans. This is where a 2 Stroke Harbor Fright gen and Megawatt excel. 40 amps. California governor is threatening to ban generators. The man has inhaled and held it too long.

[BFL13]

deleted

[mtnbbud]

[ktmrfs]

I have 480W of portable solar. Cloud cover cuts output considerably, and very dense heavy cloud cover even with the panels aimed well has cut the output from 30A the controller limits to down to 5A or less.

How much it affects output is very dependent on how dense the cloud layer is. But expect at least a 50% decrease in output.