100 watt Thunderbolt solar kit defective or user error?

[Makillyah]

Hey y’all! I recently got the 100 watt thunderbolt solar kit from harbor freight. I know it’s not the ideal system but I decided to go for it because someone I know has it for similar use as I intend and it worked great for them. It’s a low price point and will work for now… or will it? So here’s what’s happening: it charges great in full sun, maybe even low sun light, but if it’s too overcast or I leave the panels plugged in after the sunsets it discharges quickly (without anything being plugged in) like way faster than actually using it for lights or anything. If I unplug the panels it’s fine, no change. What is going on? I’ve checked the connections, they seem fine, it’s a super simple plug and play system so I don’t know what I could be doing wrong. If the panels are defective I still have time to exchange them, I just want to rule out user error or if that’s just how these panels are then I’ll return them and go for something else instead. Wish I had my friends number to ask but I only see them once a year. Thanks!

 

[Bobert]

Are you using a charge controller?

 

[rmaddy]

This one?

100 Watt Amorphous Solar Panel Kit

Amazing deals on this 100 Watt Solar Panel Kit at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

My first thought was that some panels can actually pull power from the battery at night but this one has the following bullet item:

Blocking diode prevents panels from discharging your battery at night

So perhaps you have a defective panel. If your friend doesn't have this issue then I would exchange yours while you can.

 

[Bobert]

If you have the setup with 4 panels you can find out if one is pad by unplugging one at a time. I suspect the charge controller is the problem.

 

[time2roll]

100 watts is a small charging current. Is the battery getting fully charged to 14.5 volts? When the sun goes down the battery should rest fully charged at about 12.7 volts. That drop is not an indication of discharge. Just settling off the surface charge.

I assume this is charging a flooded lead-acid battery.

 

[Planecrazy]

I have this system just to provide lights in a detached shed, it was my introduction to solar power. I use the Harbor Freight 35AH agm battery and there is no problem with discharging at night or overcast conditions. I think you have a faulty panel.

 

[Bud Martin]

Do you have clamp-on DC Amp meter or use DC Amp meter that you can put in series with the panel to see how much current the panel/panels are drawing the current from the batteries at night?