I know a little about electricity, but I'm not an expert nor an electrician.

I've bought 3 30W 12V small solar panels, a cheap "chinese" controller and have a spare 12V car battery and a 110V inverter.

The controller has only 1 place to hook up solar panels, but I have 3 panels. I know parallel means increased amperage and serial means increased voltage.

I plan to hook up all 3 parallel to the 1 spot to have more power input to charge the battery.

The question I have is how to ensure that the solar panels push power to the battery and not each other? Do I need some sort of fuse or resister in each inbound line from each solar panel to ensure the power only goes 1 direction? If so, what do I use and where do I get it?

I can do some minor soldering, have a cheap wand solder thingy and a cheap volt meter, so I know I can build it up but I want to make sure the 3 30W panels are pushing into the battery and not into each other.

Any help would be appreciated.

PS This is more just to play with and not to "power a whole house" or be off-grid. Just something in case we lose power here for a bit more than a few hours... like being able to open the garage door LOL.

James

I'm working on a Tuff shed garage that will be solar powered.

I don't think you have to worry about "pushing" power to the other panels. Your parallel connections goes from the panels, to the charge controller, to the battery.

The charge controller will prevent current flowing back to the panels.

CAUTION: Solar Power hobbies have been known to cause mass confusion and a wallet content siphoning effect! You have been warned BEFORE you have gone down the rabbit hole



I found a guy on YouTube who opened his garage door with a Goal 0 Yeti 1250. It used 312 watts during operation. https://www.youtube.com/watch?v=JqlKijjQn-A

I like to visit the Solar Panel Talk forum. It's got lots of valuable information. I don't know the rules of the Sigforum, regarding posting other forum links, so you'll need to google-fu it.

Have fun and good luck!!!

If you wire parallel and one panel is shaded or partially shaded or blocked it will not pull down the entire system.
Each panel should be fused.

quote:

Originally posted by armored:
If you wire parallel and one panel is shaded or partially shaded or blocked it will not pull down the entire system.
Each panel should be fused.

Fused before going to the controller? I can do that.

James

quote:

Originally posted by armored:
If you wire parallel and one panel is shaded or partially shaded or blocked it will not pull down the entire system.
Each panel should be fused.

Fused?? Tell me more please, I've had my panels (4) up for quite some time, going to a charge controller and into 6 solar batteries. At the time, no mention of fusing the panels. I ask just for the possibility of an EMP. I worry about whether or not an EMP could cause a fire.

quote:

Originally posted by wreckdiver:

quote:

Originally posted by armored:
If you wire parallel and one panel is shaded or partially shaded or blocked it will not pull down the entire system.
Each panel should be fused.

Fused?? Tell me more please, I've had my panels (4) up for quite some time, going to a charge controller and into 6 solar batteries. At the time, no mention of fusing the panels. I ask just for the possibility of an EMP. I worry about whether or not an EMP could cause a fire.

Adding fuses or a circuit breaker after the panels and before the controller is easy ,cheap protection. It also enables you to isolate a bad panel or panels by simply pulling a fuse.
https://baymarinesupply.com/wi...-atc-fuse-block.html

James, what is the capacity in watts of the controller? Most of these I have seen are designed for a certain size solar panel, usually in a little kit. If the controller will handle an input of 90 watts then you can parallel the 3 30w solar panels.
Otherwise you could parallel the output of 3 30 watt controllers to the battery. Do not know how well this would work, never having tried this.
You may need to use heavier wire in these parallel circuits.

Cheap 10amp 12/24v controller from ebay from china. In the ad, the say the controller can handle something like 120 watts

James sounds like that should work fine. I would think part of the controllers job is to prevent draining the battery back thru the solar panels when they are not charging. i.e. after dark, cloudy days.
Power flows from a higher voltage to a lower voltage. If the solar panels have the same output in voltage then no flow between them, only to a lower voltage usually the battery. When the battery is charged then the controller shuts off flow. A bad solar panel can drag down the output voltage of the solar panel array.

A properly rated diode (installed in the correct direction/orientation) would ensure that power only flows in one direction... The following link looks to describe your scenario and they do use a diode on each panel to prevent one panel from dragging the others down.

https://www.mpptsolar.com/en/s...els-in-parallel.html

sreding is correct.
Some solar panels designed for array use already have a blocking diode installed. Need to check inside the small junction box on the back. Or mfg. literature.