SOLPERK 20W Solar Panel，12V Solar Panel Charger Kit+8A Controller， Suitable for Automotive, Motorcycle, Boat, ATV, Marine, RV, Trailer, Powersports, Snowmobile etc. Various 12V Batteries. (20W Solar

Before writing this review, I had decided to wait awhile until I generated about a half a kilowatt of power with this 20W panel. This took about two weeks of clear/cloudy days, relatively equal in number, thankfully, especially for the purposes of testing.I'll begin by giving this product 5 stars right off the bat, out of fairness. You'll see why I rated it lower later on in the review. To begin, the panel arrived with questionably adequate padding, but was substantial enough to not have any damage whatsoever. Not removing a star for this. The panel itself is of expected quality, your average polycrystalline panel, with decent glass and a solid aluminum frame. Zero complaints on the quality of the panel; however, there is a small amount of rust that began propagating on the stand arm. This might have been my fault, and rust is extremely easy to fix, so this does not concern me.The charge controller is something that intrigued me before buying, but decided to give it a chance. This is where my complaints begin.The controller reads a max output of 8 amps, which is physically impossible to max out with a panel this size, as the 20w panel it comes with will produce no more than about 1.2 amps. the fact that it is advertised in large font on the face of the controller is potentially misleading to customers that do not understand the fundamentals of how these systems work. This just means that the circuitry in the controller can handle UP TO 8 amps, NOT PRODUCE 8 amps of current. I knew this going in. Not going to remove a star for this, however. Wouldn't be fair.I'd like to re-clarify before jumping into the problems of the controller that this is a MAINTAINER controller, not a dedicated battery charger. Understandably, you wouldn't really expect to fully charge a large car battery with something like this, but surprisingly enough, 20w is enough to fully charge your standard AGM battery from a minimum low voltage of 11.8v to a full 14.2 in about a day or a day and a half. The only problem is, the controller isn't even designed to charge your battery, just maintain it.This is where the biggest problem of the controller comes in. The cut-in voltage (as advertised) is 13 volts. This is a problem because like many batteries, the storage voltage fluctuates depending on the temperature. Where I am in Canada, a fully charged battery can dip below 13 volts easily even well above freezing temperatures, meaning that the charge controller supplied with this package simply will refuse to maintain the battery until it reads a voltage higher than 13 volts. Removing one star for this. There's literally no need to have a cut in voltage above the minimum battery voltage, especially when this panel is already capable of charging the battery to full, from "dead".Secondly, when I began testing the controller in an indoor, isolated environment (for science), it wouldn't even bring the battery up to the advertised full charge voltage of 14.2 volts. it would stop at about 13.5 and would only resume charging when disconnecting and reconnecting the PV panel, then the terminals, then reconnecting the terminals, and then the PV panel again (the sequence is important to prevent damage to the controller). Only then would it resume charging. Removing another star for this, as you would expect, you shouldn't need to intervene just to get it to work properly. To make sure this wasn't just a glitch, I discharged the battery a bit 3 times, still with the same issue.Because I had anticipated this controller might be problematic, I had also bought a Renogy Voyager controller to compare them side by side. I was extremely surprised to find that the included controller was only ever outputting 0.9 amps into the battery, yet when the panel was connected to the Renogy controller, would output the advertised amperage of 1.2. To test this, I made sure do it on a fully clear day, where maximum power generation was extremely consistent. I honestly could not understand the reasoning behind why the amperage output was lower on the included controller, and gave up trying to understand until I eventually dismantle it. I guess I'll remove another star, now at 2 stars, but I feel a bit guilty about this, so I'll look back into the positives.Aside from the controller that I replaced with a far more useful one, this panel actually performs very well when hooked up to a proper controller. It ACTUALLY WILL CHARGE A BATTERY FROM EMPTY (11.8v to 14.2v) if you do connect it to a better controller. Like I said earlier, it takes about 1 or 1.5 days to fully charge my single AGM car battery from its "dead voltage" (I use an optima yellowtop rated for 55ah, but realistically only about 45ah of usable power). The panel is nice, so I'm adding a star back. This concludes at three stars. If the price was lower, I'd give it another star. If the maintainer controller didn't cut in at such an unreasonably high voltage, I would give it another star. As far as the amperage output of the included controller goes, It probably isn't a huge issue for the customer it works well for, as again, it is designed to be a maintainer.All in all, I'm not really disappointed in this at all. I found a good use for it and it is compact enough to prop up whenever I need it.A little too little for a little too much, but satisfactory nonetheless. Maybe my controller was just a dud, like some other reviews. I'll have to dismantle and test every component to be sure, but for the sake of this review, I didn't prioritize it.

nothing to not like, this solar panel is easy to use and keeps our lawn tractor charged up, very pleased

Used this product on the roof of my bike trailer to provide charging to an internal car battery that powered the 12v lighting system as well as the trickle charger for the bike battery. Works very well.

It does not move from charging or goes out totally and no charge at all.

Updated .... I did update it to five stars because I absolutely love the solar panel and the seller after ensuring my controller was not functioning properly sent me a new one free of charge with extremely quick delivery thank you so much to the seller and it's a great product ..First reviewI really would like to give a 5 star but the controller that came with the panel does not have and volts coming through it.. I get 18 volts with a meter at the end of the wires from panel but when connect it to the solar panel side and connect the clips the is no volts reaching the attached battery.. so I disconnected the clamps and tested the wires out of controller on battery side and no power... I had another controller from another system and when I connected it to the panel it had 13.8 v coming thru it to the battery clips..I found out the issue after having it (supposedly charging the house battery on my rv in storage and I went to ch3ck on it and it was at 3.8 v.. hopefully I can get it to fulling change and hold a charge or I will be out not only cost of having to buy a new controller ( hopefully vendor/seller will send me a functioning controller) but also a new house battery.