SUNER POWER 12V Solar Panel Kit 20W, High Efficiency 20 Watt Solar Panel + Ultra-Smart 10A MPPT Charge Controller, Solar Battery Trickle Charger Maintainer for Boat Car RV Motorcycle Marine Automotive

I use mine to charge the lead-acid battery on a 16 ft gate opening system. It's fully exposed to the weather and has been through several ice storms and hail storms and it keeps on working. It is shaded during different parts of the day and I have had no issues with the battery charge level.

I got the panel, put as meter on it, got 19.87 volts. Controller connected, yellow light came on (no explanation in the minimal paper work what that meant) Output of the controller was only 4.3 volts! Connected to a battery to charge, light went out. Multiple emails sent to company (they have no phone!!!) went unanswered to after five days. Item returned to Amazon.Amazon refunded my money the day UPS got the package which is excellent, though the money was put in an Amazon 'gift card' and not refunded to my credit card.Edit: 12/7/2019 - The company reached out to me after the return was completed. They sincerely wanted to make things right. They sent (at no charge) a 20 watt panel/controller kit and asked if I'd re-review. I agreed. The kit arrived yesterday. I set it up temporarily, being extra careful to follow the directions. They are not written by an American and therefore, loose something in translation unfortunately.The battery I used was a little low, 12.6V. I attached the controller to the battery FIRST and then the panel to the controller per the instructions. I rechecked the voltage at the battery and got 12.73V, which means it is charging. The was at 11:30AM with a winter sun (low on the horizon, panel vertical and not optimally positioned). So it works. I'd like to see the voltage rise further and will recheck tomorrow and the next day. Ideally, it will be in the 13V range indicating a full battery on a float charge. I will also check for a precipitous drop in battery voltage (the blocking diodes should prevent this) after cloudy days.To use to charge a item like my tractor, it seems I have to disconnect the panel from the controller and then disconnect the tractor from the controller. Not particularly convenient. I would think you could leave it connected to the controller all the time being careful (read being responsible) not to short the output.I suspect my problem with the first panel kit was a bad controller as only one LED lit and it was a faint yellow. All LEDs light now as expected. I have changed my rating from one star to four. If we hit 13V after a day of sun and no drop in voltage after a cloudy day, I'll bump it up another star!Edit2: 12/18/2019 Suner was disappointed I could not make a better review and they (Mason) was committed to doing right. Seems the controller I got was bad and the new one, worked as expected. The paperwork with the panel is not clear, a problem in technical writing from China to the US. Also, an email sent is responded to most likely while you are in bed at night, so it can be a drawn out process to resolve issues. But I can assure you, they will take care of you. Patience. My battery now has a full charge (13.7 volts float) in mediocre sun.Here are the key concepts. The battery must be somewhat charged, 11.5 volts or better (less is essentially a dead battery). You must connect the battery first. Doing so, the controller 'figures out' the battery voltage (12 or 24). After a few seconds (two lights will come on), the lights change and you can connect the panel. Then after a few seconds, all three lights will come on. You are in business! If you disconnect the battery (like I do, it is maintaining a tractor) you must follow the procedure. Controller disconnected from EVERYTHING. Connect the battery, wait for two lights, , connect the panel, all three will light. Suner earned the five stars!

"Installed easily and works as described. It's on my garden shed right now!"The above, was my original review, and I gave it five stars. Not so much now.The controller began showing some anomalies early on, although I couldn't identify whether it was inadequate storage giving me the problem or something else. Now it appears that it is indeed something else: it looks like the controller has failed.I have attempted to contact SUNER, but when I did send them an email describing the problem, the site immediately went back to the Home page and gave me no indication as to whether the email sent to the Technical Support group actually went through. So, since I had kept a copy of the email describing my problem, I immediately tried sending the same message to Customer Service. Only problem was that when I tried to connect to that link, I immediately got a 404 response. I logged off, shut down my browser, re-initiated another browser, went back to SUNER support and tried to contact Technical Support: 404. Same with every support link on their site. Not real happy with my purchase right now, but I'll give them a couple of days before buying another controller (from someone else).The above response to a controller that likely failed was filed yesterday as "I originally thought highly of this product, but..." with a three star rating. Less than 24 hours later, SUNER Customer Service responded and agreed that the controller had failed. They requested my order id# and said they would immediately send out a replacement controller. They are definitely back up to four stars in my book, and if I get the replacement controller in a reasonable period of time, they'll be back up to five! Good job SUNER Customer Service!