Morningstar SunSaver 10A PWM Solar Charge Controller - 12V/24V Battery Compatible with Low Voltage Disconnect (LVD) - Reliable Solar Panel Controller for RV, Boat, Off-Grid & Home Solar Systems - High Efficiency with Industry-Leading Low Failure Rate

The newest model has addressed the float point problem mentioned in this review. New Sunsaver Models have a float voltage of 13.7.July 31 2015. Sunsaver 10 and batteries still working. Batteries deserve a mention -2 Optima large yellows. Have also bought a morningstar mppt15, and added some panels. In my case the mppt did not show a huge difference, and i monitored it every day (digital watt meters on both systems) compared to the ss10.I am running both controllers in parallel into the same battery pack. IMHO a small system could be better upgraded ,by adding an other panel(s) and another ss controller instead the expense of the mppt. I'm now using a 110 volt freezer (run as a fridge). Freezer run by "Tiger Claw" pure sine wave inverter.May 19 , 2013 update. Same panels, same batteries, same charger. All is well. Fridge died , but controller is still doing the job.If you battery(s) are worth more than $25 this is probably the best cheapest controller. If you buy a cheap controller, you need to check what is happening with a volt meter. The cheap ebay controllers i tested are not good.2 years ago-This is an update after 5 months of constant use in Baja california. I run a 12volt refer and the lights to a small house.Testing with a watt meter:Watt meter between charger and battery. my panels( 3- 20 year old 50 watt panels) had at least a peak wattage of 130 (9.5 amps) watt on a sunny day, and hit 200 watts on some partly cloudy days. So the unit was pushed to the max, and held up well. Wattage to a fully charged battery was 5-8 watts. There was no heat coming from the unit. Would up my rating 5 stars. Therefore the following review should be changed in spots, but I'll leave it for now.How Morningstar Sunsaver ss-10 works and the potential flaw.Assuming temperature 25 degrees C: the controller will put a voltage of 14.4v into the battery. With no load on the system, and sun, a voltmeter will always read 14.4v no matter what state of charge the battery is in. This is just what my battery type wants- constant voltage. So far great.But when the battery is fully charged , the float voltage does not go down to around 13.7v. The float voltage is 14.4v. After 2 days of charging, an analog amp meter shows zero current going into the battery. however my 0-25a meter is accurate at best to + - 1 amp. So maybe a float voltage of 14.4v is ok? Provided the current is very low. My batteries (expensive) call for a float votage of 13.2v to 13.7v. I'll know more when I get a digital amp meter.I can't find any specs from Morningstar on how much current is going into a fully charged battery.It's just sort of dissapointing that I spent the extra money for a name brand, and may have ended up with an inferior product. If I had known the float voltage was 14.4v, I would not have purchased. Especially with no specs on current at the float voltage. If I hadn't modified the mounting holes , I would return it. Now I'm left with the problem of finding out the current myself, and then babysitting the thing so my batteries don't overcharge.The temperature sensor works well.Correction. I started out with an 85% charged battery. I do not know what the initial charging battery voltage would be if I had started out with a more discharged battery. Probably would depend on % battery charge and output of solar panels. Float voltage still 14.4v.Update. I bought a 10 amp controller that looks identical to the HQRP 10a. Was not purchased from amazon. Was 20 bones delivered.That controller is way way worse than the sunsaver. It starts the day on a fully charged battery and enters an equilization phase. Battery voltage is brought up to16 plus volts then shut off until voltage goes down to 14.4v. Then the full power of the panels ( 6 amps in my case)is put into the battery until voltage goes to 16 plus again. This went on for an hour until I pulled its plug. Next day same thing. I'm not sure what kind of battery likes this treatment. Not gel and not my AGM. Would be ok for an old car battery you don't care about. So for under 60 bucks the morningstar may be as good as you can get. I've put a switch on the morningstar and can lower the float voltage to 14.1v. I think I can live with that. Or maybe go back to the nc25a I was using. I have no use for the load contols on these controllers. I'm not lighting a street lamp. My main use is running a fridge/freezer, that shuts down when batteries are below 12 volts. I would be happy if the manufacture left out the load feature and just spent the savings to make a charger that correctly charged the battery.I like that it has lights that display the battery charge state as well as a status light showing solar statusI have a garden away from the house that is too far to run electricity. I needed an electric fence to keep the critters out and a pump to bring the water in. I have several solar panels a friend gave me so I decided to make my own little solar power set up. I ordered one of those cheap Chinese made charge controllers to save a few bucks. Well, that was a mistake. The thing was DOA and looked like a piece of junk. The instructions were in Chinglish.I decided I needed a better controller so I did a little research and came upon the SunSaver on a sailing website. I figured if it could stand up to the salt water, it could take the weather and would be reliable. Since it was cheaper to order through Amazon, I ordered it here. It's hooked to three 40 watt panels that put out 7.5 amps. I have a deep cycle battery that it charges. There's a 12 volt fence charger hooked to the battery and a 12 volt water pump that I hook to the battery when I need to water. I installed it a month ago and it is working just fine.I would urge anyone who is looking for a solar charger to pay the extra few bucks and get a well built, quality product like the SunSaver. It's worth it.Update: It's Spring now and my controller is still working. It was hooked up all Winter with temps down to -37F and has worked flawlessly. It is mounted under the solar panels open to the air. It appears no worse for the wear.Update: It's been through another brutal Winter outside and is still working!Update: 3 years and counting, still works like a charmThis isn't the cheapest controller out there. It's not even the first one I bought. However, it's the one that I wish I bought first.Morningstar's website doesn't just have user manuals. The publish entire circuit diagrams and diagnostic manuals for their devices. If you read through some of these you will see some of the features that other devices don't have that this does which aren't advertised. Some examples-Operates at up to 60 C (that's 140F, which the inside of a badly ventilated shed like ours needs!)-Reverse polarity protection along with a host of other self checks that prevent you from frying the device (unlike cheaper products).-What specifically it does when you change the jumpers from flooded battery type to AGM type-How to troubleshoot problems beyond the token errors that anyone can figure out themselves (i.e. requires a multi meter--this is a good thing)-Various other protections for the solar cell, the load device, and the ability of the device to separate these things from each other (specifically)The one downside is I wish it came with the 2 prong plugs like many other devices do. Fortunately my cheaper, dead controller had them-- I just cut them off and stripped the wires and the installed into the SunSaver no problem.This controller works well. As I type this in the morning, I'm getting 13.53 volts on the "SOLAR" terminals and 13.40 volts on the "BATTERY" terminals. That's a hair under 1% voltage drop in the controller--not bad. I have never found it to get hot to the touch--but I put a metal heat shield between it and the wall, just in case.The indicator lights are annoying at night. I made a cover for it which works well (just a piece of cardboard wrapped in black Gorilla tape, and a couple of holes poked in it to go on the controller's mounting screws) but it would be nice if there were a switch to turn off the lights.I find the battery state-of-charge indicator to be just a rough guess. It's based on battery voltage, and it can be easily fooled by putting a fairly heavy load on the battery for a short time. It would be best to install a separate amp-hour meter.Works wellExcellent product. Hooked up correctly