I bought this so I could expand my two panel system up to four panels. It appears to be working fine. The instructions were lacking but the diagrams on the unit give all the info needed. This unit does not have the auto on and timed shut off the 10 Amp units appear to.
This 20 amp controller is exactly what I needed for my Solar electric trike.
I previously purchased an MPPT 15 amp controller that would trip out daily during my ride to and from work (about 1.5 miles one way) That was my poor shotgun guessing skills. When I did the math and found I was drawing 18 amps I saw my problem.
So far the unit has tripped once due to an undervoltage, this was after putting about 10 miles on the bike and then climbing a hill.
I've had this controller for about 3 weeks and have had no other issues.
Buy HQRP 20A Solar Panel Battery Charge Controller / Regulator 12V / 24V 20 Amp 300W with PWM Type of Ch Now
First, let me say that I am not an electrician of PV professional. I do not claim any expertise, but I do claim to have done and continue to do research. I know nothing about this subject 1 year ago.
Now, let's consider the intended use of this unit. It is NOT a high end solar/wind charge controller and it does not pretend to be so my rating is not comparing it to a MidNite Solar MPPT 250VDC 61A unit costing $700+. This is an inexpensive piece of Chinese electronics made for 4-stage battery changing in tiny-to-small PV systems. Based on everyone else's comments, it works fine when used within it's rated capacity and does not work when used outside of its rated capacity. Go figure. If like some comments indicate you have no idea what wire gauge to use given your voltage and resistance due to temperature and conduit run length, if you don't know to look at the NEC sections 310.15 310.17 to determine appropriate conductor ampacities, well... you may need to either do a little more studying (Photovoltaic Design & Installation for Dummies by Ryan Mayfield is a most excellent resource if read diligently and not a dust collector on a shelf), or pay someone who knows what they are doing to set up your PV system, or simply return your unit and cease talking about things you don't know about. DIY projects should only be undertaken by DIYers willing to perform due diligence research instead of purchasing mismatched components. If you smoke your inverter it is 95% probably because you screwed up, not because the inverter was mis-wired internally. Even diligent research may not be enough, but it is better than ordering things randomly and rating it a 1 without even knowing what wire gauge to wire it up with.
As for the product review: The controller is housed in a respectably thick plastic box with a metal backplate. As someone complained, yes it rattles when it is shaken. This is due to two things: the On/Off button (far right) rattles on the housing, and the wire connection panel (center bottom) which is attached to the circuit board rattles when no wires are secured. Neither of these are defects, it's just that this is made using inexpensive design (a spring would have stopped the On/Off button rattle) and the rattles of an out of the box unit are a by-product of that. When screwed into a plywood mounting board, nothing will be rattling. There are no loose parts in the unit.
This unit is made by an unknown manufacturer. HQRP purchases the units from the manufacturer, slaps an HQRP sticker on the unit face, and ships it. The packaging box does not even show HQRP anywhere. The take away from this is that this is a commodity item, purchased by many companies such as HQRP who put their own peel-off sticker on the housing. The brand is not really HQRP, the brand is China.
I certainly do not expect this unit to last long a few years at best. It has two 35A (or was it 30A?) auto-style fuses soldered directly onto the circuit board. If your unit ever quits working, remove the 4 back plate screws, then remove the 4 circuit board screws, and pull the board and check the fuses. It that's the problem, just use a soldering iron ($8 on Amazon) with rosin-core solder to replace fuses if necessary. Make sure the finished solder got hot enough to solidify smooth and shiny and not gray and grainy looking.
I plan on putting 20A fuses (what it's rated at) in front of the unit to insure they burn out before the 35A fuses inside the unit, and I'll gang my 24V panels appropriately to keep peak amperage under 20A.
My plan is to build out my PV system over years as finances allow. As a starter controller, this is a good choice given my current panel/battery setup. Later as I upgrade it can be re-purposed for my horse trailer or shared with my daughter for a science project or reboxed and shelved in a Faraday cage as a backup.
Compared to a "real" PV system component such as from MidNite Solar or Outback Power, this unit rates a 2. But that's comparing an apple to an orange tree. For it's niche, this is a nice little controller with a lot of good features. It does exactly what it is intended to do to provide an inexpensive controller/regulator functionality for a small 12/24VDC PV system. In achieving that goal, it deserves a 5.
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At first I didn't know how this solar controller would work in an RV. After installing it I am pleased with the way it operates. One of the lessons learned was to hook up the wiring in the sequence noted in the installation instructions. Otherwise, it will not operate. The installation and operating instructions are vague and need a little more information.
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Used this Charger to charge 4 Golf Cart Batteries from my 10 amp solar array.
Worked very well for about 3 months. I burned it up trying to hook up an amp meter (through a shunt) even then it took two days to smoke a transistor.
Replaced it with a 30 amp MPPT charger for $99.
