ECO-WORTHY 4 String PV Combiner Box with Lightning Arreste, 12A Rated Current Fuse and Circuit Breakers for On/Off Grid Solar Panel System

I really love these little boxes. I've got three of them now. They make messing around and reconfiguring panels incredibly easy and safe. And if the topology isn't quite what is needed, everything is on a DIN rail making it easy to adjust the bits and pieces.Please note that the PUFA 2-pole breaker in the box is polarized. It appears to be wired correctly for the current direction but generally speaking polarized breakers are a bad idea in solar systems. So just be aware of this.My only critique is that the four little metal mounting tabs rust. Not enough to remove a star, though. 5 stars.In terms of using them, you need to know the basics about putting panels in series and putting strings in parallel. The combiner box combines series strings by paralleling them. Putting solar panels in series adds voltage but leaves the current the same. Putting solar panels in parallel adds current and forces the voltage to be the same.* With a combiner box, you do not parallel your panels or strings prior to going into the box. You parallel them through the box. That is what the box does, it allows you to safely parallel panels or strings. So the 10A current limit per input is not usually a problem. The fuse is there to protect the panels from shorts. If a string shorts out, all the other parallel strings will feed their current into it and that MUST blow the fuse. So you must size the fuse properly. Typically 12A, 15A, or 20A is the proper size for this function.* IT IS VERY IMPORTANT TO SIZE THE FUSES PROPERLY SO THEY BLOW IF TWO OTHER STRINGS FEED CURRENT INTO A SHORTED STRING. It is good that the unit comes with 12A fuses, that is almost always the correct size. If you screw this up you risk catching your wiring or panels on fire if a short develops. Panels have a "maximum series fuse" specification. Make sure the fuse is around that value.* The maximum current is a specification on the solar panel. Nearly all solar panels are either 5A or 10A and they can achieve this current regardless of the latitude. Assuming your strings are in series and that is what is fed into the box, then you want the current specifications for all the panels in series to match because if it doesn't one panel will restrict the current of the others and you will not get full production.* You want the voltages of all the strings you are combining through the combiner box to be roughly similar. The currents coming from each string into the combiner box can be different.* Remember, you have to add voltages for the panels making up each string and the string is then fed into one input of the combiner box, which adds currents. The rule of thumb here is that you want the operating voltages of each string to be similar and you also want the operating voltage for each string to be LESS THAN the open-circuit voltage for any of the strings. You don't want an operating voltage that is higher than the open-circuit voltage of any of your strings due to mismatching the strings, that can cause severe problems down the road. Solar panels are not designed to take indefinite reverse voltage (which is why larger combiner boxes have blocking diodes as well. Smaller combiner boxes typically do not have blocking diodes).* Severely mismatched strings will not give you optimal generation, but if you don't have a choice then its better than nothing. That said, you have to make absolutely sure that the operating voltage for any string does not exceed the open-circuit voltage for any other string (when the strings are mismatched), as per the label on the solar panels. I'm saying this a second time because it is important.--* The BACKHAUL wiring is the wire that goes out of the combiner box through the large breaker and goes into your charge controller or hybrid solar inverter or whatever. You have to make sure that the backhaul wiring can handle the total combined worst-case current from the combiner. Typically this is going to be in the 15-25A range. Using 10 AWG wire for your backhaul is always a good idea because you will reduce losses through the cable. High quality solar cabling is typically 6mm^2 which is actually a bit better than 10 AWG (it's more like 9 AWG).* Make sure the MC4 connectors are rated for the current being carried. This is typically not an issue for each individual string (because the current is only 5A or 10A), but it can be an issue if you are using MC4 connectors on the backhaul cabling where the total current can be far more. Once the array is operating, on a good sunny day hand-feel the MC4 connectors on the backhaul (if any) to make sure they aren't hot.* Generally more voltage and less current is better, you get far lower losses that way, but you have to make sure that the open-circuit voltage of the strings does not exceed the specifications for the charger controller that you are backhauling into.--* Now for voltage, that is mostly a function of the charge controllers your are feeding into. Make sure that voltages, particularly the open-circuit voltage of the strings, is compatible with your charge controller.* Charge controllers are not usually limited by the input current from the combiner box because most people use panel geometries that add voltage before combining the strings in parallel. Instead, most charge controllers are limited by their output current, which is generally a function of the battery voltage they are feeding into.* I strongly recommend using Victron charge controllers, which are 97% efficient, whenever possible. Victron has two reasonably-priced charge controllers, the MPPT 75-15 (max 75V in, roughly 10-30V out) and the MPPT 100-20 (max 100V in, roughly 10-60V out). 15A or 20A output current, max. These charge controllers need BATVOLTAGE + 5V coming into it from the combiner box in order to start. This is not usually a problem since you will be putting panels in series to create higher voltage strings anyway if you are smart.* Have fun! I am! I have three of these babies.

Got this to go with the ecoworthy black friday deal from last year. I've seen a few rough stories in the reviews but so far I've been one of the lucky ones. Everything I've purchased from Eco-Worthy has been well made, well packaged, and just great construction. I only tinker with solar and dont really know much about it. But I do know what a well built item looks like, and this is it. Very happy, but if things go sideways I'll update my review.

Good deal, works very well, and very easy to install. Glad I bought this combiner box especially for the price.

Not sure where negative reviews are coming from. Some as moronic as saying terminal caps aren’t tight. We’ll get some Channel Locks genius. This thing is well made and works great with my 1Kw 6 panel 24V system. Tidied up the wiring and very simple to install if your IQ is above 100. 4 stars because: (a) there are no instructions except online and they have inconsistent, conflicting pics and wording (e.g. pics showing which leads are + and - are backwards); and (b) Customer service gives super fast responses but English is clearly not their native language. Will buy a larger one for my next project which is a 5Kw system.

Nice unit

I've installed several of these combiner boxes and they always perform well. Happy Customer. I like being able to find the same brand available repeatedly so I have a hope of consistent quality so I am pleased to find these available and that I find them to be reliable.

So far, so good. Bought this to replace my midnite combiner because the bus bar and breaker design was frankly horrible. There was zero waterproofing whatsoever and I simply didnt like the rickety design. This ecoworthy box is much better. The breaker and bus bar setup is pretty robust, the case is watertight, and the connections are solid. I had to torque a few of the screws for the connections, but that was it.

Reading the Owner's manual upon arrival, it (logically) says to buy extra replacement fuses for this product.Lots of luck finding them!I searched both the Ecoworthy website and Alibaba for the 12A, 1000W DC fuse, form factor 10mmx38mm for solar PV applications. You have to buy a minimum 100 quantity (around 65c each) from the Chinese fuse manufacturers. So these things are VERY cheap in bulk.So Ecoworthy, where can I buy ten of these for $6.50 plus shipping for 10 VERY small items???I'm not even gonna install this product into my off-grid solar system until I have spare fuses.I advise you NOT to buy this product until Ecoworthy fixes what should not be an issue AT ALL.