Spartan Power 50A 5500 Watt Automatic Transfer Switch Great for Solar & Wind Off Grid Systems

Original Review from 2020 - The unit arrived quickly, real quick! Pretty straightforward install. A small problem at first, but the customer service was good. However, I found the problem (some gunk got into the terminal block), fixed it quickly and the switch works perfectly! Updated Review from May 2024 - Well, it has now been a bit over 4 years and the unit still works great. I presently have a 2,700 watt solar array feeding into four, 24v battery banks that feed into a 24v, 2500 watt pure sine wave inverter. The transfer switch changes from solar to grid power depending on my battery conditions. It has worked flawlessly. I routinely run a 12k BTU minisplit heat pump, 800 watt HP graphic workstation, a pellet stove (backup) and my entire living room including 65" TV, lights, modems, etc. Batteries go low, it shifts quickly. Every now and then my big computer monitor (45") will turn off, but not the workstation and I just turn the monitor back on. Am not updating my solar system to 5,000 watts in the arrays and 12,000 watts of battery banks. Going to power up an additional minisplit heatpump. I'll update if any problems.

I used this switch to solve a problem I had. I first had put in four 100 watt solar panels with a 40 amp Renogy controlled. When I found that wasn't enough wattage to run my room air conditioner I installed four 320 watt panels with a 60 amp Renogy controller. My batteries were immediately being overcharged to 15.5 volts. Upon checking I found that the 40 watt Renogy controller is not designed to be ran in parallel. So I installed one of these switches to turn off the four 100 amp panels when the voltage reached 13.8 volts and back on when the voltage on the batteries reached 13.4 volts. I wired the four 100 amp panels to the left side of the switch which is what is normally the grid side. So far everything is working fine for now. In the future I'll probably replace the smaller controller with one that will run in parallel.

The product works as intended for the most part. Please make sure to dial in your voltage cutoffs or it will drain your battery to 0. Since the power to run the unit is connected directly to the battery system, it will continue to draw power even if the inverter shuts off. Additionally as many others have noted, there is an inaccurate voltage measurement that reads lower than the actual current voltage around 0.2 volts. This means that you have to put a bit of slop in your cutoffs, but that runs the risk of depleting your battery. I also wish there was a way to get ver ride the cutoffs if there was a power outage to keep vital systems online.

This product works as intended. However...... There is a design flaw in it. When this device is connected everything works fine. There is however no safety if the inverter fails. You will need to add a relay in the system so that is something happens to the inverter it will interrupt the 12v line and switch over to shore power. The system as designed - if the inverter fails the transfer switch is still connected to the battery and if the battery is still in the defined voltage the transfer switch will not switch over and will continue to supply no power to any device attached to it. Now with the relay in the system if something happens to the inverter the relay will cut off the 12 volt line which will make the transfer switch move to shore power. I hope this helps someone I will link the devices I used and attach pictures. https://www.amazon.com/MAGNECRAFT-725BXXSC3ML-120A-POWER-DPST-NO-120VAC/dp/B00DDEEZCE/ref=sr_1_1?dchild=1&keywords=725BXXSC3ML-120A&qid=1586289526&sr=8-1 although you can get them cheaper other places.

Just installed this and connected up to my little solar system a couple of days ago. I deliberately ran the air conditioner nonstop to test it, and it switched flawlessly when the battery dropped too low. No problems. I'm using it for a single 15-amp 110V circuit, so well below the rated power. Solar panels supply about a kW max, and I have six 12v deep-cycle marine batteries arranged as a 24v system. Air conditioner has a three-pronged plug, so I did have to set up a proper ground, which was not convenient with this switch. Would have been nice if you could just plug the switch into a 3-prong outlet to both ground its chassis and feed the ground through to an output 3-prong socket. Instead, I had to supply my own plug, sockets and ground.

My mistake......works just fine! Switch on top. I must have missed that sentence in the manual! Never powered up from the start. All proper protection in place. Nothing happened. Power at all three places but nothing shows on the display.

Garbage and not safe, tripped the GFCI on my inverter multiple times over the course of a couple weeks until it finally ruined my inverter. When it was working the transfer time was no where near as quick as they stated, noticeable delay when switching from Inverter to AC and vice versa. It’s a shame because I’ve been looking for something like this for awhile.

Easy to install, very fast transfer from one mode to another,my computer and monitor stay on.