After viewing my cabin solar system, a friend asked me to help him plan and install a similar system for his remote cabin. My system consists of 2,400 watts of solar panels, a Magnum MS4024PAE inverter/charger, a Midnite Classic, a 10,800-wh Trojan T-105 battery bank, and a 11-kw diesel generator. I use the generator for occasional heavy loads such as an air conditioner (3 or 4 times a year!) and a cloths dryer. This system has worked flawlessly for me over the last several years.
In consideration of his expected loads and budget, we decided that a 3 or 4-kw pure sine wave inverter would be sufficient. My friend’s system will not be required to operate heavy loads. His existing 3000-watt non-inverter gas generator was deemed adequate to charge the batteries and occasionally operate a 1500-watt water heater. We also planned to install 1800 watts of solar panels and a 10,800-wh flooded lead acid battery bank.
We originally intended to purchase a MS4024PAE and a Midnite Classic, however, at around $4000 (Canadian) it proved too much for his budget. In our search for an alternative, we found a Victron inverter that had excellent reviews, and a Midnite MN3024DIY hybrid inverter. According to the MN3024DIY spec sheet, this unit would provide the inverter, transfer switch, ac charger and an MPPT charger all in one unit. At approximately 1/2 half the cost of the Victron and a charger, and less then ¼ the cost of my Magnum and Classic, it was an attractive alternative. “Too good to be true”, we thought. But with the “Midnite” name stamped on it we were convinced to give it a try! If it didn’t work out for our purposes, we would go purchase the Victron equipment and resell the Midnite.
We purchased the MN3024DIY on eBay and a battery monitor from Amazon. The solar panels, batteries, and the associated hardware were readily available from local suppliers. Over a few days we were able to install the complete system and set up the inverter. When we powered the system, it worked exactly as expected. We tested the inverter with the usual household loads, being careful not to exceed the inverter’s rated total current rating, and it worked perfectly. When we started the generator, the transfer switch operated smoothly, and the charger kicked in and supplied current to the batteries (although not the full 40-amp charge, as the batteries had been fully charged before installation). Perfect system? Not quite!
My friend found a serious flaw in the system a couple of days after the installation. One morning he discovered his batteries were deeply discharged. The previous night he had turned the water heater on for 40 minutes. He assumed the heater was being powered by the generator. But this may not have been the case.
Apparently, when he turned on the water heater breaker at his distribution panel, the inverter Bypass had tripped and caused the heater to be supplied from the batteries rather than the generator. (I assume the inverter attempted to transfer repeatedly while the heater was on). Not good! Additionally, with the batteries now low, when he started the generator, he noticed the Bypass would trip as the ac charging current ramped up to its 40-amp setting.
Upon investigation we noticed the Bypass was tripping as the generator was responding to the increased load. According to the inverter display the input frequency was dropping 2 to 4 Hz., which was expected. The engine was not being overloaded and well within its output current rating. A second non-inverter generator gave us the same results. A quick reference to the Midnite Owner’s manual indicated the operating frequency range for the MN3024DIY to be 57-65 Hz.
Apparently, this inverter cannot be used with a non-inverter 3000-watt portable generator! We later confirmed this by borrowing a 2000-watt inverter generator from a neighbour. Even with the lower wattage rating the system worked perfectly within the limits of the generator current rating. A quick temporary fix was to reduce the charge current limit to 25 amps and to power the water heater and any other household load directly from the generator.
This issue was completely unexpected! My Magnum MS4024PAE has an operating frequency range of 50-70 Hz. And we assumed the Midnite would have a similar range.
If my friend’s generator had been an inverter type, we would not have found fault with the MN3024DIY. Installation and set up was straightforward and it worked exactly as we expected. In fact, the whole system operated nicely. Should it prove to be reliable and robust over the next few years I would recommend it as a good cost-effective alternative to LF units for similar installation requirements. Unfortunately, it seems that in this case any savings we made from selecting the MN3024DIY has been lost because my friend now needs to spend another $2000 on an inverter generator!
In consideration of his expected loads and budget, we decided that a 3 or 4-kw pure sine wave inverter would be sufficient. My friend’s system will not be required to operate heavy loads. His existing 3000-watt non-inverter gas generator was deemed adequate to charge the batteries and occasionally operate a 1500-watt water heater. We also planned to install 1800 watts of solar panels and a 10,800-wh flooded lead acid battery bank.
We originally intended to purchase a MS4024PAE and a Midnite Classic, however, at around $4000 (Canadian) it proved too much for his budget. In our search for an alternative, we found a Victron inverter that had excellent reviews, and a Midnite MN3024DIY hybrid inverter. According to the MN3024DIY spec sheet, this unit would provide the inverter, transfer switch, ac charger and an MPPT charger all in one unit. At approximately 1/2 half the cost of the Victron and a charger, and less then ¼ the cost of my Magnum and Classic, it was an attractive alternative. “Too good to be true”, we thought. But with the “Midnite” name stamped on it we were convinced to give it a try! If it didn’t work out for our purposes, we would go purchase the Victron equipment and resell the Midnite.
We purchased the MN3024DIY on eBay and a battery monitor from Amazon. The solar panels, batteries, and the associated hardware were readily available from local suppliers. Over a few days we were able to install the complete system and set up the inverter. When we powered the system, it worked exactly as expected. We tested the inverter with the usual household loads, being careful not to exceed the inverter’s rated total current rating, and it worked perfectly. When we started the generator, the transfer switch operated smoothly, and the charger kicked in and supplied current to the batteries (although not the full 40-amp charge, as the batteries had been fully charged before installation). Perfect system? Not quite!
My friend found a serious flaw in the system a couple of days after the installation. One morning he discovered his batteries were deeply discharged. The previous night he had turned the water heater on for 40 minutes. He assumed the heater was being powered by the generator. But this may not have been the case.
Apparently, when he turned on the water heater breaker at his distribution panel, the inverter Bypass had tripped and caused the heater to be supplied from the batteries rather than the generator. (I assume the inverter attempted to transfer repeatedly while the heater was on). Not good! Additionally, with the batteries now low, when he started the generator, he noticed the Bypass would trip as the ac charging current ramped up to its 40-amp setting.
Upon investigation we noticed the Bypass was tripping as the generator was responding to the increased load. According to the inverter display the input frequency was dropping 2 to 4 Hz., which was expected. The engine was not being overloaded and well within its output current rating. A second non-inverter generator gave us the same results. A quick reference to the Midnite Owner’s manual indicated the operating frequency range for the MN3024DIY to be 57-65 Hz.
Apparently, this inverter cannot be used with a non-inverter 3000-watt portable generator! We later confirmed this by borrowing a 2000-watt inverter generator from a neighbour. Even with the lower wattage rating the system worked perfectly within the limits of the generator current rating. A quick temporary fix was to reduce the charge current limit to 25 amps and to power the water heater and any other household load directly from the generator.
This issue was completely unexpected! My Magnum MS4024PAE has an operating frequency range of 50-70 Hz. And we assumed the Midnite would have a similar range.
If my friend’s generator had been an inverter type, we would not have found fault with the MN3024DIY. Installation and set up was straightforward and it worked exactly as we expected. In fact, the whole system operated nicely. Should it prove to be reliable and robust over the next few years I would recommend it as a good cost-effective alternative to LF units for similar installation requirements. Unfortunately, it seems that in this case any savings we made from selecting the MN3024DIY has been lost because my friend now needs to spend another $2000 on an inverter generator!
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