We frequently get requests from customers asking for dual inverters to handle their 50A split phase systems. Here are our thoughts on the topic.
Shore Compatibility Issues - When connecting to any shore power source less than 50-amps, a dual inverter system won't be able to supply pass-through power through both inverters and some dual inverter systems won't allow power to pass-through on either inverter. Split phase inverters are very finicky about AC input and typically reject most AC input that is not from a 50-amp shore power connection. In some dual inverter setups (Like Victron's Multiplus and Quattro), you have the option of passing through single-phase power on one inverter while the other inverter on Line 2 is only capable of inverting. This presents some issues if you want to run any loads on Line 2 because Line 2 will be limited by the inverter’s inverting capacity (rather than the pass-through limit) and it will draw down the batteries. If the Line 1 inverter isn't able to keep up with the demand via its internal charger, then you will deplete your connected battery bank while on shore power.
Energy consumption – Because of an inverter’s no-load current draw, dual inverter systems draw more power to operate. This is most noticeable when leaving the inverter on idle and running no loads or small loads. At a low 20W per inverter (sometimes twice that), split phase output can be 960Wh per day or the equivalent of what 320W of solar panels would produce.
Generator Compatibility Issues - Almost all generators have limited functionality with a split phase inverter system. All single-phase generators have the same dual inverter system compatibility issue listed above with shore power connection less than 50-amps. Additionally, most dual-phase generators used in RVs don't have the very clean AC output and are rejected by the dual inverter system. This causes the same effect as the single-phase generator or shore power, leaving you with very limited functionality on Line 2 loads and less power distribution.
Cost and Space - Installing two inverters takes twice the amount of time and almost twice the materials as a single phase inverter. This can increase the price of your project dramatically, especially if you are paying someone else to do the installation. In addition to the cost increase, the amount of space needed to install two inverters, and double the wire runs, takes away from battery or other storage space. Most RVs don't offer enough space to install two inverters while keeping them close to the batteries.
The solution - AM Solar has designed the Smart Phase Selector (Patent Pending) which optimizes the way the inverter supplies power to the coach allowing a single inverter to supply both legs whenever needed. The total power supply available would, of course, be limited by the rating of the solar inverter, and if an output voltage of more than 3000VA is needed, we recommend a 24V battery voltage system with a 5000VA inverter. Additionally, the Victron Multiplus II 3000VA inverter has this feature built-in.
For use with 50A coaches, the MultiPlus-II is a powerful true sine wave inverter, a sophisticated battery charger that features adaptive charge technology, and a high-speed AC transfer switch in a single compact enclosure. Rated at 3000VA.
Note: Some Keurig coffee makers are known to be incompatible with inverters. In some cases, this will just result in a loud buzzing noise while operating, and in other cases, it will result in inverter overload and failure to operate. This doesn't mean your inverter will be damaged or that trying to use your coffee maker is dangerous; however, AM Solar cannot support compatibility issues resulting from a Keurig coffee maker. We recommend doing some research and purchasing a different coffee maker if you find yours to be incompatible with your inverter system.
Steady State: 2400W
Surge: 6000W
Voltage Output: 120V AC
Voltage Input: 9.5-17V
No Load Draw: 8-20W
Waveform: Pure Sine
Frequency: 60hz
Charger: 120A
Passthrough: 2x50A
Efficiency: 93%
Dimensions: H 22.7" x W 10.8" x D 5.4" (48lbs)
Extra: PowerAssist
Similar to the MultiPlus, the Quattro is also a combined inverter and charger. Additionally, it can accept two AC inputs and automatically connect to the active source. Its many features include a true sine wave inverter, adaptive charging, hybrid PowerAssist technology plus multiple system integration features such as three or split phase operation and parallel operation. Rated at 5000VA.
Please note there is currently a nation-wide shortage of Duplex AC breakers (primarily 15/20). Our kits are designed to include these, but we may need to make substitutions due to stock level. Please email info@amsolar.com if you have any questions about this.
Steady State: 4000W
Surge: 10000W
Voltage Output: 120V AC
Voltage Input: 19V-33V
No Load Draw: 10-30W
Waveform: Pure Sine
Frequency: 60hz
Charger: 120A
Passthrough: 2x 100A
Efficiency: 94%
Dimensions: (24V) H 17.5" x W 13.0" x D 9.6"
Extra: PowerAssist