Previously, Enphase only allowed their battery systems to be operated in a grid-interactive manner, meaning that you had to have a grid connection to commission and use their battery systems. The intent was strictly to have batteries for occasional backup purposes or to take advantage of time-of-use or zero-export needs where available or necessary.
Effective July 2024, Enphase now allows completely off-grid use of their Enphase Battery 5P with additional required components when certain criteria are met and the installer is trained and certified on off-grid system design and installation.
I have received the required training and we are ready to start offering Enphase systems for small to mid-size off-grid systems. More on the sizing limitations later…
Running Enphase Batteries Completely Off-Grid
To operate an Enphase battery system in off-grid only mode, there are several requirements, and also some limitations.
Requirements for Enphase Off-Grid Systems
The most significant requirements are:
- An approved generator model of proper size must be installed with the system.
- Only works with IQ8 series rooftop microinverters and Enphase 5P batteries.
- Must use the Enphase System Controller 3G, which includes generator support.
- The largest single backed up load must not exceed the continuos output of the battery
- Broadband internet service must be available (if off-grid, you are likely to not have wire broadband, so satellite Internet like Starlink would be required).
- Your installer must have completed the Enphase University training for this specific application.
Limitations of Enphase Off-Grid Systems
While the Enphase system is incredibly consumer friendly and well designed, there are some limitations that will restrict the people who this product will appeal to. Most importantly, these limitations are:
- Maximum of 40kWh of storage capacity. Because all of the batteries must go through the single input on the System Controller, this is a hard limit. The generator support function limits the System Controller 3G to eight batteries, or 40kWh, while the non-generator System Controller 3 allows up to 16 batteries. Since the 3G version is required, this is a significant limiting factor for off-grid systems.
- Following along with the above limitation, even though eight batteries have a continuous power output rating of 30.72kW, or 128 amps, the single input on the System Controller 3G is limited to 64A. While you will have the full energy storage capacity of the eight batteries, you will only have the power output of four batteries when no other sources are available (solar panels or generator). While this is probably larger than the biggest power single appliance in your home, it could cause system shutdowns if multiple appliances are running or start simultaneously.
- Limit of 64 amps of microinverter input, which is 15.36kW of AC power. Generally, this means you will be limited to DC solar panel system ratings of around 20kW using popular panels that are on the market today.
Practical Use In The Florida Market
Most of the off-grid home requirements in Southwest Florida, and throughout most of the state, require a significant amount of energy storage. The 40kWh limit is less than most off-grid homes need to run air conditioning effectively, particularly without significant generator run time in the summer months. Therefore, these Enphase systems will be relegated to smaller homes, non-home use for dedicated equipment, and other scenarios where the energy storage needs are modest.
That’s not to say that 40kWh is a small amount of energy storage. The battery in an off-grid solar energy system serves as a buffer, storing energy for nighttime use and when demand outstrips supply (i.e. cloudy weather). When there is not enough solar energy to recharge batteries and the batteries are depleted, the generator will come on and supply power to loads and recharge batteries simultaneously.
However, this could result in significant generator run time for many full-time off-grid homes. When we design systems, we have to consider the worst case scenario. For off-grid homes, that is usually August and September when we have lots of cloudy weather and extreme heat and humidity.
It is a very challenging scenario for producing and storing enough energy for air conditioning when there is no grid present. Generator run time is inevitable in these scenarios unless the batteries and solar panels can be oversized. That is where we run into limitations with the Enphase system. It’s unfortunate that a full 80kW of battery capacity cannot be installed with an off-grid Enphase system, as you can do that for battery backup in a grid-tied system without a generator.
Missing Features
If you are looking for load control, DC coupling, interoperability with other equipment, or anything else outside of the Enphase ecosystem, you will want to look elsewhere. Enphase has simplified its offering, which has its advantages. They are not trying to be all things to all people.
Other hybrid inverter solutions allow both DC And AC coupling, robust load control, flexible (even portable) generator support, parallel stacking for very high output needs, and more. The Enphase system seeks to provide what most people want, while leaving out features that some contractors and system owners have come to expect.
Our Take On The Usefulness and Feasibility of Enphase Off-Grid
We love Enphase around here for many reasons. The remote monitoring and diagnostics are fantastic. And the systems just work. Because you have a single manufacturer of the microinverters, energy storage system, and microgrid interconnect device, everything just works seamlessly as it is designed to do. There are no interoperability issues, and a single manufacturer to call if help is needed (no finger pointing between manufacturers when system issues arise). And Enphase has best-in-class customer support. The warranty on the Enphase batteries and other components are also industry leading.
We absolutely intend to offer Enphase as the top choice for off-grid systems that meet certain criteria. For very small systems, the cost of the System Controller and an appropriately sized generator may be prohibitive. For larger systems, we start to run into the limitations mentioned above, which may take Enphase off the table. If there is existing off-grid equipment on site, integrating Enphase may not be a cost-effective solution, since we would be starting over. Retrofitting existing solar panels with Enphase microinverters is possible, but will only be recommended for very recently installed solar panels.
Enphase batteries are not perfectly suited to the Florida market for completely off-grid homes, but there are many applications where if can absolutely work, and work brilliantly.
Alternatives to Enphase for Off-Grid Solar Energy Systems
Since there are limitations to the sizing of Enphase systems for off-grid use, we continue to recommend Sol-Ark inverters with a number of battery options. The nice thing about Sol-Ark inverters is they are “battery agnostic,” and have many different operation modes. They can even start as an off-grid inverter and then switch over to a grid-interactive inverter (which could be useful in a new home build scenario).
The Sol-Ark inverters are known as “all-in-one” hybrid inverters that incorporate transfer switches and do all of the solar charge control, battery charging, and system control. They are becoming more and more popular.
Traditional hybrid inverters are still available. These incorporate transfer switches, but leave the solar charge control to external devices. These are tried and true, but recently we have seen once-popular manufacturers sell, consolidate, disappear, or otherwise become poor alternatives.
Final Thoughts on Enphase Off-Grid
The market is changing, and Enphase is really taking advantage of a giant hole we have in the off-grid space.
I am delighted to see that Enphase decided to allow their system to be used off-grid. Last year I asked them to make an exception when I was designing a system that would have been the perfect application for the Enphase batteries in a off-grid scenario. I was denied. It was such a perfect application that I briefly considered going against their guidance and tricking the system to work off-grid by connecting a generator temporarily to simulate the grid. In the end, I couldn’t take that risk.
It seems that Enphase listened and saw an opening in the off-grid market that they could fill. While it will not be flexible enough to meet the demands of all of our off-grid clients, some will really want to take a close look at what Enphase has to offer.
