10 Things to Consider When Buying Off-grid inverter

Looking for recommendations for off-grid inverters for a system with these characteristics:

• 48V
• un-inspected: off-grid, no building or electrical inspections required
• ~6 KW solar panels expanding to 12-18 KW over time
• PV array would probably settle in at around 400 V, 19 A initially, expanding to multiple arrays
• battery storage (looking at the EG4 batteries at the moment)
• ft elevation
• many days below freezing, with many also below zero
• ~5-6 KW of inverter capacity initially, expanding if required
• 240 V required
• The cabin will be uninhabited 3-5 days/week
• generator backup, and I have a Honda EU700is generator, currently without autostart

If you have an inverter brand/model recommendation based on your experience, please indicate why you recommend, and pros/cons. I've seen a lot of discussion of issues with certain brands on this forum, but not anything collecting it into one place for my scenario.

Research so far:

• Sol-Ark 12K: Perhaps not the best for off-grid use. Seems to include features that benefit grid-tie systems that I would not want to pay for. Seems touchy, as a lot of folks have struggled with it shutting down with slight imbalances on the AC legs. Needs an additional autotransformer to overcome this. Pricey.
• Victron Quattro KVA: Seems straightforward. You buy two to get 240 V. Not UL listed, which does not matter for me. Less pricey than Sol-Ark for two. Reputable brand.
• Growatt W 48V: Price seems too good to be true. Needs an autotransformer to produce 240 V. Relatively high idle watt usage. Reputation of the brand? Reliability? Longevitiy?

Would appreciate any advice you guys can provide as I embark on my design.

Research so far:

• Sol-Ark 12K: Perhaps not the best for off-grid use. Seems to include features that benefit grid-tie systems that I would not want to pay for. Seems touchy, as a lot of folks have struggled with it shutting down with slight imbalances on the AC legs. Needs an additional autotransformer to overcome this. Pricey.

Your research is probably based on listening to David Poz who knows nothing about electronics and very little about Solar equipment.
Sol-Ark 12K or the Sol-Ark 15K makes for a great off grid Inverter and so long as you update the firmware (which POZ did not do) and you balance your loads properly (which all installer do) you will be fine.

• Victron Quattro KVA: Seems straightforward. You buy two to get 240 V. Not UL listed, which does not matter for me. Less pricey than Sol-Ark for two. Reputable brand.
• Growatt W 48V: Price seems too good to be true. Needs an autotransformer to produce 240 V. Relatively high idle watt usage. Reputation of the brand? Reliability? Longevitiy?

Would appreciate any advice you guys can provide as I embark on my design

If price is your driving factor then I assume Sol-Ark is out of the mix. Other brands like Outback and Schneider are not going to be any cost savings over Sol-Ark, so your really limited to Growatt with all of it's issues going Split phase or you could try the MPP LVX. Price is not my primary concern. Actually the primary concern is reliable power without the inverter tripping for when we are away from the cabin. I can certainly balance the loads, but I would rather have an inverter that can compensate for reasonable imbalances. I do not want to be trying to instruct the family where they are allowed to plug in a heater or a blow dryer, so at least a W permitted imbalance between 120 V legs would be appreciated. For while we are away, I can pretty precisely control the minimal loads to be in balance (refrigerator, freezer, some minimal resistance heating).

I had not seen the MPP one, and on initial review it looks interesting. Is there much experience out there with the Victron Quattro? I have installed several Victron MPPT charge controllers and battery monitors on RVs, but never used an inverter of theirs. I am impressed with the quality in the products I've used.

Back to price: If I can get reliable power for $2k or $4K rather than spend the $7k for the Sol-Ark, I would need to be sold on the advantages to spend the extra money - and I am willing to be sold if the case is made.

One thing I forgot to mention in my parameters: remote monitoring over the internet is a BIG plus, and it looks like the MPP at least advertises that. Going off grid, the biggest let down to me was the idle power on different brands. Victron and Giandel have the best performance. My Victron Phoenix 375VA uses 13 watts idle. In contrast, the Growatt (forgot model) measured 70 watts! MPP LV , a split phase 240, measured 60 watts. There's one growatt, I forget which model, that uses 130 watts idle! That's 130 watts * 24 = or 3 KW wasted of battery, solar panels, connectors, etc for absolutely NOTHING of value. Once you go off grid and realize how much of a waste that is... it is very upsetting. With my Phoenix 375VA, having 13 watts idle is only wasting 312 watts per day. And I plan on putting a bus bar in and hooking up my MPP LV for w loads. On Victron, I can use my 's bluetooth to turn it on and off in bed, saving 8 hours of usage.

I am not sure about Outback, Schneider, Sol-Ark idle power consumption.

If you are an off grid inverter company the idle power consumption should be the #1 advertised feature, put up at the top, or in the model number itself.

The Victron Quattro KVA is suppose to have low watt usage. I seem to remember it is the same as the Phoenix 375VA but I'd look it up.
I would go for that if you already picked it out. Look for a thread for idle power consumption usage here and see if somebody reported it.

Going off grid, the biggest let down to me was the idle power on different brands. Victron and Giandel have the best performance. My Victron Phoenix 375VA uses 13 watts idle. In contrast, the Growatt (forgot model) measured 70 watts! MPP LV , a split phase 240, measured 60 watts. There's one growatt, I forget which model, that uses 130 watts idle! That's 130 watts * 24 = or 3 KW wasted of battery, solar panels, connectors, etc for absolutely NOTHING of value. Once you go off grid and realize how much of a waste that is... it is very upsetting.

Any low frequency inverter will draw around that, doesn't matter which manufacturer. If someone is buying a low frequency inverter, they are purchasing it for a reason, high amperage starting loads.

You're comparing apples to oranges. If you want to post statements like that, you should differentiate what type of inverter instead of posting what you have.

Price is not my primary concern. Actually the primary concern is reliable power without the inverter tripping for when we are away from the cabin.

One thing I forgot to mention in my parameters: remote monitoring over the internet is a BIG plus, and it looks like the MPP at least advertises that.

SMA will even monitor it for you and send a message if something goes wrong. Put Schneider XW Pro with MPPT 100a 600v SCC, and an insight gateway on your shopping list.

That will get you started and I think it meets your design requirements. It's expandable to more Solar by adding additional MPPT controller or if watts continuous output with surges up to isn't enough power, you can add another inverter. Completely Scalable.
It is customizable as far as charge and battery parameters and I run my with the EG4's now.
It has a "search mode" for off grid no low power savings. This maybe useful in your setup, if you have periods of no load.
It's massive LF design that weights 140lbs and built to last and handle large motor loads, etc. No autotransformer needed with this inverter!
If you have Internet access, you will have complete monitoring and control of your system remotely thru insight cloud.

Cost wise, it's middle of the road, more than the cheap Chinese import inverters, but less than a Solar-Ark. I think they are a good value for the quality of the equipment.

You mention freezing temps. Those EG4's should NOT get below freezing. You ned to keep them above freezing or they will not be happy.

The Sunny Island's are the best, by far, not even a close second place. Remote monitoring is not available however.

I think it is, by several generations of datacom equipment.

I presently have Sunny Web Box connected, which can see and adjust both Sunny Island and Sunny Boy.
Not advisable for internet connection because they gave it a hardwired admin password.
I also have the earlier Sunny Data Control.

Other interfaces are currently marketed by SMA.

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Murph,
Don't the Sunny Islands require a separate PV controller ?
So couldn't he monitor it remotely with something like a Midnite Solar Classic ?

You can use DC coupled SCC, but better is AC coupled, e.g. Sunny Boy GT PV.

Murph,
Don't the Sunny Islands require a separate PV controller ?
So couldn't he monitor it remotely with something like a Midnite Solar Classic ?

Like Hedges said, you can DC Couple them like most other off grid inverter systems, but they are capable of AC coupling, which is a better way of going off grid in my opinion.. Not a lot better, but I think AC Coupling has advantages, especially if you're driving loads during the daytime hours.

The problem with the Sunny Islands is that they lack features.. They're designed to do a job and they do it exceptionally well, but they lack all the bells and whistles if you're into that.

Its a $ inverter and they equipped it with a 2 line dot matrix display that's 2.5 inches wide and 5/8 inch tall.. LOL

Current plan for battery location is in a sub-basement or root cellar that will keep the batteries above freezing. The BMS on the EG4s also will shut down charging < 32 F. Is there more I should be considering?

Charge rate allowed is something like 0.5C at temperature of 25 degrees C, taper down to maybe 0.1C at 10 degrees C, taper further to freezing.
My suggestion is determinate max charge rate available and set temperature of charge disconnect in BMS accordingly, something higher than freezing.

A heater may help. I could imagine a root cellar having warm dirt but cold air. Insulation may help, or further earth sheltering.

Some systems (All-in-ones, Victron, AC coupled systems) should be able to regulate max battery charge current while allowing higher wattage from PV if there are loads consuming it. (Only beneficial for some systems with large PV, small battery.)

Put Schneider XW Pro with MPPT 100a 600v SCC, and an insight gateway on your shopping list.

Looking at the specs for the Schneider/Conext XW Pro , surge capacity is 2X capacity for 60 seconds, which is a lot. Also, the weight of the inverter is 122 lb. (comparatively more than other similar capacity inverters). I've understood that both of these are indicators that the inverter is low frequency. Can someone confirm? Also, it outputs 120/240 VAC without an external autotransformer. At ~$, it seems like a pretty good deal for a LF inverter with good specifications and features. One thing that is not clear in the literature for this inverter is what kind of charge controller is included, if any. It is called an inverter/charger, but looks like it may only come with a PFC charge controller, which is not great.

What's the experience of the group with this inverter? Inverter/charger meaning battery DC to AC, and AC charges battery.
Usually that means grid or generator input charges battery.
This one mentions DC or AC coupling, which should mean grid tied PV inverters can be connected, and this unit will draw power from them to charge battery. Probably uses frequency shift to regulate them, so if GT PV inverters have frequency-watts it can play nice.

You might buy your favorite MPPT SCC to go with it. If same brand they could communicate.

Schneider Electric XW Pro Inverter/Chargers

Schneider Electric XW Pro Inverter/Chargers can be used for off grid or grid tied applications. Now with higher power ratings and improved battery management.

What is an off-grid inverter?

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An off-grid inverter, also known as a standalone inverter or independent inverter, is a type of power conversion device used in off-grid or standalone electrical systems that are not connected to the main electrical grid. The primary function of an off-grid inverter is to convert the DC (direct current) electricity generated from renewable energy sources, such as solar panels, wind turbines, or batteries, into AC (alternating current) electricity suitable for powering household appliances, machinery, and other electrical loads in locations where grid power is unavailable or unreliable.

Off-grid inverters are commonly used in various applications, including off-grid cabins, remote homes, RVs (recreational vehicles), boats, and in regions with unreliable grid power. They are a crucial component in off-grid renewable energy systems, providing a means to convert and manage renewable energy into usable electricity for daily needs.

How to choosing the Right Off-Grid Inverter?

Choosing the right off-grid inverter is a critical decision when setting up an off-grid power system. Here are the steps and considerations to help you make an informed choice:

1. Determine Your Power Requirements:

   - Start by calculating your power consumption needs. List all the electrical appliances and devices you plan to run, along with their power ratings (in watts or kilowatts) and estimated daily usage.

2. Select Inverter Type:

   - Decide whether you need a pure sine wave inverter or a modified sine wave inverter. Pure sine wave inverters are more suitable for sensitive electronics and appliances, while modified sine wave inverters are more affordable but may not be compatible with all devices.

3. Inverter Capacity (Wattage):

   - Choose an inverter with a capacity that can comfortably handle your peak power demands. Ensure it has enough wattage to start high-power devices (like refrigerators or power tools).

4. Input Voltage and Voltage Range:

   - Determine the DC input voltage of your renewable energy source (e.g., solar panels or wind turbines). Ensure that the inverter's input voltage range matches the voltage your system generates.

5. Battery Voltage Compatibility:

   - Match the inverter's DC input voltage to your battery bank's voltage. Common battery voltages for off-grid systems are 12V, 24V, or 48V.

6. Efficiency and Standby Power Consumption:

   - Check the inverter's efficiency rating. Higher efficiency means less energy loss during the conversion process. Also, consider the inverter's standby power consumption, as this can affect long-term battery life.

7. Surge Capacity:

   - Look for an inverter with a surge capacity that can handle the momentary high-power demands when starting certain appliances (e.g., refrigerators, well pumps). Surge capacity is typically higher than the continuous power rating.

8. Battery Charger and AC Pass-Through:

   - If you plan to charge your battery bank with a generator or grid power, consider an inverter with a built-in battery charger. Some inverters also offer AC pass-through, allowing you to switch between inverter power and grid power seamlessly.

9. Monitoring and Communication Features:

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   - Consider inverters with monitoring capabilities that provide real-time data on system performance. Some inverters offer communication options like Wi-Fi or Ethernet for remote monitoring and control.

10. Warranty and Reliability:

    - Research the manufacturer's reputation and warranty terms. A reliable inverter with a good warranty can provide peace of mind and long-term support.

11. Budget Constraints:

    - Set a budget for your inverter, but keep in mind that it's a critical component of your off-grid system. Quality and reliability should be prioritized over cost savings.

12. Consult a Professional:

    - If you're unsure about any aspect of selecting an off-grid inverter, consider consulting with a renewable energy system professional or an electrician with experience in off-grid installations. They can provide personalized recommendations based on your specific needs.

By carefully considering these factors and doing thorough research, you can choose the right off-grid inverter that will effectively meet your power requirements and ensure the reliability of your off-grid power system.

Can off-grid inverter work without battery?

Most off-grid inverters are designed to work in conjunction with a battery bank as a crucial component of the off-grid power system. However, it is possible to operate some off-grid inverters without a battery, but their functionality may be limited, and there are important considerations to keep in mind:

1. Limited Output: Without a battery bank to store excess energy, the inverter can only produce power when the renewable energy source (e.g., solar panels or wind turbines) is actively generating electricity. When the renewable energy source is not producing power (e.g., during the night for solar panels), the inverter cannot provide power to your loads.

2. Instantaneous Demand: Off-grid inverters without batteries may be able to handle the instantaneous power demands of your electrical loads while the renewable source is generating power. However, they cannot provide sustained power during periods when the renewable source is not active.

3. No Energy Storage: Without a battery, any excess electricity generated by the renewable source that is not immediately consumed by your loads will be wasted. This can be inefficient and result in an inconsistent power supply.

4. Grid Tie Not Possible: Off-grid inverters are typically designed to work independently of the grid, and they may not have the capability to synchronize with the grid or export excess power to it. This can limit your options for selling excess power or utilizing grid backup.

5. Load Considerations: The types of loads you can power without a battery will depend on the inverter's capacity and the power demands of your appliances. High-power loads or loads with starting surges may not be supported without a battery.

In summary, while it is possible to operate some off-grid inverters without a battery, it is not the most practical or efficient way to use them. Off-grid inverters are generally designed to work in combination with energy storage (batteries) to ensure a consistent power supply in off-grid applications, providing power when the renewable energy source is not actively generating electricity. If you don't plan to use batteries, you may want to consider alternative solutions, such as grid-tied inverters for net metering or hybrid inverters that can operate in grid-tied and off-grid modes.

SRNE ASF Series Off-Gird Inverter comes with a multitude of powerful features, making it an outstanding energy management solution. To start with, it supports both lead-acid and lithium-ion battery connections, offering you greater flexibility and choice. What's more, it boasts a unique dual activation function that can trigger the lithium-ion battery into action either through the main power supply or photovoltaic source when it's in standby mode. This feature ensures that your power source remains reliable and efficient.

Our product also supports split-phase and single-phase pure sine wave output, accommodating various voltage requirements, including 200\208\220\230\240Vac per phase. Additionally, it supports two solar inputs and simultaneous tracking of two solar maximum power charging/carrying capacity functions, with an impressive 99.9% efficiency and a maximum 22A current in a single circuit, perfectly suited for high-power modules.

You have a variety of charging modes to choose from, including solar-only, mains priority, solar priority, and mixed mains/PV charging. Furthermore, the product offers a time-slot charging and discharging setting function, allowing you to set the time periods for switching between mains charging and battery discharging, as well as mains bypass power supply mode.

To reduce no-load energy losses, we've included an energy-saving mode. The product offers two output modes, utility bypass, and inverter output, with uninterrupted power supply functionality.

With its LCD large screen featuring a dynamic flow diagram design, you can easily understand the system data and operational status. Moreover, we provide comprehensive 360° protection, encompassing complete short circuit protection, overcurrent protection, undervoltage protection, overload protection, backfill protection, and more.