Suggestions on choosing an inverter?

[rebelrider.mike]

Hey all.
I've been shopping around for inverters, and they've got me a bit confused. I'm totally new to the big ones, and I'll probably get some terminology wrong. I also don't really know where to look besides whatever randomly pops up in Google searches. But maybe you guys can help me figure this out.

I should probably let you know that I'm neither rich nor acrobatic. So this will all have to be done in stages while I recover financially from each one. And I'll have to hire out the solar panel installation. The primary goal is to have some power available to critical circuits during power outages. I figure 8 circuits based on how various things are split up in the main panel currently, and 6kW of power. I've actually counted up more like 4.5kW, but a buffer between typical and maximum would be nice.

Stage 1: Add a sub panel with the critical circuits. Fed by either the main panel (US grid) or by a 6kW generator. I'll also have a transfer switch so the grid and generator never get to "see" each other. This I could do pretty easily. The main panel is surface-mounted to a cinder block wall, and has room for more panels and boxes to be installed nearby. The wiring is also easily accessible.
Generator.png

Stage 2: Add the inverter and battery. Because my primary concern is having power during outages, the next step is adding a battery, rather than solar. And to use it I'll need an inverter. The idea is that for short outages, the battery can be used to power the sub panel until grid power is restored. For longer outages, the generator would still be used to run the sub panel when the battery is depleted, and can also recharge the battery. This may be less efficient, but it would allow the generator to not be run for several hours at a time. Depending on how conservative we are with our energy usage, and the size of the battery. At this stage, the inverter wouldn't need any particularly special features other than being able to deliver up to 6kW of power from the battery to the sub panel. An internal AC to DC battery charge controller would be nice, but an external one could also be used.
InverterBattery.png

Stage 3: Add solar panels. I determined a while ago that no amount of solar will power my whole house in the winter. I got 136 inches of rain last year, and my property isn't large. But what panels I can get would certainly be enough to make an impact on my electrical bill during nice weather. First priority for the inverter would still be to power the sub panel during outages. But now I'd need to either have a solar charge controller, or an inverter with one built in. I don't plan to produce enough power to back-feed to the grid for credit or whatever. But a smaller electrical bill in the summer would be nice to offset the large bills I'll get in the winter. Plus in a longer power outage, there might be some nice days where the solar could reduce my dependence on the generator.
Solar.png

So to sum up; here are some things I'm looking for in an inverter:

-Needs to provide up to 6kW of power.
-I think because of the amount of power, it will need to be 240V split phase. (The generator and sub panel will be split phase.)
-Would be nice to be compatible with the grid/generator transfer switch. (I've heard some aren't.)
-Would be nice if it can be set to use solar and battery as primary, but include grid to cover the difference if solar and battery aren't enough. (I've heard some can do this, and some can't.)
-Internal AC to DC programmable charger for the battery would be nice.
-Internal MPPT solar controller would be nice.
-It does not need to be able to back-feed the grid.
-It does not need to function as a UPS. (I have those in place already.)

There's lots of You Tube videos out there describing and reviewing various inverters, but none of them answer all of my questions. Maybe I'm not asking the right questions. Beyond the specs, I have concerns about tech support and return policies. Every inverter I've looked at has at least one horror story to go with it. I don't want my inverter to come with free drama. Also, where does one actually buy them? What stores can be trusted? A lot of the brands out there don't sell directly. So suggestions are welcome.

[GoingElectric]

Every inverter I've looked at has at least one horror story to go with it. I don't want my inverter to come with free drama. Also, where does one actually buy them? What stores can be trusted? A lot of the brands out there don't sell directly. So suggestions are welcome.

Failures of devices are mostly often from sized wrong, installed wrong (wrong wiring, no room between parts) and bad mounting (eg: lack of cooling).
Then failure of periodic inspection and maintenance (simple as keeping it clean)

There is a very low chance it is due to manufacturing flaw.

Focus more on features you need and want, and give a good overhead (20% spare capacity? others can say).

[Calsun]

At this point in time getting warranty support for a failed inverter is nearly impossible. I have been trying to get a failed SunPower inverter that failed under warranty in September 2022 replaced and as of today it looks like I may get a replacement in March 2023 at the very earliest.

I bought a Solis inverter for a property two weeks ago and it shipped without the current firmware rev and so is dead on arrival. It has take two weeks just to get an update stick from Solis the may or may not fix the problem. None of their field sales engineers has a clue about how digital devices like an inverter functions and can only go off a script which is nearly always going to fail to detect the cause of a problem. The solid sales engineers failed to understand that the Solis inverter was not retaining the settings in memory and so would never work until that was resolved first. Pretty basic stuff but outside the knowledge of the Solis tech support people.

Many inverters are made by SunnyBoy and then rebranded by other companies like SunPower which makes support even more challenging. The dealers and installers will refer you to the manufacturer who is most likely located in China.

I would recommend delaying any new system installation for at least 4 months as with the current supply shortages and problems are not going to be resolved quickly and you may find yourself with a system that almost works but you will still be paying for the equipment and labor costs regardless.

[rebelrider.mike]

I appreciate the responses. I have found that most things I buy work fine, but then there's the occasional issue with something. I've also got a long and frustrating history with tech support. They either seem to be polite but clueless, or they assume I'm and idiot or a liar (or both). A few companies have been fantastic. But not many.

So the good news is that I probably won't get around to buying an inverter until 2024 at the earliest. This year I hope to install the sub panel and maybe even the backup generator. I've also got several other projects competing for my time this year. Who knows what new products will be out by then? But in the meantime, I hope to get my brain wrapped around all this inverter stuff so I can make a good decision as to which products to buy. It's been an interesting study so far.

[Calsun]

When I priced out the Tesla power wall its cost was the same as for a 16 kW generator. As I have natural gas at my house I went with the standby generator. The Tesla would provide power for at most 48 hours and I have outages that last longer than that. The generator can run virtually forever as in California (unlike Texas) our natural gas supply has never failed to be available.

I installed the generator outdoors and the only issue is the exhaust fumes and so I blocked two vents into the space under the house and I installed a CO monitor inside the living space. With a power bank there is the risk of it catching fire and buring down the house as well as the release of deadly fumes inside the house. The only safe way to install a power wall would be to have an outside cinder block wall built and attach the power wall to it and then run the electrical feeds through conduit.

[GoingElectric]

I appreciate the responses. I have found that most things I buy work fine, but then there's the occasional issue with something. I've also got a long and frustrating history with tech support. They either seem to be polite but clueless, or they assume I'm and idiot or a liar (or both). A few companies have been fantastic. But not many.

So the good news is that I probably won't get around to buying an inverter until 2024 at the earliest. This year I hope to install the sub panel and maybe even the backup generator. I've also got several other projects competing for my time this year. Who knows what new products will be out by then? But in the meantime, I hope to get my brain wrapped around all this inverter stuff so I can make a good decision as to which products to buy. It's been an interesting study so far.

I was thinking of doing one roof (no shadow) with string inverter, but seeing a video listing + and -, going with all micros.

[solar pete]

If going micros get some spares right from the get go it will save mucking around later

[rebelrider.mike]

Microinverters can be a great solution for some systems. In my case, they would lead to extra conversions, and I'd need additional control devices I think, to make them work during a power outage.

I ended up looking at 17 different inverters, and compared 10 specifications of each that I thought were important. A lot of inverter companies don't publish all their specs, so this was rather difficult at times. I was surprised and frustrated to find how many companies refuse to publish the total harmonic displacement of their products. A couple even refused to acknowledge that their inverters had any.

If I were to pick one today, it would be the EG4 6000EX-48HV. It has the most features I'm looking for without having some kind of deal-breaking flaw. I don't need to pick one today, so it will be interesting to see what new products become available in the next year or two.

[Ampster]

.........

If I were to pick one today, it would be the EG4 6000EX-48HV. It has the most features I'm looking for without having some kind of deal-breaking flaw. I don't need to pick one today, so it will be interesting to see what new products become available in the next year or two.

I could not confirm if the EG4 was UL listed if UL compliance is a deal breaker. The UL spec needed in my jurisdiction is UL1741SA. Typically Tier one inverters which comply with that spec cost several times more than the EG4.

[rebelrider.mike]

I couldn't find any UL listing either. I'm pretty sure it doesn't have one. For me, that means I can use power from the grid, but I wouldn't be able to sell power back to the grid. That's ok with me. In my area, a grid-tie system must be shut off completely during a power outage. My primary reason to install any of this stuff is to have backup power during power outages. So a UL listing would be nice, but for me, not having it isn't a deal breaker.

[SunEagle]

I couldn't find any UL listing either. I'm pretty sure it doesn't have one. For me, that means I can use power from the grid, but I wouldn't be able to sell power back to the grid. That's ok with me. In my area, a grid-tie system must be shut off completely during a power outage. My primary reason to install any of this stuff is to have backup power during power outages. So a UL listing would be nice, but for me, not having it isn't a deal breaker.

Remember unless you have batteries any type of inverter will not provide constant power due to shadows (clouds and such) on the panels.

IMO unless you have a grid tied system and selling excess power back to the POCO the best and most reliable emergency back up power source would be a generator of some kind which you will need if you use batteries so you can charge them if the sun isn't shining and the grid is unavailable so why go with a solar/battery system. So look for a UL listed grid tie inverter and go that way.

[J.P.M.]

I couldn't find any UL listing either. I'm pretty sure it doesn't have one. For me, that means I can use power from the grid, but I wouldn't be able to sell power back to the grid. That's ok with me. In my area, a grid-tie system must be shut off completely during a power outage. My primary reason to install any of this stuff is to have backup power during power outages. So a UL listing would be nice, but for me, not having it isn't a deal breaker.

It also means the system probably won't get permitted if one is required.

[rebelrider.mike]

I understand, and rest assured, I'm not buying anything today. Sometime this year I'll be contacting a solar contractor to get a home energy/solar audit. They'll no doubt have a lot to say about permits and approved equipment. They'll also make a list of things I can do to make the house more energy efficient, as well as the size and locations of any solar arrays that might fit my house. Maybe they'll have an inverter available that does all the things I want and have an approved listing.

I'm doing all this research ahead of time so I can ask intelligent questions when I go to the PUD, L&I, and the solar contractor. Oh, by the way, I was browsing my local L&I website today, and it turns out they'll happily accept certifications from a number of different laboratories, besides UL. Of course, the EG4 has none of those either, but who know what will happen over the next year or two?

[Ampster]

The EG4 has a certification from TUV, whatever that is?

[rebelrider.mike]

A product certification company that I'm not familiar with. But my local L&I has them listed as an acceptable certification source. I haven't seen it listed anywhere in EG4's documentation. Where did you find it?