Roof Solar - Best Inverter?

Background
Hi all,

I'm rather new to the solar field and certainly new to the DIY solar and how many options there are. I've spoken with a few big box solar installer and learned they're all scams and only local installers are worth anything, but even then they take around $0.9-1.0/watt installed, dramatically increasing the cost of the total system compared to DIY.

In my case I have a house in Texas that I want to have back up power during outages and solar to lower energy costs and tell centerpoint to kick rocks. I need to power at least a 3-ton AC unit with LRA of 84 and RLA of 14. Gas stove, water heater, and furnace, so those aren't going to draw power. But I will need something that has at least some overhead after that air con unit. I also use around 11,000kWh a year of energy, and peak at 3.3kW in a single hour.

One of my biggest questions relies on the inverter. I will likely be moving in 4-5 years (no sooner, I'm in a medical training program) and was interested in the mobility of the EcoFlow Ultra unit, however for my purposes, I would also need the smart home panel 2, plus the batteries are very expensive for this unit. This raises the cost of a 12kWh battery plus SHP2 plus inverter to 8k without installation.

I then came to the EG4 6000XP or 12kPv or 18kPv. These, while immobile, would allow for more throughput, though the 6000XP may not be enough, and I may require either two 6000XP or the 12kPv or 18kPv. Ideally, I'd have 12kWh or so of battery (or more since more is better lol). I'd also expect around 5-7.5kW of solar on the roof, though this depends on cost.

This leads me to the other issue, the cost. I am willing to pay a modest premium simply for the peace of mind of an auto switch system to avoid power outages compared to having to use a generator (I know there's auto generator systems, but that would raise the cost to be close enough to solar that the reduction in electrical bill from solar would outcompete the generator).


Questions
Anyways, my main questions are here:

1. Is this feasible? I've been reading a lot on this forum and am mixed on whether the system I want to design is truly feasible and beneficial to me compared to just buying a cheap generator and having to set it up anytime the power goes out.

2. If Solar is feasible and better, then what is your recommendation on batteries and solar production for someone looking to relatively minimize the financial investment and desiring a quicker return on investment period (I understand I may not entirely hit break even if I move a little early, but the increase in value of home with solar plus the peace of mind, if another power outage occurs, will likely take care of that difference, if its 3k or less).

3. Which inverter is best for my situation? Can the 6000XP manage? Is somehow the ecoflow ultra actually the best? Or should I go with the 12kPv?
I'm struggling to find any actual direct documentation on what these inverters can handle, a boon to the ecoflow is it clearly states what LRA it can support.

4. If you have any tips for which solar panels I should install or if there's a way to integrate everything better, or heck, just anything including warnings or something better I haven't thought of, then please let me know.


I really appreciate all the knowledge on this forum and have been reading for a while. I've read all sorts of reviews on the EG4 systems and sadly am still unsure about which is best for me, hence the post.

Thanks,
Wiz.

The 6000 XP is an of grid inverter and can't switch back to the grid.

By far, the generator will be cheaper for power outages. It's hard to put a dollar amount on it, but a solar setup built to match a generator will cost 10 times to 20 times what a genratator will. That's not a lot of gas saved in power outages.

Reality Wizard said:

3. Which inverter is best for my situation? Can the 6000XP manage? Is somehow the ecoflow ultra actually the best? Or should I go with the 12kPv?
I'm struggling to find any actual direct documentation on what these inverters can handle, a boon to the ecoflow is it clearly states what LRA it can support.

Click to expand...

Reality Wizard said:

In my case I have a house in Texas that I want to have back up power during outages and solar to lower energy costs and tell centerpoint to kick rocks. I need to power at least a 3-ton AC unit with LRA of 84 and RLA of 14. Gas stove, water heater, and furnace, so those aren't going to draw power. But I will need something that has at least some overhead after that air con unit. I also use around 11,000kWh a year of energy, and peak at 3.3kW in a single hour.

Click to expand...

I think you would be happy with a 6kW - 8 kW inverter that is grid tied. I have an outback radian, and this will do what you're asking including starting the 3 ton AC. The surge power will be a lot, around 18 kW, and many inverter you see that are rated for that are only for a cycle or less of power, so you need an inverter that is a beast for start up.

The 3.3 kW requirement can be handled by a lot of inverters, but using an older AC with a LRA of 84 is going to force you to uch higher than you need. Even with a soft start, you probably don't have the power to start the 3.5 ton.

Also need to look at what this overhead is. I found some extra appliances on my critical loads list I hadn't planned for that I need to watch my overhead does not exceed 8 kW constant.

chrisski said:

By far, the generator will be cheaper for power outages. It's hard to put a dollar amount on it, but a solar setup built to match a generator will cost 10 times to 20 times what a genratator will. That's not a lot of gas saved in power outages.

Click to expand...

That's not what I have found.

My parents wanted backup power for hurricane season. One option was a propane powered generator of about 15 KW. Total installed cost, including the tank and wiring, was about $25K.

We are putting in a 12 KW solar array with 28 KWH of battery with a critical panel. The batteries will have 3-4 days of energy in a grid down situation (not everything in the house is powered). If the sun shines at least somewhat during that time, they can go potentially weeks if not indefinitely. When the grid is up, the solar array will pay for itself (they get 100% net metering). Total cost is going to be about $20K and it will pay for itself in about 5-8 years.

No generator can touch the economic value of a solar array because the array generates power all the time for basically free and the generator hardly ever generates power and it is way more costly than the grid.

chrisski said:

I think you would be happy with a 6kW - 8 kW inverter that is grid tied.

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Considering the new inexpensive hybrid inverters in the 10 KW class that sell for under $3K, might as well go for that and have ample power headroom. You can always add more panels and batteries to them as you power needs expand or are better understood. Texas gets a lot of sunshine, so your system performance will be decent.

For 11,000 KWH per year in central Texas, you need an array of about 8 KW assuming it can face south with proper slope. You would need a battery capacity of about 60 KWH to survive two days of no sun, which is pretty big. If you conserve energy during outages (say no AC, dryer, stove), a smaller battery would go a long way.

You will need soft start to run your 3.5 ton AC unit. A bigger inverter is less likely to have trouble doing that. If you only run AC when on grid, then that is no issue since the grid will pick up the load the inverter can't handle.

Mike C.