Houston we have problems

[yebbey]

I'm in the Houston area and currently have an Enphase system with IQ8M microinverters. I want to get a battery with all the power outages of late. By my estimate, I need 40 to 50 kwh battery to ensure I can run my house with no interruptions. This would also allow me not to have to draw from the grid at night...almost a fully off grid solution. The Enphase battery is cost prohibitive so I was looking to get the Eg4 18k hybrid inverter along with either the EG4 or Ruixu wall batteries. I'm looking for some advice. Also, if anyone knows if the black start capability would still work outside of the Enphase battery solution. thanks in advance. I've been lurking here for some time, but am a newbie

 

[chrisski]

So, if you are not doing the work yourself, I do not recommend using anything other than what the installer has.

In addition to the battery, you need to figure a Critical Loads Panel, think about 50 amps worth of things, which is a 4 ton AC and a few kitchen devices, Not a single 5 ton AC by itself either. Next you need to get a inverter to AC couple the battery. This probably needs to be planned, permitted, and inspected throughly.

An AC coupled battery is not undoable, just needs a little thought.

I would actually recommend contacting EG4 directly to see their recommendations for an AC coupled system and installer in your area.

 

[yebbey]

thank you. So a little more to think about then. I thought hybrid inverters like the Solark 15k and the EG4 18k would be able to handle the AC coupling. The critical loads panel is to ensure the important things get power if there's not enough left in the battery? Will be contacting EG4. Thanks

 

[chrisski]

thank you. So a little more to think about then. I thought hybrid inverters like the Solark 15k and the EG4 18k would be able to handle the AC coupling.

I went with the Outback, so I don't have specifics on if the two inverters you mention can AC couple. It can be a little more than just hoking the AC in to the generator port. Not sure what those specifics are. outback designed a seperate inverter for this.

The critical loads panel is to ensure the important things get power if there's not enough left in the battery?

The Critical loads panel is

1) What will be powered in case of power outage
2) Can be used for different inverter strategies.
-Where I'm at, the power company lets me use my power I generated for free before I sell to the grid at 1/3rd the rate they charge me.
-Another strategy is to drop the critical loads from the grid so that during peak hours, these loads are ran from the battery. When the battery no longer has enough power, it switches back to the grid. Not sure what happens if the inverter gets overloaded.

There's a bit of thinking that goes in a critical loads panel. I built it for my summer loads where the power consumption is 6 times what it is in the winter. My Critical loads gets nearly full use in the summer with the 4.5 kW 4 ton AC, but in the winter, hardy gets used at all.

Will be contacting EG4. Thanks

This is from the Outback Mojave Manual. I did not go AC Coupled so I did not look at many AC Coupled inverter. If you can do the work yourself with no permitting, than Hybrid may be the way to go, but that would involve disabling the IQ8s.

 

[Lawrence_SoCal]

I thought hybrid inverters like the Solark 15k and the EG4 18k would be able to handle the AC coupling.

correct, they can, as well as non DIY solutions Tesla Powerwall 3 (with upcoming? update), and others

The critical loads panel is to ensure the important things get power if there's not enough left in the battery?

no, not exactly

The issue is your peak kW usage (for me, my local power company provides a 1hr peak usage info on monthly bill). ymmv in terms of whether you know your peak whole house load. Your Solar monitoring may have this info? Or Emporia or other monitoring tool?

that peak load drives 2 considerations
1. - required peak and continuous output of grid forming (black start) hybrid inverter
for some people/houses, the peak load makes for an expensive solution, so to save money on inverter and battery, some folks will do some re-wiring for a subset (critical loads) panel (ie, not power whole house in grid-down situation). There are MANY ways (at different price points, reliability, speed of powering certain devices/circuits down, etc)... so ymmv critical loads panel is just one of many ways to manage load during grid outage. My situation is such that a critical loads panel, when peak usage only in 8kw range, and that includes charging PHEV, is unnecessary. but folks I know in TX, with old Air Conditioners and all electric appliances... different situation
2. - battery capacity to support desired run time for either critical loads or whole house

it sounds like you are planning to power entire house (which is what I'd do, with a fraction of the electricity usage you are trying to cover)
So ask yourself, if grid does down, and no one home and AC running full-blast, and other loads (EV charging?), how would you manage electric load at house? A critical loads panel makes it easy, but not 'smart'. There are various automation methods you could use instead, but some of them won't be instantaneous, which could result in an Inverter overload/trip in just the wrong circumstance (maybe, it depends on your specifics).
recommendation - depends on your exactly peak and high-sustained electric load at your house, your main load center specifics, and what level of sophistication/complexity/reliability you want to manage battery during grid-outage

As alluded to above, I'm fan of whole house solution, BUT that is because my scenario is one where all of the solutions I've looked at would cover my peak continuous usage. If your sustained peak continuous load exceeds (or even near limit) of EG4 18k or similar, then a critical loads panel may be appropriate. OR, get a system that supports higher continuous output (and pay accordingly)? depends on your budget and priorities

 

[yebbey]

Thanks for the input. The attachment shows the highest peak i saw between last summer and this summer. It was a15 min peak at 11.8 kw. It was more of an outlier than norm but if I'm understanding what you were saying then i want to be able to cover that and it seems the eg4 18kpv or solark 15k would both be able to handle it with a rating of 12,000 watts. Am i looking at it the right way?

2 AC units will be the big draws and then washer and dryer. I plan on installing a soft start for the AC.

 

[yebbey]

correct, they can, as well as non DIY solutions Tesla Powerwall 3 (with upcoming? update), and others

no, not exactly

The issue is your peak kW usage (for me, my local power company provides a 1hr peak usage info on monthly bill). ymmv in terms of whether you know your peak whole house load. Your Solar monitoring may have this info? Or Emporia or other monitoring tool?

that peak load drives 2 considerations
1. - required peak and continuous output of grid forming (black start) hybrid inverter
for some people/houses, the peak load makes for an expensive solution, so to save money on inverter and battery, some folks will do some re-wiring for a subset (critical loads) panel (ie, not power whole house in grid-down situation). There are MANY ways (at different price points, reliability, speed of powering certain devices/circuits down, etc)... so ymmv critical loads panel is just one of many ways to manage load during grid outage. My situation is such that a critical loads panel, when peak usage only in 8kw range, and that includes charging PHEV, is unnecessary. but folks I know in TX, with old Air Conditioners and all electric appliances... different situation
2. - battery capacity to support desired run time for either critical loads or whole house

it sounds like you are planning to power entire house (which is what I'd do, with a fraction of the electricity usage you are trying to cover)
So ask yourself, if grid does down, and no one home and AC running full-blast, and other loads (EV charging?), how would you manage electric load at house? A critical loads panel makes it easy, but not 'smart'. There are various automation methods you could use instead, but some of them won't be instantaneous, which could result in an Inverter overload/trip in just the wrong circumstance (maybe, it depends on your specifics).
recommendation - depends on your exactly peak and high-sustained electric load at your house, your main load center specifics, and what level of sophistication/complexity/reliability you want to manage battery during grid-outage

As alluded to above, I'm fan of whole house solution, BUT that is because my scenario is one where all of the solutions I've looked at would cover my peak continuous usage. If your sustained peak continuous load exceeds (or even near limit) of EG4 18k or similar, then a critical loads panel may be appropriate. OR, get a system that supports higher continuous output (and pay accordingly)? depends on your budget and priorities

Forgot the image

 

[Bluedog225]

I was there in Houston with you for four days brother. Rough time. Couldn’t even run a fan.

I think you’re on the right track looking for battery capacity. I’m glad you checked in here because it seems to me that are going to be some cheaper yet still high-quality options for you to connect a large battery bank to your existing system. By cheaper I mean, not Enphase.

I’d recommend you speak to currentconnected.com directly. I would call and talk to somebody in person. You can also reach out to signature solar. A few hours of research here will help you understand the reputation of each company.

As far as how much you need? Running the whole place without interruption as a big ask. I would’ve been happy to run the refrigerator, freezer, lighting, and fans. And maybe, maybe, one inverter style window unit in one of the bedrooms. That would’ve resulted in a pretty pretty comfortable stay with most of the amenities.

@HighTechLab
@SignatureSolarJess

 

[yebbey]

Fortunately my folks live close and they had power but being displaced is not fun.

Hoping for the whole house solution. Working the numbers now. I talked to EG4 yesterday. I will give currentconnected s call today. Thanks for the suggestion

 

[chrisski]

Will you do the work yourself or will you have an installer?

You seem to be on the right path. Even if you use an installer, it will get you closer to him understanding what you're asking.

Recommend seeing if this system has the strategies you want. These are the ones that work for me and what I wish my inverter had.

1) Grid Tied
2) Drop Option to run the critical loads panel off the battery. This I use for peak hours.
3) UPS Mode. If I need to remove power to charge the batteries from the solar mode, all the power dumps to the batteries, but if the grid drops, the batteries take over.
4) Sell Back at certain times. I wish I could set a 3 kW sell back to the grid off the batteries. Since my Tesla charges after peak hours and is not on the critical loads panel, if I set Tesla Charging to 13 amps 240 volts, this 3 kW would be used by the Tesla Charger before it goes to the grid. My current rate plan lets me consume my extra power I produce at no cost to me.

I'm not a fan of whole house backups. I'd be interested in what happens if your system faults out in case of over wattage in a off grid scenario. Mine lacks documentation on that and from the one time it happened, I don't remember if it went back to the "off Grid" or went on grid.

 

[Bluedog225]

Fortunately my folks live close and they had power but being displaced is not fun.

Hoping for the whole house solution. Working the numbers now. I talked to EG4 yesterday. I will give currentconnected s call today. Thanks for the suggestion

Glad you had a place to go. And the weather was more pleasant than it could have been. And fairly sunny.

Imagine this fairly plausible scenario. Big storm. All of houston out. Including your folks.

Cloudy for 7 days. Temps near 100 eff. No wind.

The battery capacity needed for the full meal deal will be extraordinary.

For that scenario, I’d have a look at a natural gas fixed installation generator. Electric and gas going out simultaneously is unlikely in houston absent a tsunami. I think you could get a nice setup for less than $20 grand. May need an upgrade to your meter.

 

[yebbey]

Yeah ..i thought of that too but I'm aiming for one full day of power with hopes that the sun will shine tomorrow. I have a 12kw portable generator and a plug to the breaker(i won't share why i didn't use it, dumb mistake on my part) which i would hook up in that scenario and run the fridge and lights.

The solar buy back rates are getting worse every time i look. Fortunately, in early 2023 i was able to get a 1 to 1 buyback rate outside of an $18 fee. I signed a 3 year contract. That's the other reason i wanted a big battery. Eventually all the plans will be horrible and i want to pull from the grid as little as possible. With this set up i have the option to expand.... Hopefully

 

[yebbey]

I won't be installing myself. At least not the inverter. The batteries didn't seem to be too complicated from what I've watched

 

[Bluedog225]

Sounds like you have a pretty good handle on the variables. I will note that gasoline and propane (tanks) were in short supply. I get about 6 hours on a 20 gallon propane tank with my 9400 watt genny.

 

[SignatureSolarJess]

@SignatureSolarJess

Thank you for the tag!

Definitely reach out if you have any questions for us! If you need me to get you connected with the appropriate team member, please don't hesitate to shoot me a message here or email me at engagement@signaturesolar.com!

 

[yebbey]

Sounds like you have a pretty good handle on the variables. I will note that gasoline and propane (tanks) were in short supply. I get about 6 hours on a 20 gallon propane tank with my 9400 watt genny.

My generator can run on propane or gas. I initially planned on using propane but it doesn't last as long or power as much so i was reconsidering. Gas is always harder to get when the weather events happen. Is propane easier to refill if you already have the tank?

 

[pollenface]

My thought is to put a changeover switch on selected circuits, such as lights, kitchen. A battery bank that charges from your mains power during sunlight hours and an inverter connected to the changeover switches (what i intend to do myself).

 

[Bluedog225]

My generator can run on propane or gas. I initially planned on using propane but it doesn't last as long or power as much so i was reconsidering. Gas is always harder to get when the weather events happen. Is propane easier to refill if you already have the tank?

Yes. Need a tank for refill. Otherwise you have to source one. And power is lower.

Also, once you put gasoline in a genny, you introduce a whole world of ongoing maintenance issues. Lots. And fuel storage issues. Those issues do not come into play with propane or piped in natural gas.

I’ve taped off the gasoline cap on my genny. Just too many problems.

 

[KungFuPanda]

Also in Houston and on the same line of thought. My house is new, 2000sf with a 3.5 ton AC. I'm looking at the EG4 12k or 18k and just wiring it right to my main panel with an interlock kit and taps. Simplest setup, don't plan on exporting, can start peak shaving with a free nights plan and start recouping before even putting up a PV array.

 

[wheisenburg]

With the power of today's inverters they can handle most of the loads in the main panel with no problem. My dual Schneider system can handle surges to 24,000 watts. When no big loads are running my home uses 500-800 watts. So instead of moving some items to a critical loads panel, I added a "Grid" panel to my system. Most of my loads stay in the main panel. No the 7 watt LED light in my closet it not critical, but running it really isn't a problem. If there are high amp appliances that are not critical, they can be moved to the "Grid" panel. For example car chargers, dryers, water heaters, electric ranges and ovens. Dishwashers do have a heating element, so you wouldn't want to run them either when your power is critical.

I added a main disconnect to the system so it can be worked on. The flow through the system is Meter -> Disconnect -> Grid Panel -> Inverters -> Main Panel. I have found that I don't actually need to move anything to the grid panel at this point. I have a 2 ton AC. In the summer I have more than enough energy to run that. I can just not run the wall oven or drier if I am off grid and power is low. If I have full sun, and I actually do want to run the drier, it isn't a problem. So, could I overload the system by turning on every appliance at the same time? Sure, but that is also true of just about any home. If you plug a hair dryer into every outlet in your house and turn it on, what do you think will happen?

Of course loads do need to be managed so you don't run out of power. The ability to top off your batteries with a generator is much cheaper than buying a large amount of batteries. If you have natural gas in your home, get an gas outlet and gen inlet setup (and test everything to make sure it works). For us people that are more north, winter is the most critical time. Nights are long, days are short and our heaters run a lot. They don't require as much power as AC, but production is way less in the winter. The 300 watt fan in the heater will consume about 5 KWHs if it runs all night. That will all need to come from the batteries. In the day, during the summer, my system will generate way more energy than the AC uses, so there is no reason to not run the AC when off grid. If you are in a climate where it stays hot all night, then of course you will either need to limit how much you run the AC at night, or get bigger batteries.

IQ8s had a problem with AC coupling, but Enphase fixed it and they work fine now.