how much inverting power would you need to run your whole house 100% of the time

OzSolar said:

You might also ask people to detail if they are all electric or not.

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Yes, that’s very important detail. We are 4 bedrooms, 3 bath, 3,700+ sq feet. Totally off grid for a year in July. Not even close to running out of battery. 4 mini splits with our original traditional central (split) a/c system which has propane heat, ac is not used but heat is in winter when mini splits can’t keep up. Since mini split installation our peak load never gets over 10kW and rarely exceeds 6kW unless convection oven and/or dryer running. Have one 11.4kW grid forming inverter with another ac coupled to it for the additional battery capacity.
IMO, investing in mini splits to replace (or retire in place) traditional air conditioning systems is an important and cost effective part of being successful off grid with large homes in the south.

We also have propane tankless water heater.

teal95 said:

20 kW of panels, 60 kWh of batteries and now that we've hit A/C season it's not keeping up. It doesn't help that it's hitting 90 every day (with 75 dew point) but cloudy with thunderstorms that keep popping up. Yesterday we got less than an hour of sun.

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You have a big whole house A/C? We had the same problem to solve. During the day we have plenty of solar to run all the loads including the A/C. The problem was - how to run the A/C at night? We have is a 5 ton system and it is old - either on or off, can't ramp power like the new inverter units. Running it from 7PM to 7AM would use 72kwh of power and need probably 100KWH of battery storage. That was crazy. We still run it during the day from solar, but at night we switched to a small mini split in the bedroom. It uses around 1,000 when everything is in max - lowest temp, max fan. On low it only uses 350 watts. So over night it uses 4kw instead of 72 kwh. The downside of that is that the rest of the house is a bit warm in the AM especially if it was a 110F day before. We can live with that. The temp difference is a lot more noticeable because the mini split is so efficient. Air coming out of it is 41F. Air from house A/C vent is 61F - 20F warmer. Bedroom gets to "freezing temps" like in the 50's, so going into the rest of the house in the morning at 80F feels really warm, but not uncomfortable. It works so well that I am considering getting 1 or 2 other mini-splits. They use way less power and do a better job at cooling maybe because of the fact that they also don't have to send air through ducts in the attic that is 130F during the day. Plus if it 1 breaks, it is $1,000, not $8,000 for a whole house unit. Forgot to say - the mini-split is super quiet. Even with fan at max you can sleep at night it it on.

MajicDiver said:

Yes, that’s very important detail. We are 4 bedrooms, 3 bath, 3,700+ sq feet. Totally off grid for a year in July. Not even close to running out of battery. 4 mini splits with our original traditional central (split) a/c system which has propane heat, ac is not used but heat is in winter when mini splits can’t keep up. Since mini split installation our peak load never gets over 10kW and rarely exceeds 6kW unless convection oven and/or dryer running. Have one 11.4kW grid forming inverter with another ac coupled to it for the additional battery capacity.
IMO, investing in mini splits to replace (or retire in place) traditional air conditioning systems is an important and cost effective part of being successful off grid with large homes in the south.

We also have propane tankless water heater.

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I could not have said it better myself! You never know til you try. I am considering the same thing - when the old unit "goes" replace with mini-slits.

1201 said:

hmm. good point . I have a 40 gallon too and in the winter its my highest load. it does feel like its always coming on lol. youve got me thinking maybe I should switch the elements to 2.5kw from the 4.5 kw currently

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Probably a bad idea, tank is too small, recovery time is too slow. While I really don't think an electric demand unit is a great idea with solar, you want it to heat back up fairly quickly. As the cold water pushes in the bottom of the tank more aggressive heating stretches the amount of useful hot water at the faucet. I keep mine up at 140 for a little more buffer. Probably get away with the smaller element this time of year, but I go back to the lifestyle thing. I don't want solar to make me change my lifestyle significantly.

The EV switch turned out to be a stunningly good idea to control demand at least here for us. High hot water demand generally doesn't correlate with drying laundry. The hot water used for washing is more than sufficiently covered by the tank and any gaps between dryer loads. I'll eliminate the box at some point just because I can.

With solar, if I had more hot water demand, I'd put it a bigger tank, but I think 40gal is sufficient for up to maybe 4 people.

You can get variable speed high efficiency central air compressors. There is a reason we got rid of window units and went to central air conditioning and heating in homes. A mini-split is more efficient, but it pigs up wall space, and doesn't vent into storage rooms and bathrooms and ... That lifestyle thing again.

1201 said:

thats very interesting. you must have some good load management. I use 30-40kwh a day for most of the year but my daily demand is around 10kw peak



I have friends who try to keep their texas house at 63 in the middle of summer when its 110 degrees outside, in their 5000 sq ft house. yes, that bill is HIGH!

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Everything bar our chest freezer is low power or has an inverter the 3 AC units typically each draw less than 700w at peak, our big fridge averages 70w when the compressor is on or 2w when it's not and I'm yet to check the well pump

ksmithaz1 said:

The EV switch turned out to be a stunningly good idea to control demand at least here for us.

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Can you regulate EV as variable load?

Talking with another member who expects to be pushed onto NEM 3.0 shortly (as I do), regulating EV charger to achieve zero import/zero export measured with CT should keep bills down.

To operate off grid, it could utilize limited inverter capacity.

Disclaimer: I currently work for a Carrier distributor in IT. I read things and talk to sales droids so I happen to know about these units. It is without a doubt the best one on the market, at least, as long as you don't ask the Trane guys about theirs, or the ...

Every major HVAC vendor has a variation of these units, Trane, Goodman, etc. This is the future of Central air and will put the likes of MicroAir out of business at some point. Technology just keeps rolling along. Somehow people think the technology of a mini-split only exists in a mini-split. The big SEER advantage is the elimination of the ducting, but you stuff 20 mini-splits in your house, in 10-15 years you have 20 problems instead of one. Just don't fall into a trap, a mini-split can be a huge win as well depending on the application, but again, there is a reason we didn't stick with window units which are also more efficient.

So Carrier for example. . .



Mini-splits are attractive because of the cost, but they ain't the same as central air conditioning.

Hedges said:

Can you regulate EV as variable load?

Talking with another member who expects to be pushed onto NEM 3.0 shortly (as I do), regulating EV charger to achieve zero import/zero export measured with CT should keep bills down.

To operate off grid, it could utilize limited inverter capacity.

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Depends on the charger I know it's common on commercial chargers now but I'm guessing consumer ones would use it as a selling point there's lots of home assistant users I've seen with their chargers integrated but haven't seen much in load management.

1201 said:

no ac? in what part of the world? in texas no ac can mean death

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If you don't die, you simply wish for it.

ksmithaz1 said:

View attachment 223333

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I would love to have an inverter based, throttling, central air unit, if combined with a zoned controlled blower with ducts. Talk about living the dream!

ksmithaz1 said:

The EV switch turned out to be a stunningly good idea to control demand at least here for us. High hot water demand generally doesn't correlate with drying laundry. The hot water used for washing is more than sufficiently covered by the tank and any gaps between dryer loads. I'll eliminate the box at some point just because I can.

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what type of ev switch is this ? and how is it wired? sounds interesting

ksmithaz1 said:

You can get variable speed high efficiency central air compressors. There is a reason we got rid of window units and went to central air conditioning and heating in homes. A mini-split is more efficient, but it pigs up wall space, and doesn't vent into storage rooms and bathrooms and ... That lifestyle thing again.

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I used ducted mini splits. I think if I had to do it again I would use ductless that way every room can set its own ideal temp and an empty bedroom can have the ac turned off.

My bathrooms and storage are not conditioned- I think thats a USA thing

Hedges said:

Can you regulate EV as variable load?

Talking with another member who expects to be pushed onto NEM 3.0 shortly (as I do), regulating EV charger to achieve zero import/zero export measured with CT should keep bills down.

To operate off grid, it could utilize limited inverter capacity.

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Not with this box, it's just a priority switchbox designed to tap the Dryer plug in a garage so you can put an EVSE on the same circuit. I just re-purposed making my HWH the EVSE to control demand.

I use an openEVSE that has a fully programmable EVSE unit with a bunch of API's for that functionality. I think chargepoint has units that perform in a similar fashion. I just bang the web API from my stuff.

1201 said:

just curious what everyone's peak demand is and how much it would take to be completely on inverter.

for me the highest demand I've ever had was 19.8kw so I can confidently say that I could run my whole house "off-grid" with 20kw of inverting power.

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Interesting question. Depends. During the day our Sunny Boys can handle all the loads. But we also have to balance the loads with production in order to not export. Sure, if you do nothing and run everything all at once you could use all that is in your 200A panel. For us max is usually less than 50% of that i.e. 20KW. But if the inverters are producing that, net to the grid is more or less 0. It changes at night if we switch to Sunny Islands. Then the max we could do is 12kw. practically speaking 3-5 kw is reasonable for us. When every house is their own power company, you generally have to do things a bit differently. Balance the loads to meet production, have enough storage to meet night time demand, etc. So you can get by with a "smaller system." For a 200A service you will probably not need inverters capable of supplying 48KW continuously.

ksmithaz1 said:

Disclaimer: I currently work for a Carrier distributor in IT. I read things and talk to sales droids so I happen to know about these units. It is without a doubt the best one on the market, at least, as long as you don't ask the Trane guys about theirs, or the ...

Every major HVAC vendor has a variation of these units, Trane, Goodman, etc. This is the future of Central air and will put the likes of MicroAir out of business at some point. Technology just keeps rolling along. Somehow people think the technology of a mini-split only exists in a mini-split. The big SEER advantage is the elimination of the ducting, but you stuff 20 mini-splits in your house, in 10-15 years you have 20 problems instead of one. Just don't fall into a trap, a mini-split can be a huge win as well depending on the application, but again, there is a reason we didn't stick with window units which are also more efficient.

So Carrier for example. . .

View attachment 223333

Mini-splits are attractive because of the cost, but they ain't the same as central air conditioning.

Click to expand...

Links like "Technical Specifications" and "Owner's Manual" don't even list operating voltage, much less power factor.
Is this PF corrected? Makes a difference on how much load it represents for our inverters.

1201 said:

no ac? in what part of the world? in texas no ac can mean death

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My, my, all those people in the 19th century dropping like flies all over Texas. The undertaker would have been busy if he hadn't died from heat stroke. I hope this was a bit tongue in cheek. People today are so effing spoiled. Air conditioning for the masses has not been around that long in the grand scheme of humanity.

Just so we are clear. Excessive heat is rarely fatal unless you are stupid, though never underestimate peoples stupidity. As long as you have water and adequate ventilation you will be fine. OTOH cold kills people silently and slowly. The powers that be have recently changed the way they count heat related deaths to pump up the numbers to fit a certain narrative. Even with that cold by far kills orders of magnitude more people than heat, but for some reason that gets played down.

1201 said:

what type of ev switch is this ? and how is it wired? sounds interesting

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There are plenty ~ $200.

Hedges said:

Links like "Technical Specifications" and "Owner's Manual" don't even list operating voltage, much less power factor.
Is this PF corrected? Makes a difference on how much load it represents for our inverters.

Infinity® 26 A/C With Greenspeed® Intelligence | 24VNA6

24VNA6

www.carrier.com

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It's 240v for sure. Next time I'm in the office I'll hit up one of the engineering tech support folks to see what we have, not really my area. I logged into our customer web portal, but it's all around sales and ordering not documentation.

ksmithaz1 said:

My, my, all those people in the 19th century dropping like flies all over Texas. The undertaker would have been busy if he hadn't died from heat stroke. I hope this was a bit tongue in cheek. People today are so effing spoiled. Air conditioning for the masses has not been around that long in the grand scheme of humanity.

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texas was not as warm then as it is today. i would be interested in knowing what percentage of texas today has no ac.

ksmithaz1 said:

There are plenty ~ $200.

Amazon.com

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wow, very nice. awesome. thanks

Power factor is rarely shown in documentation but it's a very good point that I haven't even considered when sizing the inverter for my home, I have power factors on all my meters around the house maybe I should implement some code to show me accurate figures.

ThaiTaffy said:

Power factor is rarely shown in documentation but it's a very good point that I haven't even considered when sizing the inverter for my home, I have power factors on all my meters around the house maybe I should implement some code to show me accurate figures.

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power factor is only a consideration for small loads right? Ive found the large loads like water heater and dryer, oven etc usually have a power factor near 1.

cs1234 said:

I would love to have an inverter based, throttling, central air unit, if combined with a zoned controlled blower with ducts. Talk about living the dream!

Click to expand...

1201 said:

power factor is only a consideration for small loads right? Ive found the large loads like water heater and dryer, oven etc usually have a power factor near 1.

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As I said In my earlier post everything in our home as far as larger loads have inverters, which all suffer from lower power factors so it's very relevant to the overall peak power my house consumes.

ksmithaz1 said:

My, my, all those people in the 19th century dropping like flies all over Texas. The undertaker would have been busy if he hadn't died from heat stroke. I hope this was a bit tongue in cheek. People today are so effing spoiled. Air conditioning for the masses has not been around that long in the grand scheme of humanity.

Just so we are clear. Excessive heat is rarely fatal unless you are stupid, though never underestimate peoples stupidity. As long as you have water and adequate ventilation you will be fine. OTOH cold kills people silently and slowly. The powers that be have recently changed the way they count heat related deaths to pump up the numbers to fit a certain narrative. Even with that cold by far kills orders of magnitude more people than heat, but for some reason that gets played down.

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It's possible that air conditioning has evolved a race of coddled babies that would now die without it. We are not our ancestors.

The biggest reason I care about power factor is I saw that the poor PF of a VFD upset my AC coupled Sunny Boys, when VFD and Sunny Boys were on an island grid formed by Sunny Island.

If I had not observed the errors (which occurred when Sunny Boy woke up while VFD was supplying pool pump), after repeated errors it would have locked as a permanent error and bricked the Sunny Boy.

For people with an AIO, low PF is just going to cause lower efficiency, higher heat production in the inverter and BMS, limiting usable wattage.


A small load with poor power factor won't matter, overpowered by the grid-forming inverter.
A large load with poor power factor (like multiple HP VFD) is going to clip the tops off sine wave voltage.

Or an army of small loads, like many LED lamps or computer power supplies (some are PF corrected, some aren't.)
I visited an X-box factor 20 years ago, with many units powered on for testing, put a scope to the AC line and saw clipped tops.