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Any advantage to setup two different models of EG4 inverters in split phase or should they be the same model?

mike23w

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Joined
Feb 19, 2024
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sunny state
TLDR:
Can you configure different models of inverters the EG4 3kW and EG4 6.5kW to provide 240V split phase to power a 240W/24A clothes dryer? My Google search hinted this was possible but it depends heavily on the inverters.
Or is it better to instead use two EG3 3kW inverters for this purpose?


Hi,

I'm out of my element with solar panels, inverters, batteries, electrical concepts especially how to implement split-phase and was wondering if I could get some guidance. This is all new to me.

I also realized my idea is half baked and should probably put this out there and hear what the community has to say and course correct sooner than later.

Let me describe what I'm trying to do.

ELECTRICAL LOADS
I have three main types of electrical loads I'd like the solar panel+inverter+battery system to handle.
  • Load#1 An electric car which is charged each week day and uses 12 kWh per day.
    I don't drive the car on the weekend.
    I'm currently charging the car using 120V/12A each day and this works fine. I'm satisifed with the charging speed even though it's only Level 1@120V.
    Implementing Level 2@240V charging would be nice if it's fairly easy and cheap to setup, but I would be fine without Level 2 charging if it's complicated.
  • Load#2 Clothes dryer. This dryer has these specs: 240V,5600W,24A,60Hz
    The dryer would typically run for one hour (so under 6kwH) only on Saturday or Sunday.
    I would only run the dryer when I'm certain the batteries have enough charge stored (at least 6kWh). I'd never run the dryer from the electrical grid (I can't even do this today because there is only a 120V/30 amp fuse box).
    I don't need to charge the car on weekends since I don't work weekends and there's a second gas car available. This means the car and the dryer would never be use simultaneously.
  • Load#3 Other random electrical loads. These are all small 120V electrical loads: TV, computers, lamps, etc. These would use maybe 1kWh to 3kWh every day. The solar system doesn't need to handle this since these are such small loads, the electrical grid can power these.
    But it'd be nice, if it's simple to implement, to have the solar system power them when there's excess solar/battery capacity that's available.
    If it makes the design simpler, Load#3 can be completely ignored.

THE SOLAR SYSTEM
This is what I have planned so far (I'm mainly interested in powering a dryer @ 240V/24A/5.6kW):
  1. 24 x solar panels @ 305 W for 7.3kW. 12 panels connected to one inverter. 12 panels connected to the second inverter
  2. 2 x EG4 off-grid inverters. 1 x EG4 3kW inverter. Haven't decided on the second EG4 inverter - either the 3kW or 6.5kW inverter (see below for details). Configured in split-phase providing 240V to a dryer. And if it's easy, using 240V to charge the car.
  3. 3 x EG4 5kW LifePo4 batteries @ 15kWh. Unsure how to connect these 3 batteries to the 2 inverters.
    If I absolutely had to, I'd buy a fourth EG4 5kW battery if each inverter needs to have two batteries each but I'd prefer not to spend the money.


OFF-GRID INVERTERS AND SOLAR PANELS
I currently have this EG4 3kW Off-Grid Inverter (5kW PV input, 3kW output).
I was thinking of connecting a dozen 305W solar panels to this EG4 3kW inverter.

I was wondering what I should buy for a second inverter: Maybe this EG4 6.5kW Off-Grid Inverter (8kW PV input, 6.5kW output).
And add another dozen 305W solar panels to this second inverter.
The reason for buying the EG4 6.5kW instead of a second EG4 3kW is that it has larger capacity and it is priced better than the EG4 3kW.

All 24 panels would be from the same manufacturer and same model.
The theoretical output of the 24 panels is 7.3kW but let's call it around 6kW of usable power after losses.

This should be large enough each charge the EV each week day (12kWh) and power the dryer on weekends (6kWh).


BATTERIES
I curently have a single EG4 LiFePower4 battery (48V 100AH/5.1kWh).
I plan to purchase two more of these for a total of 15kWh of battery storage.
On weekdays, I'm hoping the 7.3kW of solar panels can charge the battery each day to around 12kWh to 15 kWh, and use this to charge the car.
I'm fine with using grid power to charge the car when there is no sun (eg rain for several days) so currently am -not- planning to purchase extra battery storage for redundancy/rainy days.


QUESTIONS ABOUT THE SECOND INVERTER
  1. Does it make more sense to buy a second identical EG4 3kW inverter so the two inverters are identical? This would output 6kW and should be enough to charge the batteries which will be used to charge the car on week days.
    Or is there any benefit to buying a refurbished larger EG4 6.5kW inverter that is almost the same price as the EG4 3kW? The price difference between a new EG4 3kW and refurbished EG4 6.5kW is about $200 (which is a small percentage of the total cost of the system). I'd prefer to buy the larger 6.5kW inverter if can provide more capacity.
  2. If the answer to question#1 is get the EG4 6.5kW. Can it be setup to pair with the EG4 3kW to provide 240V split phase to power the 240V/5.6kW dryer, charge the car and sometimes power the smaller 120V loads (ie Load#1, #2 and #3)?
    Again, I do not plan to run the clothes dryer and charge the car at the same time.
QUESTIONS ABOUT CONNECTING THE BATTERIES TO THE TWO INVERTERS
  1. There will be two interters and three batteries. I haven't looked into how to connect the batteries to the two inverters. Can I just have both inverters connected to all 3 batteries?
    Or does one inverter connect to one battery and the second inverter connect to two batteries?
    Or do I need to connect two batteries each to one inverter?


THINGS I HAVEN'T FIGURED OUT: 30 Amp Fuse Box
The house has an ancient 80 year old 30 amp fuse box (ie uses old-school screw-in fuses) which I'd like to have an electrician replace at some point with a 100A modern breaker panel. This is going to be fairly expensive depending on how I go about it so probably won't be done in the next year.
If the fuse box was replaced with a modern breaker panel, I still do -not- want to connect the solar system to the breaker panel to implement grid-tie (and feed excess energy back to the grid) because it doesn't seem worth it hence the decision for the solar system to be off-grid.

The two inverters would, however, be plugged into two regular 120V electrical outlets so it can draw power from the grid when the panels and batteries are depleted for charging the car and small electrical loads (ie load#1 and load#3).

Today, the 30 amp fuse box is actually large enough to power all of the loads in the house - it charges the car and run the smaller loads fine (ie load#1 and load#3). There is also currently a small 120V clothes dryer that's being run from the 30 amp fuse box but this takes over an hour to dry clothes which is why I'd like to switch to a new larger 240V dryer (mentioned in load#2).

The solar system would never be used to run the 240V dryer from the grid because today because it simply cannot do this with the 120V/30a fuse box.
But If a modern 100 amp break panel is installed, I'm not sure whether the solar system can be modified to take advantage of this increased power from the electrical grid. Could I have a couple of 240V outlets and just plug the two EG4 3kW and/or 6.5kW inverters into these?


Sorry for the long newbie post. It's my day off, had some time and wanted to see if anyone might have thoughts about these plans.

I'm not looking necessarily for a detailed design, but more whether my overall approach seems somewhat reasonable. If I'm doing something completely dumb I'd like to know :). Thanks!
 
Sorry, I didn't read it all. Or really any of it (sorry). But based on the subject, I'll put in my two cents. EG4 imports inverters, it is not a manufacturer. Don't count on any comparability between different models, they may come from different manufacturers.

Your battery to PV ratio is off. No where near enough battery for most situations that have 7kW of solar.
 
TLDR:
Can you configure different models of inverters the EG4 3kW and EG4 6.5kW to provide 240V split phase to power a 240W/24A clothes dryer? My Google search hinted this was possible but it depends heavily on the inverters.
Or is it better to instead use two EG3 3kW inverters for this purpose?


Hi,

I'm out of my element with solar panels, inverters, batteries, electrical concepts especially how to implement split-phase and was wondering if I could get some guidance. This is all new to me.

I also realized my idea is half baked and should probably put this out there and hear what the community has to say and course correct sooner than later.

Let me describe what I'm trying to do.

ELECTRICAL LOADS
I have three main types of electrical loads I'd like the solar panel+inverter+battery system to handle.
  • Load#1 An electric car which is charged each week day and uses 12 kWh per day.
    I don't drive the car on the weekend.
    I'm currently charging the car using 120V/12A each day and this works fine. I'm satisifed with the charging speed even though it's only Level 1@120V.
    Implementing Level 2@240V charging would be nice if it's fairly easy and cheap to setup, but I would be fine without Level 2 charging if it's complicated.
  • Load#2 Clothes dryer. This dryer has these specs: 240V,5600W,24A,60Hz
    The dryer would typically run for one hour (so under 6kwH) only on Saturday or Sunday.
    I would only run the dryer when I'm certain the batteries have enough charge stored (at least 6kWh). I'd never run the dryer from the electrical grid (I can't even do this today because there is only a 120V/30 amp fuse box).
    I don't need to charge the car on weekends since I don't work weekends and there's a second gas car available. This means the car and the dryer would never be use simultaneously.
  • Load#3 Other random electrical loads. These are all small 120V electrical loads: TV, computers, lamps, etc. These would use maybe 1kWh to 3kWh every day. The solar system doesn't need to handle this since these are such small loads, the electrical grid can power these.
    But it'd be nice, if it's simple to implement, to have the solar system power them when there's excess solar/battery capacity that's available.
    If it makes the design simpler, Load#3 can be completely ignored.

THE SOLAR SYSTEM
This is what I have planned so far (I'm mainly interested in powering a dryer @ 240V/24A/5.6kW):
  1. 24 x solar panels @ 305 W for 7.3kW. 12 panels connected to one inverter. 12 panels connected to the second inverter
  2. 2 x EG4 off-grid inverters. 1 x EG4 3kW inverter. Haven't decided on the second EG4 inverter - either the 3kW or 6.5kW inverter (see below for details). Configured in split-phase providing 240V to a dryer. And if it's easy, using 240V to charge the car.
  3. 3 x EG4 5kW LifePo4 batteries @ 15kWh. Unsure how to connect these 3 batteries to the 2 inverters.
    If I absolutely had to, I'd buy a fourth EG4 5kW battery if each inverter needs to have two batteries each but I'd prefer not to spend the money.


OFF-GRID INVERTERS AND SOLAR PANELS
I currently have this EG4 3kW Off-Grid Inverter (5kW PV input, 3kW output).
I was thinking of connecting a dozen 305W solar panels to this EG4 3kW inverter.

I was wondering what I should buy for a second inverter: Maybe this EG4 6.5kW Off-Grid Inverter (8kW PV input, 6.5kW output).
And add another dozen 305W solar panels to this second inverter.
The reason for buying the EG4 6.5kW instead of a second EG4 3kW is that it has larger capacity and it is priced better than the EG4 3kW.

All 24 panels would be from the same manufacturer and same model.
The theoretical output of the 24 panels is 7.3kW but let's call it around 6kW of usable power after losses.

This should be large enough each charge the EV each week day (12kWh) and power the dryer on weekends (6kWh).


BATTERIES
I curently have a single EG4 LiFePower4 battery (48V 100AH/5.1kWh).
I plan to purchase two more of these for a total of 15kWh of battery storage.
On weekdays, I'm hoping the 7.3kW of solar panels can charge the battery each day to around 12kWh to 15 kWh, and use this to charge the car.
I'm fine with using grid power to charge the car when there is no sun (eg rain for several days) so currently am -not- planning to purchase extra battery storage for redundancy/rainy days.


QUESTIONS ABOUT THE SECOND INVERTER
  1. Does it make more sense to buy a second identical EG4 3kW inverter so the two inverters are identical? This would output 6kW and should be enough to charge the batteries which will be used to charge the car on week days.
    Or is there any benefit to buying a refurbished larger EG4 6.5kW inverter that is almost the same price as the EG4 3kW? The price difference between a new EG4 3kW and refurbished EG4 6.5kW is about $200 (which is a small percentage of the total cost of the system). I'd prefer to buy the larger 6.5kW inverter if can provide more capacity.
  2. If the answer to question#1 is get the EG4 6.5kW. Can it be setup to pair with the EG4 3kW to provide 240V split phase to power the 240V/5.6kW dryer, charge the car and sometimes power the smaller 120V loads (ie Load#1, #2 and #3)?
    Again, I do not plan to run the clothes dryer and charge the car at the same time.
QUESTIONS ABOUT CONNECTING THE BATTERIES TO THE TWO INVERTERS
  1. There will be two interters and three batteries. I haven't looked into how to connect the batteries to the two inverters. Can I just have both inverters connected to all 3 batteries?
    Or does one inverter connect to one battery and the second inverter connect to two batteries?
    Or do I need to connect two batteries each to one inverter?


THINGS I HAVEN'T FIGURED OUT: 30 Amp Fuse Box
The house has an ancient 80 year old 30 amp fuse box (ie uses old-school screw-in fuses) which I'd like to have an electrician replace at some point with a 100A modern breaker panel. This is going to be fairly expensive depending on how I go about it so probably won't be done in the next year.
If the fuse box was replaced with a modern breaker panel, I still do -not- want to connect the solar system to the breaker panel to implement grid-tie (and feed excess energy back to the grid) because it doesn't seem worth it hence the decision for the solar system to be off-grid.

The two inverters would, however, be plugged into two regular 120V electrical outlets so it can draw power from the grid when the panels and batteries are depleted for charging the car and small electrical loads (ie load#1 and load#3).

Today, the 30 amp fuse box is actually large enough to power all of the loads in the house - it charges the car and run the smaller loads fine (ie load#1 and load#3). There is also currently a small 120V clothes dryer that's being run from the 30 amp fuse box but this takes over an hour to dry clothes which is why I'd like to switch to a new larger 240V dryer (mentioned in load#2).

The solar system would never be used to run the 240V dryer from the grid because today because it simply cannot do this with the 120V/30a fuse box.
But If a modern 100 amp break panel is installed, I'm not sure whether the solar system can be modified to take advantage of this increased power from the electrical grid. Could I have a couple of 240V outlets and just plug the two EG4 3kW and/or 6.5kW inverters into these?


Sorry for the long newbie post. It's my day off, had some time and wanted to see if anyone might have thoughts about these plans.

I'm not looking necessarily for a detailed design, but more whether my overall approach seems somewhat reasonable. If I'm doing something completely dumb I'd like to know :). Thanks!
You might add a split phase SINGLE 6KW minimum inverter (may require battery voltage of 48VDC) Your battery will take a big hit,(6KWH) to run your dryer load. Run dryer load only close to peak of 7KW PV array to defer some battery demand.

Comment to ignore small 1-3KWH loads and let the grid handle it, WHY?. Solar by nature LOVES those kind of soft, regular predicable loads of convenience. Why not connect those to your solar system and DITCH THE GRID.

So, here is the down and dirty two cents I will offer.

If LOAD #2 Dryer is really your load of concern AND you are satisfied with Level 1 EV charger (or Level 2 at a less than full capacity), then concentrate on the 6000W load and maximize your system to that load. You could even pick up LOAD#3 convenience loads (NOT during the LOAD #2 run time) and ditch the grid. You really should look at your battery capacity being boosted above 20KWH or greater total capacity to take advantage of your PV array. You mentioned nothing about the PV array or charge controller other than 24 panels at 305watts. Are they parallel connected, series connected, both? Are they oriented correctly for long-lat and angle of your location? Check for PV effectiveness while doing this upgrade to maximize your solar collection.
 
You can't parallel off grid inverters unless they are designed to be parallel.

You can parallel on grid, but only one should have batteries. If you want to run them when grid is down, then the inverter without batteries should be ac pv into the inverter with batteties. If the inverters do not support that, then don't do it.
 

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