12kW system review quicky

[aurfalien]

Allo,
I've had a 6kW setup running rather well consisting of;
Growatt 6kW and 3 Signature Solar 48V batteries. The house runs fine however I'm at or a tad over 6kW at times, wires and fuses getting fairly warm and I've had the inverter shut down now and again.

Not a big deal however I've decided to build a larger unit using Growatts 12kW unit and 4 Signature Solar batteries rather then 3.

As I crimp wires, install fuses/switches etc, I can't help but feel that this is over kill but my calcs show me otherwise.

Based on this;
12000 ac watts / .85 conversion factor / 48 volts low cutoff = 313.725490196078431 service amps
313.725490196078431 service amps / .8 fuse headroom = 392.156862745098039 fault amps
* I will only be using using roughly 7kW at times but am building the system for potential and not the moment.

Using these numbers, I went with 4/0 wire and a 48V/400A class T fuse, massive stuff compared to my 6kW setup which seems like a Tonka Toy at this point.

This time I'd like to use a DC cut off switch between the fuse and battery bank so I bought this;

https://www.amazon.com/dp/B093PFC5JN?psc=1&ref=ppx_yo2ov_dt_b_product_details

Man this stuff seems yooooge, just massive but it's what I'm using.

Is this over kill?
And in terms of the DC cut off switch, would any one have a better recommendation?

 

[SamDeleted]

Big system ! It does seem a bit overkill why do you need so much power all at once

 

[aurfalien]

Big system ! It does seem a bit overkill why do you need so much power all at once

Well I don't but the 8kW inverter was not available at time of purchase. And I like to future proof.

I also didn't use my microwave with the AC on and while I have gas appliances, my oven is electric.

So "if" I had my AC, oven and microwave on at the same time, I would probably even have shut down the 8kW inverter.

With my 6kW inverter, I was a few amps over on 1 leg for a few seconds which shut it down. Most of the time the inverters cooling fans would not even come on which means i was well under utilization.

Picture using say 1,900 watts more or less on average but then my AC, fridges etc happen to cycle near the same time. And I plug in a vacuum cleaner and my wife decides to dry her hair.

However are my wire and fuse properly sized?

 

[littleharbor2]

while I have gas appliances, my oven is electric.

This one item is pretty scary in an Off Grid system. Do you happen to have the stats on it?

 

[aurfalien]

This one item is pretty scary in an Off Grid system. Do you happen to have the stats on it?

Yes I know. Would you like stats on the electric oven?
BTW in off grid or grid down, I would suggest a rocket stove and even a small air fryer in place of a built in electric oven.

 

[littleharbor2]

Yes. I've never looked into, or thought of using, an electric oven. I live off grid. What scares me is that Creating heat with harvested solar power is a very substantial load to have to factor into your system design, especially with the alternatives.

 

[Quattrohead]

1yr old Whirlpool glass top stove watts per burner.
LL - 3300w
UL - 1300w
LR - 2600w
UR - 1300w
Bake - 2600w
Broil - 3500w

 

[aurfalien]

Yes. I've never looked into, or thought of using, an electric oven. I live off grid. What scares me is that Creating heat with harvested solar power is a very substantial load to have to factor into your system design, especially with the alternatives.

So very very true.
I'm certain that you know exactly how much power that you use and how much you need.

The most valuable lesson that I've learned here is how much energy we need for modern living.

 

[aurfalien]

1yr old Whirlpool glass top stove watts per burner.
LL - 3300w
UL - 1300w
LR - 2600w
UR - 1300w
Bake - 2600w
Broil - 3500w

Wow, so say you are doing a turkey and wish to at least bake and at times broil. That means for every hour it's in the oven, you are using at least 2600 watts or about 1/2 of a 48V Signature Solar battery.

So guess crickets are on the menu?

 

[John Frum]

Allo,
I've had a 6kW setup running rather well consisting of;
Growatt 6kW and 3 Signature Solar 48V batteries. The house runs fine however I'm at or a tad over 6kW at times, wires and fuses getting fairly warm and I've had the inverter shut down now and again.

Not a big deal however I've decided to build a larger unit using Growatts 12kW unit and 4 Signature Solar batteries rather then 3.

As I crimp wires, install fuses/switches etc, I can't help but feel that this is over kill but my calcs show me otherwise.

Based on this;
12000 ac watts / .85 conversion factor / 48 volts low cutoff = 313.725490196078431 service amps
313.725490196078431 service amps / .8 fuse headroom = 392.156862745098039 fault amps
* I will only be using using roughly 7kW at times but am building the system for potential and not the moment.

Using these numbers, I went with 4/0 wire and a 48V/400A class T fuse, massive stuff compared to my 6kW setup which seems like a Tonka Toy at this point.

This time I'd like to use a DC cut off switch between the fuse and battery bank so I bought this;

https://www.amazon.com/dp/B093PFC5JN?psc=1&ref=ppx_yo2ov_dt_b_product_details

Man this stuff seems yooooge, just massive but it's what I'm using.

Is this over kill?
And in terms of the DC cut off switch, would any one have a better recommendation?

That switch looks like a cheap knockoff.

Here is a switch that I trust https://www.bluesea.com/products/category/11/35/Manual_Battery_Switches/HD-Series

Will you be using a capacitor pre-charge circuit?

 

[aurfalien]

That switch looks like a cheap knockoff.

Here is a switch that I trust https://www.bluesea.com/products/category/11/35/Manual_Battery_Switches/HD-Series

Will you be using a capacitor pre-charge circuit?

Oh perfect man thank you! I'll get myself that switch. I like their products.
One of the SigSolars battery features is that they have a pre charge cap built in.

EDIT Oh darn, it's rated for 32V, can I use it in a 48V env?

 

[John Frum]

Oh perfect man thank you! I'll get myself that switch. I like their products.
One of the SigSolars battery features is that they have a pre charge cap built in.

EDIT Oh darn, it's rated for 32V, can I use it in a 48V env?

Sorry bout that.
No you should not use that.
I will look some more.
If you are using rack batteries they have a built in means of disconnect and a separate disconnect switch in not required.

 

[littleharbor2]

1yr old Whirlpool glass top stove watts per burner.
LL - 3300w
UL - 1300w
LR - 2600w
UR - 1300w
Bake - 2600w
Broil - 3500w

The high wattage combined with the typical long cooking times and preheating would turn the oven into a storage unit in my place. I use about 5.5 kwh a day here, comfortably, I might add.
Off grid +cook and heat with propane.

 

[aurfalien]

Sorry bout that.
No you should not use that.
I will look some more.
If you are using rack batteries they have a built in means of disconnect and a separate disconnect switch in not required.

No worries, I've emailed there support but don't expect an answer.

 

[John Frum]

Mo worries, I've emailed there support but don't expect an answer.

They always get back to me.
Sometimes it takes a while though.

 

[aurfalien]

The high wattage combined with the typical long cooking times and preheating would turn the oven into a storage unit in my place. I use about 5.5 kwh a day here, comfortably, I might add.
Off grid +cook and heat with propane.

Yea my wife and I are fairly low consumers and I've recorded times of 2,100Watts used per 24 hours.
But it's when we crank up those heat generating appliances is when things get dicy.
Hell, a 12" miter on a big project could be an issue.
The thing with propane is that you can't make it. However with a few panels there is a modicum of decent living available.

 

[littleharbor2]

Yea my wife and I are fairly low consumers and I've recorded times of 2,100Watts used per 24 hours.
But it's when we crank up those heat generating appliances is when things get dicy.
Hell, a 12" miter on a big project could be an issue.

Things like Microwave ovens and coffee makers are doable because of the short duration they are running. I make my coffee and immediately pour it into an insulated carafe. Moral, high draw but short duration, no big deal

 

[SamDeleted]

Well I don't but the 8kW inverter was not available at time of purchase. And I like to future proof.

I also didn't use my microwave with the AC on and while I have gas appliances, my oven is electric.

So "if" I had my AC, oven and microwave on at the same time, I would probably even have shut down the 8kW inverter.

With my 6kW inverter, I was a few amps over on 1 leg for a few seconds which shut it down. Most of the time the inverters cooling fans would not even come on which means i was well under utilization.

Picture using say 1,900 watts more or less on average but then my AC, fridges etc happen to cycle near the same time. And I plug in a vacuum cleaner and my wife decides to dry her hair.

However are my wire and fuse properly sized?

Cable sizing is not my area of expertise ?

Obviously it's up to you! But for me, when off grid I'm trying to use as little power as possible, one 11w LED, we gather round a 10 inch Android tablet for a movie cause they don't use much power. I try to keep consumption as low as possible

 

[aurfalien]

Cable sizing is not my area of expertise ?

Obviously it's up to you! But for me, when off grid I'm trying to use as little power as possible, one 11w LED, we gather round a 10 inch Android tablet for a movie cause they don't use much power. I try to keep consumption as low as possible

Agreed 100%.

 

[Quattrohead]

Wow, so say you are doing a turkey and wish to at least bake and at times broil. That means for every hour it's in the oven, you are using at least 2600 watts or about 1/2 of a 48V Signature Solar battery.

So guess crickets are on the menu?

Once the oven is up to temperature, it will cycle on and off to regulate. Same with the top plates.
So yes if you turned everything on (bake not broil) at the same time you would be pulling 11,100w or 46.25 amps but as the oven got up to temp and your gravy is simmering etc, that draw will go down.
BUT, you have to rate the inverter and battery for that crazy moment when "her indoors" cranks everything on.
Now if she is running the clothes dryer too and its getting warm in the house.....