First Solar-System check

[EROWATOM]

This is my first post!
I just bought this ECO-Worthy kit and plan to install it in my garage running a fridge and freezer totally off grid.

Over the last few days I had a power consumption meter connected and it turns out, the fridge and the freezer combined use a mere 1.6KWh per day. I understand it is winter in SoCal, but even if the consumption doubles, this system should be enough.
And worst case scenario, the Hybrid Inverter also has a Grid hookup as a backup. Though at the moment I am not planning on using it.
I am pretty good with my electrical stuff, but I had 2 questions:
- Do I need to add a fuse anywhere? Maybe 150A between battery and inverter? And/or a 20A or 25A breaker between the inverter and the outlets?
- Do I need to ground the system? If so, how? Can I just extend the ground wire from a nearby grid-tied outlet? Or do I need a ground rod?
I asked these 2 questions to the techsupport at ECO-Worthy and they said:
- no additional fuses are needed.
- for grounding I should just connect the housing of the inverter to the ground terminal of the inverter.
That just does not sound right to me. Specifically the grounding: I mean I would expect that the housing of the inverter is already connected to the ground terminal internally.
Anyway, I am interested in what the smart people in here have to say.

 

[littleharbor2]

Pretty sure your watt numbers on the fridge and freezer are incorrect. Just as an example, my 14 cu. ft. fridge draws about .75 amps @ 115 vac when running. This is 86.25 watts. If you are going by the numbers on the fridges data label that may be the max power rating, which is likely when in defrost mode, when a brief heating cycle is running.
As to the freezer, their total power draw is usually less than fridges, due to better insulation and less frequent openings.

 

[Mattb4]

I would add a fuse and a DC breaker between battery and AIO. It might not be necessary to have a breaker on your AC outlet but it can be not a bad idea if you have a distribution box feeding several items. Ground should be attached to the AIO's chassis ground. You could grab this from your house ground. Or, as you were told, you can jumper the incoming AC ground to the chassis ground. On these inverters I have found that they do not have a good internal connection for earth grounding otherwise.

 

[EROWATOM]

Pretty sure your watt numbers on the fridge and freezer are incorrect. Just as an example, my 14 cu. ft. fridge draws about .75 amps @ 115 vac when running. This is 86.25 watts. If you are going by the numbers on the fridges data label that may be the max power rating, which is likely when in defrost mode, when a brief heating cycle is running.
As to the freezer, their total power draw is usually less than fridges, due to better insulation and less frequent openings.

Thanks for the feedback! I am pretty sure my watt numbers are correct. My power consumption meter shows exactly that: about 500W usage when the freezer is running, 750W when the Fridge is going and about 1250WW when they are both running. the meter even shows historic low (3.5W) when both are in standby and high (1275W) when they are both on. Maybe I should mention, the fridge is a full size side by side that you would find in most kitchens in the US.
But again, the good news is that they combines only use 1.6KWh a day.

 

[EROWATOM]

I would add a fuse and a DC breaker between battery and AIO. It might not be necessary to have a breaker on your AC outlet but it can be not a bad idea if you have a distribution box feeding several items. Ground should be attached to the AIO's chassis ground. You could grab this from your house ground. Or, as you were told, you can jumper the incoming AC ground to the chassis ground. On these inverters I have found that they do not have a good internal connection for earth grounding otherwise.

Thanks Matt, that's what I thought...
As for the fuse sizing, does a150A RV breaker sound right to go in between the battery and the AIO?
And 20 or 25 A for the AC side?
Thanks.

 

[Mattb4]

Fuse from the battery of 150a would work. On your AC out from the AIO it would depend on the wire size and also if you are going for max power 3000w/120vAC = 25a which likely your operators manual specifies 30a. All of the recommended wire and fuses sizes should be in manual.

 

[littleharbor2]

Thanks for the feedback! I am pretty sure my watt numbers are correct. My power consumption meter shows exactly that: about 500W usage when the freezer is running, 750W when the Fridge is going and about 1250WW when they are both running. the meter even shows historic low (3.5W) when both are in standby and high (1275W) when they are both on. Maybe I should mention, the fridge is a full size side by side that you would find in most kitchens in the US.
But again, the good news is that they combines only use 1.6KWh a day.

Something doesn't sound right. Your fridge and freezer would have to be running only about an hour and a half every 24 hour period to only consume 1.6 kwh. Very strange.

 

[chrisski]

-2S3P panels would normally require fusing. Normally is once the max series fuse ratign is exceeded. Never seen 3P of panels not needig this fusing.

-What are the input parameters for the MPPT? Totally unaware of yor AIO specs. Some require 60 volts to wake up, 2S panels gets you 40 volts.

-A single 100 ah battery ith 100 amp output can only provide 2400 watts of power prior to tripping the BMS. What the spin up is for your compressor, I don't know, but I see how if both kicked on at once potential to trip the BMS. For example powering the system up.

-With the 100 amp limitation for a 3000 watt system, I'd recommend 200 ah of battery. I have a similar system, just bigger battery: 3000 watt inverter with a 24 volt system and 560 ah of battery.

-For grounding, I have this in an RV and it is grounded per instruction manual to the frame of the RV. I can't speak to grounding, but I'd look at how construction is done in your area.

-The AC outlet should have an electric breaker.

 

[DVD]

I would add a fuse and a DC breaker between battery and AIO. It might not be necessary to have a breaker on your AC outlet but it can be not a bad idea if you have a distribution box feeding several items. Ground should be attached to the AIO's chassis ground. You could grab this from your house ground. Or, as you were told, you can jumper the incoming AC ground to the chassis ground. On these inverters I have found that they do not have a good internal connection for earth grounding otherwise.

Agreed in all regards

 

[EROWATOM]

Fuse from the battery of 150a would work. On your AC out from the AIO it would depend on the wire size and also if you are going for max power 3000w/120vAC = 25a which likely your operators manual specifies 30a. All of the recommended wire and fuses sizes should be in manual.

In regards to the wire sizes... they included two 4AWG battery cables (red and black). Isn't that too small? Or is it OK because they are only 36 inches long?

 

[EROWATOM]

-2S3P panels would normally require fusing. Normally is once the max series fuse ratign is exceeded. Never seen 3P of panels not needig this fusing.

-What are the input parameters for the MPPT? Totally unaware of yor AIO specs. Some require 60 volts to wake up, 2S panels gets you 40 volts.

-A single 100 ah battery ith 100 amp output can only provide 2400 watts of power prior to tripping the BMS. What the spin up is for your compressor, I don't know, but I see how if both kicked on at once potential to trip the BMS. For example powering the system up.

-With the 100 amp limitation for a 3000 watt system, I'd recommend 200 ah of battery. I have a similar system, just bigger battery: 3000 watt inverter with a 24 volt system and 560 ah of battery.

-For grounding, I have this in an RV and it is grounded per instruction manual to the frame of the RV. I can't speak to grounding, but I'd look at how construction is done in your area.

-The AC outlet should have an electric breaker.

Yeah, you are probably right with the battery size... 200Ah would be better... but hey, I got to have something I can look forward to upgrading...
BTW, the MPPT of the AIO is 30-85VDC (100V max open voltage).
I was wondering if the supplied solar hookup cables are big enough... what is the min AVG I should use?

 

[CaliSunHarvester]

Your fridge and freezer would have to be running only about an hour and a half every 24 hour period to only consume 1.6 kwh. Very strange.

I measured our big French door fridge with 2 freeze compartments.. over a week. Average per day was 1.5kWh with a full family including children under 12 = frequent door opening.

1.6 for 2 units is possible if they don't get opened too often

 

[Mattb4]

In regards to the wire sizes... they included two 4AWG battery cables (red and black). Isn't that too small? Or is it OK because they are only 36 inches long?

Yeah it is bit light for a 3kW inverter. 2 AWG would be better if the distance is short. That is about the max size you can fit reasonably into the access hole at the AIO. If your batteries are further distance than a few feet you might consider placing you disconnect breaker close with 2 AWG to AIO and then 1-0 to the batteries.

 

[chrisski]

Yeah it is bit light for a 3kW inverter. 2 AWG would be better if the distance is short. That is about the max size you can fit reasonably into the access hole at the AIO. If your batteries are further distance than a few feet you might consider placing you disconnect breaker close with 2 AWG to AIO and then 1-0 to the batteries.

I’m not sure a 2 AWG has the wire ampacity for a 3 kw 24 volt inverter. If 2 AWG is the max size for the receptacle, I’d be worried about using this unless the wire had a very high temperature rating.

I wonder how many amps a 24 volt inverter draws at full load to include an 85% inverter conversion loss?

 

[littleharbor2]

I’m not sure a 2 AWG has the wire ampacity for a 3 kw 24 volt inverter. If 2 AWG is the max size for the receptacle, I’d be worried about using this unless the wire had a very high temperature rating.

I wonder how many amps a 24 volt inverter draws at full load to include an 85% inverter conversion loss?

It's like they think we all use only the high temp. silicone jacketed wire like they use on BMS's

 

[Mattb4]

It can get complicated understanding battery cable sizing. Since type of insulation, length and where installed all play a factor in overall ampacity ratings. Below find from Temco there welding wire ratings.

 

[Mattb4]

...

I wonder how many amps a 24 volt inverter draws at full load to include an 85% inverter conversion loss?

For the 3kW unit in question 3000w/24v=125a Allowing for loss would put that at 147a

 

[chrisski]

It can get complicated understanding battery cable sizing. Since type of insulation, length and where installed all play a factor in overall ampacity ratings. Below find from Temco there welding wire ratings.

View attachment 189462

That chart allows a lot more amps than the one I use. I wonder if that is 105 C rated wire?

I've also wondered if maximum amps is the same thing as ampacity.

 

[EROWATOM]

That chart allows a lot more amps than the one I use. I wonder if that is 105 C rated wire?

I've also wondered if maximum amps is the same thing as ampacity.

The supplied wire is 105 C rated. Quite flexible for its size too.
And yes, ampacity is just a funny way of saying amp-capacity, aka max amp... meant to comment on that earlier
I thought the length of the wire also plays into that topic. Does anybody have a table that shows ampacity as a function to cable length?

 

[Mattb4]

For welding cable the chart here: https://www.directwire.com/resources/welding-cable-ampacity-chart/#jumptoampacitychart gives some ideas. but it does not allow for enclosed areas and also voltage drop. Many of the charts you find on line are not terribly helpful other than as a starting point.

Remember you have to use round trip cable length.