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EG4 18kPV Round trip Efficiency and overall system efficiency data and calcs

SignatureSolarJames

SignatureSolarJames

Try Solar, the Grid will always take you back
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Location
Sulphur Springs, Texas
Alright guys!

Here is some data about running a whole house off the grid/in self consume mode for several months on the 18k AIO

Battery charge+discharge efficiency is 89.4% for energy stored and used after sunset
daytime efficiency is 97.5%, power coming directly from solar panels to AC output

1683293421893.png


if you click the "battery discharge section it shows "battery charge" aspect. 1683293470605.png
I added the 12kwh on the bank to the battery discharge number for overall totals
1118kWh discharged vs 1250kWh charged
1118/1250kWh = 89.44%

The customer shows 1538kWh of self load 1118kwh of this was at night (demographics is a 2 worker no kids household so the daytime load skews lower than retiree or family day usage ratio) so daytime = 420kWH or only 27% of load

their power co pays $.078/kwh so they exported 2158kWH as well at 97% efficiency, but I will avoid that part as many do not have any serious export value and would not have put in extra solar

this is probably the lowest efficiency possible due to the daytime ratio

89% x 73% + 97% x 27% = 91.1% total system efficiency

I would put this in the inverter efficiency section of PVWATTS when you do your design calcs if you are not a heavy daytime user

MORE SYSTEM ANALYSIS COMING :)
 
Very nice.

Have you been able to verify accuracy of the numbers the inverter is reporting? It has been noted that the Sol-Ark can be a little skewed in its reported values...
 
SignatureSolarJames said:
Here is some data about running a whole house off the grid/in self consume mode for several months on the 18k AIO

Battery charge+discharge efficiency is 89.4% for energy stored and used after sunset
Click to expand...

Good numbers.
Another member (with different equipment) was expecting low 90% based on data sheet but got low 80% range.

Do you have details on the loads driven?
I believe inductive loads and non PF corrected SMPS (like LED lighting) reduces efficiency compared to purely resistive loads like heating elements and incandescent bulbs (or high PF equipment.)

The impact of poor PF on inverter efficiency is largely outside your control, due to I^2R losses in transistors and inductors, I think.
But I'm curious how inverters deal with the phase shift of inductive and capacitive loads, significant AC current not in phase with voltage, rather drawing and returning energy each phase.
 
Hedges said:
Good numbers.
Another member (with different equipment) was expecting low 90% based on data sheet but got low 80% range.

Do you have details on the loads driven?
I believe inductive loads and non PF corrected SMPS (like LED lighting) reduces efficiency compared to purely resistive loads like heating elements and incandescent bulbs (or high PF equipment.)

The impact of poor PF on inverter efficiency is largely outside your control, due to I^2R losses in transistors and inductors, I think.
But I'm curious how inverters deal with the phase shift of inductive and capacitive loads, significant AC current not in phase with voltage, rather drawing and returning energy each phase.
Click to expand...
Would love to try out PF correction devices start a thread maybe?

This was just a whole house which had 17kw of solar (ac rating) installed several years ago
 
It would be good data to gather.
A couple kW of electric radiator heater,
vs. same of LED or compact fluorescent,
vs. induction motor
vs. cheap VFD driving motor
vs. PF corrected VFD

Some mini-split are PF corrected, some are not. Same for PC power supplies.

You may or may not show differences between inverters. Since you carry Schneider and EG, two different architectures as well as brands to compare.

I think the main value would be a guide for customers to understand how appliance selection affects efficiency.
If the "wrong" appliances consume 10% more, may still buy based on price.

The other effect would be total usable wattage, because poor PF devices will overload your inverter sooner.
For instance, my 2HP induction motor pool pump ran fine on 15A breaker. My 2HP VFD powered 3-phase replacement trips 20A breaker.

Here's a thread where I showed AC and DC waveforms.
If you use probes that can measure DC current as well as AC component you can better present what's going on.
The waveforms together with efficiency and maximum power capability would be instructional.
Something @FilterGuy can probably help with?
 
So far I'm not seeing anything close to 91% efficiency - after 260kwh in, at a similar SOC from this starting point, i'm getting like 210kwh out. That's closer to 80% efficient.

I asked @EG4_Jarrett about this and I am wondering if the battery heaters are just running all the time because the t_bat sensor is reporting 2 degrees celsius constantly?

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Is the Tcellmin(C) same as the t_bat? My Tcellmin(C) reads 14C = 57.2 F. And my weather app says it is 59 outside.
 
It would be horrible to have to send that heavy battery back just for a sensor warranty repair. .
 
My data history reads 2 also.
 

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But my cell temps are correct. I don’t know
 

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I just did my efficiency numbers like the example at the beginning of the post. 81% efficiency
 

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OK, so we have the same experience. Cell temps are there, t_bat just says "2", and we're getting about 80% efficiency round trip. Are you comparing roughly the same states of charge in your screenshots?

Also - are you doing a lot of charging from the grid?
 
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