Not Enough SOC in Tiny House

[Doug Wall]

If you're renting it out, the last thing that you want to do is run out of electricity during a 3 day cloudy period (bad reviews would get you kicked out of AirBNB). The combustion heaters only solve part of the problem. You really want to run the burial cable the 200' to the barn for reliable power

 

[chocoheadfred]

lower knee area on LFP.

huh?

 

[chocoheadfred]

If you're renting it out, the last thing that you want to do is run out of electricity during a 3 day cloudy period (bad reviews would get you kicked out of AirBNB). The combustion heaters only solve part of the problem. You really want to run the burial cable the 200' to the barn for reliable power

Thanks and agreed Doug.

 

[740GLE]

Just disclose the tiny house as “rustic” and let the renters know if they don’t conserve energy the lights and heat will go out, you could prob even charge double for those “adventure seekers” looking to “rough it”.

 

[Zwy]

huh?

You have 2 knee areas on LFP state of charge curve. One at the bottom end from about 3.1V down to 2.5V per cell, the other at the high end from 3.5V to 3.65V per cell. It is about the 3.5V to 3.65V per cell knee I'm referring to.

 

[chocoheadfred]

Just disclose the tiny house as “rustic” and let the renters know if they don’t conserve energy the lights and heat will go out, you could prob even charge double for those “adventure seekers” looking to “rough it”.

Funny AND true

 

[corporate.joe]

Not sure, here are the options at my disposal through the online app. Can you see what you need to answer this?

Did you get anywhere with this issue since Jan?



Is that your actual maximum charge current for all sources combined? Go to the Growatt unit and cycle through your settings on the LCD until you get to "02" I believe it is and find out. Your batteries in parallel(or separate) like they are should have no problem charging at the max output of that inverter/charger. The MPPT maxes out at 100amp. Max total for AC and Solar charging together is 100amp. If you want to limit charging current from the AC charger that is setting "11". I would make sure your setting number "02" is at max and limit your AC charging current as needed. Some of these settings might not be adjustable if you have the rs485 from the inverter connected to the BMS and the inverter battery type set to lithium. I might recommend splitting those strings if shading is an issue. If only 1 panel of that 8s gets shaded it really hurts. Not sure where that would put your VOC though.

Looks like your MPPT is following the load with about 1kw above it.



I imagine that sharp climb at 8AM is the sun finally rising above shade and then you hit the reconnect voltage and the inverter and loads cut back on. The rest of those bumps look like charging getting maxed out at 1kw which at 48 volts is... 20amps. But that sharp fall off at noon. Cloud? Shade? Bulk charge voltage limit hit?

Spoiler

I bulk charge my DIY bank to 3.4v per cell. So if I was running 16S I would set that at 54.4v I didn't see any mention of a smart shunt. Do you have one? I don't run this inverter, I'm basing the above off of what I assume is similar to my 24volt growatt 3k lvm not connected to BMS and using USER battery configuration.

That's my two cents.

 

[Abodyofscience]

I'm late to this party but from your graph it seems you are short 2 kWh of storage, for whatever reason.

Cloudy days is another issue.

For seasonal consumption numbers you may need to find the heating degree days and cooling degree days for your area.