Unfortunate because it involves useless battery wear (store and pull energy at the same time).
One battery cycle = having pulled 100% of the battery capacity, in B300 terms that’s roughly pulling 3kWh. It also means 2 baskets of laundry in an average washing machine.
In a previous version of their FAQ, Bluetti recommended against storing and consuming battery energy at the same time (AC200P) due to resulting excessive wear. Given they recommended against it, I want to make sure AC300 is engineered as a “real” solar UPS: invert DC to supply AC loads then only store the excess DC in.
A Victron / Growatt / etc. as mentioned would only store the excess and keep battery wear to its minimum. They are “real” solar UPS devices. I want to make sure AC300 is as “real” as these are.
Even though 3000 cycles is a lot, I just don’t think it’s a good idea / choice to treat a device like a solar UPS while in reality it causes useless wear (+ energy loss due to battery in & out).
About your mention of becoming suspicious, I encourage not to go to that extent quite honestly. I want to trust their reputation first. After all, 3000+ cycles is a lot. Let’s think of it this way: 3 cycles per sunny day means 80% battery capacity is still available after 3-4 years. We purchase a product that has proprietary wires. We know that when an AC300 dies (the inverter and MPPT are the two weakest links in solar generators) then the B300 either needs a new AC300 OR it goes to the bin.
We’ll keep in mind that we buy a product that has 2 years warranty whereas Victron / Growatt / etc wall-mounted devices have 5 to 10 years warranty.
The only Bluetti product with 5 years warranty is EP500pro.
I’m patiently waiting for @BLUETTI 's answer regarding the “solar ups vs battery wear” question.
I agree with you 100% @BLUETTI please come and enlighten us…
Meanwhile I have decided to do a 3rd setup victron based. Although I started out buying 2 sets of 1xAC300 + 4xB300 for emergency/backup power, I decided to try todo maximum off-grid now.
If there is AC load connected when PV is charging, it can be inverted directly through the bus bar without going through the battery.
When the battery is fully charged and the PV is charging, turning on the AC load will not have any effect.
The APP shows the animation demonstration, the actual internal circuit can be directly inverted output if there is AC load connected during PV charging.
@BLUETTI , With the AC300, when there IS an AC Load, if the batteries are at 100% you mention that there isn’t any effect (assuming bypass of the battery); however, the APP shows an animation with NO PV entering (e.g. 0 watts), as long as the battery is at 100%, therefore it appears that the AC Load IS running off the batteries. When the Battery level goes to 99%, then the PV kicks back in until it reaches 100% and back and forth between 99% and 100%. I didn’t know if this situation is a limitation of the App. In my example photos (below) I would expect at least 235W + wattage used by the AC300 inverter to be displayed on the PV input. (also note, after 23 minutes I just had the 100% drop to 99% and is now charging via the PV)
@BLUETTI The number 2 point you have stated does not appear to be accurate in practice as the PV input stops accepting power when the battery reaches 100%. Please see the screenshots @wtytke has provided above. There is ~1.7KW coming in continuous via solar, but the AC300 does not accept it until the battery storage drops to 99%. This indicates repeated cycles of drain and charge cycle on the battery storage even when steady power is available via PV input. I am seeing the same behavior he has documented here.
A cycle is supposed to represent a 100% discharge/charge operation. So SOC changing between 99% and 100% continually would add up a to a single cycle after 100 occurrences. In some input/load/storage ratios these 1% cycles could add up to a complete cycle in under a day.
@BLUETTI It would be preferable if PV input was not shut off for AC and DC output and only prevented from topping the battery when SOC reaches 100%.
Hi @stumped , The machine supports charging and discharging at the same time, you can connect an AC port load.
The power generated by the PV will be given to the load and can also be divided a little to charge the battery. You have this question should be you do not connect the load device.
We suggest that you can connect a 1600W load, the PV can be utilized. The machine does not turn off the AC and DC output, it just turns off the charging input, because the battery cannot be overcharged, it is fully charged when it reaches 100%.
@BLUETTI, what @stumped and I am trying to say that when there is an AC and/or DC Load and the batteries are at 100% and the PV INPUT power is GREATER than the AC & DC load then the load should be powered 100% by THE PV INPUT and NOT the batteries.
Asking the question another way – WHY is the PV Cutting off completely when there is an AC (or DC) Load to power?
Can’t the MPPT direct the excess PV power to JUST THE LOAD and NOT the Batteries when the batteries are fully charged?
Asked even another way – When the batteries are at 100% , and there is an AC (and or DC) Load, AND there is more than significant PV input, then the PV excess power should BYPASS the fully charged batteries, and then power the AC Load WITHOUT using the batteries, at all.
Almost everything I read on MPPT’s in general will redirect the excess solar input to the Inverter and shut off the power to the batteries when they are full (float). The batteries will only begin to be utilized if the PV input is lower that the AC Load + Power to run the Inverter, such as a cloud passing by.
That is not how the AC300 is behaving, I would like to know why, besides the excuse to protect the batteries. The MPPTs in the AC300 should do that AND direct “opportunity loads” to the inverter, thereby passing the batteries.
Bluetti could easily double the life of the battery (at least in my case) if the batteries were not constantly being drained.
The AC300 user manual is inaccurate. Where it mentions pass-through in the FAQ it should say “limited pass-through” and then detail that when the batteries are fully charged pass-through does not apply for AC and DC outputs.
This is a serious limitation and had the Bluetti documentation been accurate I likely would not have purchased.
