Can you just confirm the scenario where no grid power is available and PV input (1500Watts) is available while AC output is connected to loads (1200Watts).
Is it:
the whole 1500Watts are stored in the batteries while 1200Watts are being pulled from the batteries for AC out?
-1200 Watts from PV input are directly inverted and supplies to AC (bypassing battery charge/discharge) and the remaining 300 Watts are injected in the battery?
First scenario would be a poor use of batteries (conversion loss + wear) while the second one is in line with our expectations (off-grid UPS).
I’m unpleased to see the FAQ for both AC200P & Max no longer mention the following - it used to be item #5 back in June this year:
Q5: Can I charge and discharge AC200P at the same time?
A: Yes, but it is not recommended to charge and discharge at the same time in order to protect the battery life.
Now only AC200Max has a mention of it: « Can I charge and discharge at the same time? Yes. »
I’d like a clear confirmation that PV IN doesn’t continuously charge the battery in off-grid situation where appliances are running 24/7. Would defeat the purpose of being a UPS.
Sadly for you the previous FAQ was clear about this: just-in-time PV consumption still involves battery charge & discharge prior to feeding AC out.
I think bluetti documents that ups is only available when grid power is available. Pass through is a ups feature. So if you are not in ups mode, with grid power being up, there is no ac pass through. I think that pv charging is dc power in and not ac power in so that ac pass through on dc power in isn’t there/possible since dc must be inverted to ac and cannot pass through since it is not original ac in.
I don’t think the ac300 runs like a growatt or sol-ark. I think the pv in power must be stored on the battery first then ac is inverted from the storage available and not directly through pv in.
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%.
