AC300 Solar Power Distribution

Product Discussion BLUETTI AC Series
1

Hello Everybody,
I am about to purchase the AC300 system (when a good sale occurs). But how I plan on using it will vary based on how the AC300 controllers distribute power from the Solar Panels TO the batteries AND distribution to other items drawing power. I’ll try to keep it simple by using examples.

(Prefer Only using Panels and not connected with the AC input).

Scenario A)
If my panels are suppling 2000 watts/hour and I have 200 watts/hr draw from the AC Port(s) at all times. I am assuming that 1800 watts would be directed to charge the batteries and 200 watts would be used to power the connected devices. Am I correct?
or
Does 2000 watts go to charge the batteries and the connected devices drawing 200 watts/hr pull the power directly from the batteries? I would like to prevent the batteries from being used at all in that situation.

Scenario B)
The Panels in the above situation are only supplying 1000 watts/hr, and there is a power draw of 1000 watts/hr. Does the AC300 distribute all 1000 watts of the Solar Power to provide power to the connected devices and NONE to the batteries OR does the AC300 controller(s) split the distribution of 500 watts to the 1000 watt power draw and 500 watts to the connected batteries and the other needed 500 watts is pulled from the batteries. I know it would not make sense that the latter would occur, I just want to be sure, in case I connect to the AC grid power. I wouldn’t want the AC grid to kick in until the Power draw > than the power supplied by the solar Panels or if the battery power < a certain percentage.

Also, I understand there are many settings that you can control some of it, such as, only use AC Grid power if Battery charge < a certain %.

I would like to find a happy medium to use as much power draw using solar panels AND charge the batteries to capacity each day without using AC grid power, at all. How the solar power is distributed may determine the total batteries for me to purchase (planning 3), also.

I will be using 3 x 450 watt panels per leg of Solar Input which would probably give me a good 2200 watts+ for a large percentage of the day (5-8 hours).

If anyone knows more details of Solar power distribution of the AC300’s controllers, that would be helpful.
William

2

Hello wtytke,
Your questions are very reasonable. However the design of portable power stations is less complicated than you imagine.

The following devices are directly connected to each other, in a “T” relationship:

  1. DC output of the chargers (solar or external grid charging block)
  2. Lithium battery
  3. DC input of the inverter

Here’s a drawing, meant to depict the “T” relationship. (Ignore the ,.,.,.,.,.,.,.,.,.,.,.,., lines, which are needed for formatting.)

CHARGER ------------------ INVERTER
,.,.,.,.,.,.,.,.,.,.,.,., |
,.,.,.,.,.,.,.,.,., BATTERY

Power does not flow “through” the battery—the battery can only charge or discharge. In Scenario A, 200 W flows from charger to inverter to load, and the battery accepts the excess power available (1800 W). In Scenario B 1000 W flows from charger to inverter to load, and the battery is neither charged or discharged.

Your use case appears to involve continuous operation of the AC300. I would not assume that Bluetti products are designed and tested for that scenario. Does any of their marketing describe that use case? You should read another thread on the topic of continuous operation.

4

Thanks @LandLocked, that’s what I thought, just wanted verification, in case it may be different.

My main use was to run my power needs for my backyard AND have the peace of mind to act as a backup power supply for my fridge and freezer if in a power outage. Also, I like the idea that it can be somewhat portable and able to charge a B300 battery on the go with its own panel while the main AC300 and other batteries continue to work in situ.
Yes, I do plan to use it 24/7 to run a 200watt pond pump, but with 3 x B300 batteries that would barely run down at night 200w x 16hrs (3200 watts). In the daytime, I would use the excess energy generated to charge electronics, once the B300 batteries are charged up. In this case the batteries should always be at least 50% by morning and charge back up to 100% during the day.
This AC300 setup, although premium $$$ has more flexible options for me compared to a more permanent LV6548 + rack batteries.
I only have enough space for 6 x 450 watt panels, as I do not want them on my roof. And that works perfectly for my setup.
HOWEVER, if anyone thinks that this setup would not work for what I am planning, I would like to know why. I understand the 3000 - 5000 battery cycle degradation to 80%/50% and panels running down to 80% in 20 years (I could always purchase NEW batteries in 10 years,(if Bluetti is still around). With the 26% fed tax credits ending soon, I thought now would be a perfect time to jump onto the solar ship.

5

wtytke, you probably already know this, but I’ll say it anyway for the benefit of other readers …

The calculation of battery energy used to run the pond pump overnight should include two “overhead” terms:

  • “standby” power: power consumed by the AC300 with inverter enabled and zero load.
    Bluetti manual is silent, but AC300 owners estimate this at 35 Watts.

  • inverter efficiency: AC power produced divided by DC power consumed.
    AC300 specs say this is >88%.

Thus, a more accurate calculation of the battery energy consumed by the pump running for 16 hours would be:

(35W + 200W/0.88) * 16 hour ~= 4200 Watt-hours

.

6

Have you estimated monthly energy production for your solar panel system (at your location and panel orientation), e.g. at PVWatts Calculator or Calculate How Much Solar Do I Need?

7

Note that inverter efficiency depends on the load on the inverter. At low power levels (like your pond pump), efficiency is typically much lower. See https://www.e-education.psu.edu/eme812/node/738 for a “typical” efficiency curve. (In this example curve “standby” power is part of the efficiency plotted, rather than a separate term. That’s why the curve screams down at near zero power. )

The “88%” Bluetti spec is surely the peak efficiency. Your 200W load is only 7% of the 3000W rating on the inverter, so efficiency in your energy calculation may need to be far lower than the spec.

Ideally, you can find an existing AC300 who can run an experiment—200W load running overnight—so you have actual data on energy consumed.

8

Yes, I understand the running of the inverter consumes wattage (I noticed that with my EB55 when the AC button is “left on”) - thank you (I should have mentioned that for others, especially us newbies)/ I was unsure of the energy cost of the AC300 inverter, but that was why I chose to go with 3 vs 2 Batteries. Still, I would be at usually > 40% to 50% battery power (And, yes, I do know that 10% of the 3072 watts of each battery is set for reserve protections).
Also, I have looked at the energy production at my location, angles to set panels @ time of the year, etc. The way I look at it is based on space, cost, of available solar panels (which I have already ordered). Also, I may have exaggerated the 16 hrs of battery use. My Daylight hours based on time of the year is still > 10hrs (Tampa area) at shortest day so, about half of that for decent energy production from the panels I really like that the AC300 has TWO legs, so that I can create 2 mini (adjustable angle) solar arrays that face slightly different directions (morning to 5pm and the other leg 10am - sunset). Also, I understand that cloudy days interfere with ALL the formulas, but that usually only happens with a tropical system or a stalled front at my location (but the AC300 has the Ac Power input to provide power during those days).

But to keep topic of my discussion, I was hoping that my panels produce the 200 watts asap in the morning, and as the day continues, the excess wattage charges up the batteries to 100%, and as the day subsides, the panels produce the 200 watts to the latest time, possible, thereby, reducing reliance on battery usage. Which is why I asked my question concerning that draw on the inverter takes precedence over the charging of the batteries.

1 Like
9

Oh and one more question, If I use a pump that runs on the 24 Vdc output (like this one: https://tinyurl.com/y7ck5nvb ), can I set the AC inverter in the AC300 to be only active in a specified time period? (e.g. daylight 10am-5pm?)

I have noticed that I can charge almost ALL my usb home electronics, including USB batteries on the EB55 in DC mode only (USB Ports) and essentially no charge is drawn from the unit. As soon as I use AC, I do notice a significant power draw.

If I can set the AC inverter on/off time schedule, I can arrange certain items to be plugged in and run during daytime periods only. But I don’t see that in the AC300 manual.