EB70S Parallel Solar Panels?

Frankly i’m disappointed that the larger ones are still limited to 500W AC.
The competition can handle around 1500W AC (so can the AC300).
Why is the AC200MAX limited to 500W AC?

I mean, to be totally fair, a lot of it could also be battery life related. The faster you cram in the charge, generally (at least on LiPos for my drones) the faster you wear out the batteries. I’d imagine we could also be seeing some of that here as well, trying to optimize the cycle life on the cells?

Given the AC input voltage is fixed at 58.8V the limit of 500W is likely due to how many amps the input circuit can accept by design, which is 8.5A. The DC input for solar is capped at 900W for a combined 1400W total which is very formidable given the 2000Wh internal battery capacity.

then why is the AC300 far less limited?
Is it because the B300 can accept at 80A (according to the B300 manual) so up to 5000W?

Yes, the AC input port of the AC300 is a lot more capable at 3000W than the AC200Max’s 500W. It’s less limited because it’s a bigger and better performing product. You will need a special 30A AC charging cable to charge the AC300 at the full 3000W which needs to be plugged into a NEMA L14-30 outlet.

The 80A is describing the maximum amps that can be passed through the B300 battery expansion port either for charging or discharging. An AC300 will utilize up to 51A when discharging 3000W via the inverter and the full 80A when charging via combined AC and DC input ports (5000W).

This is still lying to the customer and the wider marketplace, precisely because the claim is not realistic when using typical solar panels. Regulators don’t let car manufacturers claim extremely high gas mileage on their vehicles that are achieved through extreme driving techniques. They have to claim MPG according to standardized protocols that attempt to measure MPG in (arguably) realistic and comparable ways.

As much as people complain about government regulation, it is shady marketing practices like this that spur calls for industry regulation.

I concur. But as someone in this thread alluded to earlier, a 200 watt 12 volt panel may generate the 8.5 amp maximum input of the EB70 (approx. 150 watts for typical panels) even when weather and time-of-day are less than ideal. I.E. connecting solar panel(s) rated at 12 volts / 200 watts to an EB70 may be the ideal even if the EB70 can’t ever receive more than 8.5 amps.

Ultimately this is about how long it takes to recharge the EB55 and EV70. Bluetti could come clean about this by spelling it out more clearly.

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Thanks for clarifying this, “Admin”.

To a beginner like me, who knows nothing, when I read a specification that says:

OCV:              12-28 VDC
Input Current:       8A Max

I have no way to know that the OCV specification cannot be exceeded without possibly damaging the Bluetti Power Station or tripping an overvoltage condition, while the Input Current specification can be exceeded with no harm to the device. I suggest editing the specifications in your documentation, i.e.:

OCV:            12-28 VDC*
Input Current:     8A Max**

*  Exceeding PV Input of 28 VDC may damage your Bluetti portable power station
   and, for voltages exceeding ___ volts possibly pose a fire risk.

** The input current may exceed 8 amps; however, your Bluetti 
   portable power station will only receive up to the maximum 
   input current specified.

I’d go even further, by stating:

A typical 12 volt 200 watt panel (or pair of 12 volt 100 watt panels) will 
exceed the Bluetti power station's 8 amp input current maximum under peak 
conditions.  The Bluetti portable power station will only receive up to the 
8 amp input current  limit.  But having typical solar panels with current rating
above 8 amps is still beneficial, as these panels can generate more amps over
a longer period of the day, under less-than-ideal solar conditions, than typical
solar panels rated at exactly 8 amps of current.

And finally, claiming Input Power of “200W Max.” is deceptive when most 200 watt 12 volt panels can’t do this while staying under the 8 amp max current threshold. Better to claim 150W Max Input power for typical panels, then add an asterisk to state that 200 W Max Input is possible when using panels capable of sustaining 25 volts without exceeding the 8 amp input current limit.

What really makes me kinda wince is at the same time, over-voltage will, from other folks’ experiences right here, destroy the entire thing with no protection at all. So it makes the top end not only technically difficult to reach, but also dangerous from the sense of a high potential to fry your unit entirely!

I concur. Safety should be priority #1 for this market, especially since it is aimed at the D.I.Y. crowd rather than trade professionals. These products need some kind of over-voltage protection to mitigate the risk of damage or even fire. The following $30 device might be suitable for protecting EB55/EB70 power stations:

SVR1000 Single Phase Protection Relay Over-Voltage 20V-80V Under-Voltage 0.1V-30V AC/DC(AD48)

As for over-current protection, I can’t tell from the EB70S manual whether that is built-in, or whether it is critical to add a fuse between the power station and the solar panels. I intend to add a fuse, but I am not sure the proper rating (10 amp, or 15 amp) to place between an EB70S and a Renogy RSP200D-US 12 volt 200 watt panel.

There’s also no discussion of earth grounding in the manual. Needed? if so, where on the chassis is the ground screw?

From what I understand, there is no over-current risk, the unit will draw only what it needs. Over-voltage, there simply is no protection of significance, or if there is, it is very small and easily overwhelmed. The “max voltage” marking at the port is the protection for these units, it seems.

There is some wiggle room with the over-voltage before it permanently breaks the input circuit. Maybe around 10-20% over? For my EB3A (rest in pieces) I could input 32V and it didn’t explode and would continue working fine with < 28V afterwards.

Edit: Fixed typo

I wonder how much of that is actual legit over-voltage protection, and how much was just using up the design tolerances in the components, though. There doesn’t seem to be any kind of active protective system or even a first-stage replaceable failure point to protect the charge controller. If you want to get close to the actual charge rate listed, you’re going to have to push dangerously far up the voltage scale, with an input source that varies madly based on changing environmental conditions.

I’m in the same boat as Komitadjie. I’m new to solar and recently purchased an EB70S and am now I’m looking for the best panel to pair with it and quickly realized I wasn’t going to be able to get close to 200W maximum solar charging limit with a 200W panel because of the 8A input limit. I got to thinking about the possibility of using a larger panel such as a 250w panel that has a little bit higher VMP.

The panel below is 250w panel and makes 250w at 23.83V and 10.51A. The EB70S will only pull 8A. Vmp 23.83 at 8A is 190w. With that said I’m guessing as the amps decrease so does the voltage, but I really do not know. Is there a way to calculate what the actual voltage would be with this panel at 8A?

https://www.newpowa.com/collections/rigid-solar-panels/products/250w-monocrystalline-solar-panel

PRODUCT CODE NPA250S-15I
Maximum power (Pmax) 250W
Voltage at Pmax (Vmp) 23.83V
Current at Pmax (Imp) 10.51A
Open-circuit voltage (Voc) 27.28V
Short-circuit current (Isc) 11.09A
Temperature coefficient of Voc -(80±10)mV/°C
Temperature coefficient of Isc (0.065±0.015)%/ °C
Temperature coefficient of power -(0.5±0.05)%/ °C
NOCT (Air 20°C; Sun 0.8kW/m² wind 1m/s) 47±2°C
Operating temperature -40°C to 85°C
Maximum system voltage 1000V DC
Power tolerance ± 3%
Maximum series fuse rating 15A

Two things:

  1. The open-circuit voltage of this panel is 27.28V which is extremely close to the max voltage input on your EB70S of 28V. It will increase beyond this in winter - at which point you should not connect it unless you’ve certain it is safe my measuring the open circuit voltage of the panel with a multimeter before plugging it in.
  2. Once the power station starts pulling amps from the panel, the voltage will decrease from the Open-circuit voltage to the voltage at Pmax of 23.83V (the describes the voltage when you are pulling the maximum amount of power). It could of course decrease further. In other words, the higher the amps, the lower the panel voltage.

Safely using this panel you may well be able to get very close to the 200W max, do let us know!

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Yeah, my concern would be the high-end voltage range, we’ve seen demonstrated a fair number of times that there is very, very little if any over-voltage protection on the incoming side - and if there is, we haven’t gotten any definition of what it will mitigate and where it will catastrophically fail. We know 60V will go past the catastrophic failure point, but how much over that was? We don’t know.

If you do get it over 160W or so, for sure let us know! I’d LOVE to be able to actually charge mine at the rate that they advertise.

I see what you mean about potentially exceeding the max input voltage with the Newpowa 250w panel in cold weather. Does Bluetti publish any safety margins to the 28v max input? Just wondering if there is, for example, a 5v safety margin or something like that?

Newpowa does have a 240w panel with the following specs. This panel would give me a little more of a safety margin before hitting the 28v max. What do you guys think of this panel? It might get me a little closer to 200w.

# PRODUCT CODE # NPA240S-15I
Maximum power (Pmax) 240W
Voltage at Pmax (Vmp) 23.16V
Current at Pmax (Imp) 10.40A
Open-circuit voltage (Voc) 26.71V
Short-circuit current (Isc) 10.97A
Temperature coefficient of Voc -(80±10)mV/°C
Temperature coefficient of Isc (0.065±0.015)%/ °C
Temperature coefficient of power -(0.5±0.05)%/ °C
NOCT (Air 20°C; Sun 0.8kW/m² wind 1m/s) 47±2°C
Operating temperature -40°C to 85°C
Maximum system voltage 1000V DC
Power tolerance ± 3%
Maximum Series Fuse Rating 15 A
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With 32V PV input my EB3A would not accept the voltage (the Input label would blink) but it doesn’t break the input circuit. I think just below 29V was the highest the MPPT controller would start pulling amps.

It’s all a balancing game. The closer you want to get to the 200W max input, the closer you have to get to the 28V max voltage input. That said, I think the 240W Newpowa’s slightly lower 26.71 Voc makes it only a little bit safer and you still should be able to get close: 23.16Vmp * 8A = 185W. Still, keep a close eye during winter.

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Thanks @bxm6306.

I’m planning on running about 50’ 10 AWG MC4 extension cable between the panel and the EB70S. I’m guessing there will be some voltage loss with this long of a cable. Perhaps this voltage loss would offset any concerns about running this panel in cooler weather. Any ideas on the amount of voltage loss with MC4 extension cables?

I’m running 70 feet of 10AWG MC4 cable with no measurable voltage loss pumping 33V @ 8.7A. I carried my EB150 to my apartment roof to measure this first-hand. You shouldn’t see any noticeable voltage loss at that distance with 10 AWG.

That is good information. Thank you.

I also found these sites that calculate solar panel voltage based on the panels specifications and the temperature. I set each calculator to indicate a single panel. According to these calculators I’m only around 28v at 25 degrees with the 250w panel.

So I’m thinking I will be OK with the 250w panel as it doesn’t often get below 25 degrees around here.

https://footprinthero.com/solar-panel-voltage-calculator