How to troubleshoot: PV1 PV2 over voltages on AC300 My TIPS

To start with, my configuration for a better understanding: AC300 + (3xB300) + 2400 Watts PVs ( 1200 watts PV1 +1200Watts PV2).
Sometimes you get an alarm with the message "Overvoltage PV1 or PV2 or PV1 and PV2.(I think the problem is linked to the deviant regulation: voltage and current of the photovoltaic panel boxes.)
In fact, the PVs don’t react correctly or quickly enough when the sky is grey and then becomes extremely bright.
The problem is that the AC300 can stay out of the sun for as long as the message remains.
To save time, here’s my solution: :blush:

My solar panels are easy to access, so I’m just going to carpet one of the panels on each path (PV1 and PV2). Then, on the AC300 side, I unscrew the PV1/PV2 connector.

The error message disappears, so I screw the PV/PV2 connector back on.
At that point, I keep an eye on the PV output display and wait for around 300 watts.
At that point, I remove the mats from the PV panels.

That’s it, now PV1 and PV1 are operational. :grinning:
In the Normandy region of France, I have this rare experience from time to time.
Here’s how I can help.

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What is the configuration of those 1200W of panels? How many panels do you have and what’s are their Voc and Vmp?

Hi Snowstorm,

i used 305 W monocristallin Victor energy.
PV1= 305W + 305W + 305W + 305W (in serial) = 1220W (just limit :grin:)
PV2= 305W + 305W + 305 + 305W (in serial) = 1220W
According to my tests, this problem can occur when the sky is overcast and the sun suddenly shines strongly.
4 x Voltage open = 158.8 volts, and normally the max input voltage AC300 is : 150VDC.
I maximise the PVs.
Solution2: I hide a small part of a panel from the sun.
In Normandy (France), the sun is not extraordinary. :cry:

Have a nice day,

Your combined nominal Voc is 160V, as you also mention.
Already way too much for the AC300 and it will only get worse in winter.
For your setup you are going to have to use the D300S voltage reducer. It will regulate and drop the voltage down to around 125V, ideal for the AC300.
I own three of these units (my roof-top arrays also have a Voc of around 160V per MPPT) and they work great.
The only slight “issue” is that they emit a high-pitched noise above 600/700/800W but it is tolerable, especially if the unit is on a different floor or in a storage room. And they won’t emit any noise at night, obviously :).

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Can you give me more informations on the D300S, I don’t know it at all, who is the manufacturer and where can I buy it please?
and if possible to limit at 145 volts ?

Thank you for your help. :blush:

It is manufactured and sold by Bluetti and can be found on their website under “Accessories”.
Definitely in the US and Japan but I’d think (hope) they also sell it in Europe. Check on the Bluetti EU site. If it is not currently sold there (or if it is out of stock, which it is, sometimes), I’m sure they will help you to obtain one somehow or let you know when it will be available.

Thank you for this information, it is sold in France.
Last question:
Will my panels still produce 2400 Watts in full sun, even with the d300s?

Thanks for your help :grinning:

Yes. There is a very slight loss, but it is practically unnoticeable (it is around 2%, if my memory helps).

Yes, effectively: 97,8 % :blush:
If I later wish to buy the second generation AC500, I think it will also be usable with it as it is the same PV input specification?
In France, in the next few days, there’s going to be ‘Black Friday’, so I’ll be buying it then. :grin:
When do you think ?

Yes - the arrays should not be a problem. I use them with 3 pairs of 1500W arrays already, actually.
As for the AC500 compatibility: although it is not explicitly mentioned in the D300S manual, I think that is only because the AC500 did not exist back then when the D300S came out and the manual has not been updated yet. Otherwise I don’t see why not.
@BLUETTI can probably reconfirm.

Actually, just re-read the D300S manual and it seems the AC500 might be omitted on purpose (and it also includes the EP500/Pro, which are considerably newer).
Best case (if it still can be used with the AC500) it seems it will be limited to 2400W (which you probably won’t mind, unless you want to upgrade the panels as well.
Worse case: there will be an updated version to make it fully compatible with the AC500 (will have to purchase the updated module once again then, unfortunately, but can still use the existing panels).
Worst case: there will be no such solution/support for the AC500 - this I can’t imagine …


Thanks for your help.
I’m struggling to reach 2100 watts with 2440 watts of solar panels.

AC500 specifications PV:

Have a nice day,

You mean now? In early November? In Normandy?
I’m pulling 2.2kW max, while being over-paneled to 3kW and my latitude would be southern Crete if I was in Europe.
I think you are good …

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Why do you need this expensive device? Why don’t you connect the panels in parallel and limit the voltage to 120V?
The current strength limits itself.

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Hi gbk,

Right now in Normandy, France, with 2,400 W of panels, I’m making about 2 kW a day. :grin:

That voltage reducer is likely overkill, you are barely over the limit and that is an expensive device. Instead of buying that, I would suggest you get a few more panels and change to a combo 2p3s configuration.
Note that you can go over the wattage limit, but not the voltage. In fact, it is a common practice to go over the wattage limit so you can still get full power even if it isn’t perfectly sunny. It is known as over paneling.
No you cannot connect them in parallel and expect 1200w per string. While that will reduce the voltage, it will increase the max current to 16-18A. Since the AC300 can only take 12A, 25-33% will be wasted and you will only get around 900W per string. But you will likely get that 900w per string even under imperfect sun.
Something to consider is that instead of doing 4 panels in series (4s) per string, you can add 2 panels and do a 2p3s configuration where each string has 2 strings in parallel where each parallel string have 3 panels in series. In this setup, your Voc is 120v, and you have a max of 1800W per string. You won’t get 1800W due to the current limit. But you will get the full 1200W even when the sun isn’t perfect.

Hi Akel,

Thank you very much for this tip, I hadn’t thought of it.
How can I limit the voltage to 120V or 140V, I’ll need a device too?
In //, the voltage remains the maximum voltage of a panel (Vmpp 32,5 volts), but the current is added in //.
Path N°1= PV1 i1 + PV2 i2 + PV3 i3 + PV4 i4 = 9.38A x 4 = 37.52 A Max
In serial, i limit the current, because the rate input current is: 12A by chain.
I think that in //, the problem sitll there and different ? what can you think ?

AC300 input PV:

Thank you for this very important information.
Many thanks to you.

Yeah, @snowstorm’s is a solid advice, especially if you are just planning your installation, have the necessary real estate for the extra panels and given the year-around cloud situation in Normandy.
Basically, what he is suggesting is a more massive over-paneling and spending the money on extra panels, instead of the D300S. He has a point.
In my case (to answer @Akel’s question) it was an existing roof-top setup that predated my Bluettis and rewiring it would have been non-trivial and would have cost at least as much as the D300Ss (most probably significantly more).
Even if I was doing the planning from scratch, I would not have the roof real estate for 24 panels (for a 4 x 3s2p setup - I have 2 AC300s). My weather is also nicer than yours, as mentioned earlier.
Beside, I’m rich and can afford “wasting” money on multiple D300Ss :smile: (no, I’m not - far from it, unfortunately …)
Overall, I’m happy with the D300S, they work for me as intended (so far, fingers crossed) and really happy Bluetti makes them. Your mileage may vary …

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You do not want to connect 4 panels is parallel, as that would increase the max current to 36A, far beyond what the AC300 can take (12A), it won’t break it, but you will waste most of the power potential.
If you have access to the panels and extra space consider getting 6 panels per string. Wire 3 of them in series to get a 3S setup (120v, 9A). Then wire the 2 sets together in parallel, creating a 2p3s setup (120v, 18A). This would give you a robust setup where you won’t exceed 1200W, but will get 1200W even in imperfect sun.
If you don’t have the space or cannot require, than the D300S is an option to get 160V working.

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hi snowstorm,

The AC300 supports 12A MAX per path.
I have 4 solar panels per path.
Each panel generates a maximum of 9.38 A.
I knew in advance that I could have this phenomenon due to a very, very cloudy passage, with extreme sunshine. :grinning:
Solar panels don’t know how to handle this very rapid transition, so they generate a very short overvoltage.

  • Result:

The serial configuration in my case is the best.
In fact, I’ll have to add the D300S if I don’t want to have from time to time
the message: PV1 over voltage
Or remove one panel to lower the voltage < 150 VDC.

I don’t have six panels per path.