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SolarNoob

Pylontech US2000B Plus

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On 2018/05/10 at 1:22 PM, Mark said:

@SolarNoob

Do you upload to PVOutput?  It would be really nice to see your output and efficiency especially with the Pylontechs charging in the morning!

Thanks

Mark

Yes I do, let me know your thoughts?

 

 

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Hi again @SolarNoob

Looks like the PylonTech's are treating you well.  Are you off grid and if not how much do you use of the Grid to top up and when.

I would love to go the PylonTech route but have more load than I think 4x PT's will handle... but then I compare myself on PVO I see you seem to handle fine ;)

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PS: My performance is low as I don't use my batteries at all... just float them off PV during the day... I have what @Chris Hobson and others call a "draadkar or el cheapo" set of 12V 100ah Excis ... :o

Regards

Mark

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@Mark  I am not completely off grid. I run off batteries from 8 PM to 6 AM the next morning when my geyser switches on (also wired through the inverter), the geyser run off eskom in the mornings. Once the solar production is high enough it covers my base load and the rest charges the PT's. My geyser runs again at roughly mid day to heat water for the evening, this time the geyser runs off of PV. As PV production tapers off, I gradually use more eskom until the batteries take over again at 8 PM.

The PT's happily take 25A (they can take more), the highest the infini can charge at until fully charged when the PV supply will suddenly drop off sharply to cover the base loads. Running those ten hours from batteries consumes roughly 45% of the total capacity of the PT's so depending on demand my batteries are usually charged before the geyser runs again at mid day. Unfortunately my loads arent high enough the entire day to consume the full PV supply and that effects my efficiency. 

I also only charge the batteries from solar. Running my system this way I have reduced my eskom bill by 70 to 80% and when the grid goes down, which it does quite often, the PT's can carry me through the night if need be. I prefer to keep the battery consumption to roughly 45% because I need the extra backup capacity for backup for my reef tank.

I cant praise the PT's enough, they are plug and forget with the BMS taking all the worry out of the equation. They work flawlessly and they absorb charge like a sponge. I had 8 Trojan T105-RE's before the PT and some days they wouldnt be fully charged. This seldom happens with the PT's due to their charge efficiency.

Are you off grid?

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1 hour ago, SolarNoob said:

@Mark  I am not completely off grid. I run off batteries from 8 PM to 6 AM the next morning when my geyser switches on (also wired through the inverter), the geyser run off eskom in the mornings. Once the solar production is high enough it covers my base load and the rest charges the PT's. My geyser runs again at roughly mid day to heat water for the evening, this time the geyser runs off of PV. As PV production tapers off, I gradually use more eskom until the batteries take over again at 8 PM.

Are you off grid?

When I have the money this is the way I'll go... Chris and I speak regularly but sadly we see each other seldom... He is also keen on the PT's and I like your setup.  I do almost the same with the Infini 3+ but just don't have the batteries yet.

Thanks for the feedback!

Cheers

Mark

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5 hours ago, SolarNoob said:

cant praise the PT's enough

My only frustration with them is the very narrow voltage window. They absorb at 53.2V and raise an alarm at 54V. That gives you a mere 0.8V to work with. Now you might think that with the legendary blue equipment we don't have voltage overshoots, but that's just half the picture. I learned in the mean time that there is a technique used by some MPPTs where they essentially switch from a buck converter to a PWM charger (fire only one of the switches in the buck converter) at low power levels, because it is more efficient, and in this mode the voltage regulation is not as good as in the higher power mode. Also, many canbus BMSes are quite slow, only providing a voltage reading or charge level every two seconds or so, with propagation delays and all that... it is perfectly possible to go a little over for a second or so. Add to that two more factors, that a very full lithium is VERY prone to sharp voltage increases AND that customers make use of the C/2 capabilities of these batteries and use way smaller batteries than they would with lead acid... and you can quickly see where it's going.

In short, I would still advise that you don't use a single rack. At least use two racks so you have a bit of spongy current acceptance at the top end.

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My pt system is set to max volts of 52v with a charge of 48 amps.

The infinisolar float charges them at 1 amp.

Because they are bms I have connected them to the infinisolar in sets of 2.

This has (inadvertently) reduced the amps per cable to 24 amps as the current is split up between the two sets of 2 each.

Their very quick charge time is always an eye opener

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9 hours ago, plonkster said:

In short, I would still advise that you don't use a single rack. At least use two racks so you have a bit of spongy current acceptance at the top end.

I agree with this statement.

I started with only two Pylontechs for about a month and then added another two. The two PT's on their own were getting over voltage errors in the logs. I havent had these errors again since running four batteries.

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2 minutes ago, SolarNoob said:

The two PT's on their own were getting over voltage errors in the logs

I really think more needs to be done to educate people about that. The Lithium sellers are all like "oh, you only need a third of the capacity compared to lead acid", and then you have people who install a 7kw PV array, 5KVA inverter and a 2.5kwh LFP battery (the exact reverse of what you'd do in lead acid territory). "Because I want to use that power during the day and have some left to charge the battery". And then they also want to keep the battery completely full most of the time, and sometimes feed the excess into the grid too. And then on top of that there are sometimes feed-in limits imposed as well (eg no more than 3.6kw on many single phase installations). It's almost as if people lost all common sense now that the batteries are better :-)

1 hour ago, Johandup said:

My pt system is set to max volts of 52v with a charge of 48 amps.

Isn't 52V a tad low? I believe they want to float at 53V? On the other hand, I did note that the Pylons have a somewhat high float and absorb voltage. For example, a BYD wants to float at 55V and it has 16 cells, so that's around 3.45V per cell. Transferring that over to Pylon territory should mean 52V, but I'm sure the spec sheet calls for 53.

52V is probably fine though.

3 hours ago, SilverNodashi said:

What's your thoughts  on BYD?

Good batteries. First, they are 16s vs the 15s of the Pylontech, so for comparative purposes one must always take that into account as well. They have a wider voltage range to work with (possibly because of the relatively lower float voltage and the extra cell), which makes life a tad easier at the top end. But I think the Pylontech has the better BMS, from a functionality point of view.

The BYD publishes a static charge voltage of 56.5V. But you can get nowhere near it, because the BMS sends the stop charge signal at 55V and only reactivates charte at 54V. It's like a hard limit, it produces this beautiful sawtooth figure that nobody likes to see. So you essentially have to ignore the charge voltage info from the BYD BMS. The Pylontech, as far as I've seen (I haven't seen that many) has dynamic voltage control, in other words, if there is a high cell, it can lower the charge voltage to compensate for it.

Proper dynamic voltage control works much better than attempting to regulate the charge current, or that has been my experience at least.

So my opinion, the BYD is possibly a slightly better battery, but the Pylon has the better BMS. That is, let me stress again, an opinion only.

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Chatted to Manie this evening ICC communicates with Pylontechs. Says probably 100 Pylontech installs a month based on the number of communication cables they sell. 

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