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Hi all, just sharing my recent experience working with a Growatt SPF 3500 ES and the included WiFi-F module. I have a few other solar systems already feeding their data into InfluxDB and Grafana, and wanted the new Growatt unit to do the same. Otti’s project on GitHub provided some inspiration...

As with all alleged battery breakthroughs, I'll have to see it to believe it. So many broken promises over the years has me irreversibly cynical. :LOL:

Not true. Some inverters float the panels at very high voltages with respect to ground. An unlucky person who touched a faulty panel frame or rack could have a nasty surprise/early death. This is why proper earthing of mounting systems is considered mandatory by practically all panel, racking...

Here's the list of working registers: Name Address Offset (from 0x1000) Type Multiplier Unit System Status 0 uint16_t 1 0: Standby; 1; (No Use); 2: Discharge; 3: Fault; 4: Flash; 5: PV charge; 6: AC charge; 7: Combine charge; 8: Combine charge and bypass; 9: PV charge and bypass...

I've taken a bit of a different approach to this issue and addressed most of it in software. I have a JK BMS, and have been using the amazing esphome-jk-bms software by syssi to monitor and send all the BMS statistics to MQTT. With a small modification, I've configured this to switch a relay on...

I completed the testing this morning: Conditions were ideal with a clear blue sky and 24°C temperature. After some experimenting with positions, I ended up using an east-west facing setup as this aligned the panels best with the sun. One panel was fully illuminated while the other was only...

Here you go. The switch in series with the 20R resistor is a momentary swtich for pre-charging the capacitors, the other is your high-current toggle switch. The momentary switch wouldn't need to be high current type, 5A would be sufficient.

For anyone else who ends up here looking for answers, after a lot of searching and bit of trial and error, I've found that the plug type on the JBD BMS (for both the balance wires and the 4-pin UART/NTC connectors) is actually HY2.0. Molex PicoBlade, JST-PA, JST PH 2.0 and the others mentioned...

Just an update on this - I think it's important to discuss our successes as well as failures, and this one was definitely a fail. I bought an old office style water cooler for spare change and stripped the compressor and refrigeration loop out of it. On its own it was able to cool the 2L water...

The information is relevant because competition within this market, especially in China, is brutal. Vendors will do just about anything to increase their margins or produce a product that is cheaper and more attractive than their counterparts. This includes ripping off and cheating their...

They'd be fine, they'll just produce a bit more heat. 0.75v @ 10.2A = 7.65W heat/wasted energy. 0.22v @ 10.2A = 2.24W heat/wasted energy. Worst case it's a 0.4% difference in the total maximum output of your array. Not worth worrying about.

In my setup the ESP queries the BMS for all its running statistics every few seconds, and then uploads the data to InfluxDB. It also operates the balancer relay if the necessary cell voltage conditions are met. While this was coded to work online/while connected to WiFi, it'd be trivial to...

A quick update: I've successfully programmed an ESP8266 to retreive data from my BMS (JBD/Overkill) and translate it into emulated Pylon CAN bus messages. The output looks identical to what the inverter would expect when configured with Option 5 - Li and Option 36 - L52. When I have a moment...

I've always wanted to try this approach. Anyone who monitors their MPPT closely will see that the voltage it determines to be the maximum power point doesn't vary much throughout the day - about 10% even with changing angle of the sun, cloud cover, etc. So the approach of holding a fixed array...

It depends on a few things: - Will it be used outside for extended periods? The extension cord probably isn't manufactured to withstand the rigours of daily exposure to high levels of UV, moisture, heat and cold for years on end, as they're usually intended for short term, temporary use. PV...

You'd place the resistor in parallel with the disconnect switch, with its own momentary switch. That way while the big disconnect switch is in the "off" position, you can hold the momentary switch for a few seconds, completing the circuit through the resistor to pre-charge the inverter's...

No, it's in parallel with the disconnect switch, so it'd do nothing. I'll upload a circuit diagram a bit later to make it a bit more clear.

Just wanted to express my appreciation for those in this thread who put the miles in to diagnose and understand the issue of Growatt inverters ceasing solar production/charging. I was stuck on this same issue until coming across this thread. I made the recommended adjustments and now it's all...

After a bit more fiddling around I managed to resolve this - the latest version of JBDTools (V3.7-20220415) was able to write the settings successfully. This software is somewhat hidden on the Jiabaida website, so here's the link for anyone else experiencing this issue...

It's hard to tell from the photos if you have the necessary space, but you could wrap some damp cloth around the cell terminals to try to avoid heat conduction through them towards the cell, and use a metal or fiber cement heat shied to protect against the hot air stream. Check your insurance...

Extreme indeed, I'm amazed you didn't see a difference in that scenario. A great example of the value of real-world testing.

It seemed unanimous earlier in the thread that blocking diodes are unnecessary and generally a waste of time and energy. We then moved on to series vs parallel connections for panels facing different directions.

I had an unusual problem to solve recently - I have a cabin that's completely off grid and not connected to any public water supply, running on stored tank water only. This is in a fairly arid area, so water is precious and can't be wasted. One risk that's been sitting in the back of my mind is...

While this is true, I've managed to find peace with my Growatt AIO. Yes, the support is awful and the standby power can be high. But the unit does work really well once properly set up. I have mine running some heavy equipment in a workshop and it's never missed a beat. When I don't need AC...

I don't think you'll have any problems, the 390w figure just indicates how much power the Tracer can deliver according to the maximum current it can handle at a given voltage. Its firmware will self regulate and prevent an overcurrent situation. The total maximum PV power for the 3210AN at 12v...

This has been an interesting read and a failure mode I've not considered before. It would be trivial to make an independent device consisting of a voltage divider, micro controller and solenoid/relay to monitor voltage and force a disconnect if battery voltage exceeded a specific set point...

Yes, I dumped the stock firmware before I started experimenting with my own, I've attached it for whoever might want a copy. I can also post all the MODBUS registers if it'd be helpful, through trial and error I found that the documentation for these systems has a couple mistakes and many...

You only need to care about the voltage drop across the diode, which is where the inefficiency and heat comes from. The total voltage of the system doesn't really have any effect on this.

Try adjusting setting 12 (B2AC) to something above 48v. It doesn't have any functional effect in your configuration, but it might then allow changing 21 to your preferred value as the two are related. If you have no grid, you should probably also change 14 (charger source priority) to OSO...

That's correct, however my ESP32 connects to the BMS using Bluetooth. This is preferred as it has complete electrical isolation. The buck converter powering the ESP32 is currently downstream of the BMS power MOSFETs. This means monitoring will stop in the event of the BMS cutting off discharge...

My cells from Luyuan arrived this morning, total time in transit was 53 days. They look to be genuine EVE with the clear "B" marking on the QR labels, which is what I was expecting. It might be a while before I have a chance to test them properly, but I'll post the results of an initial...

Correct. It'd find the maximum power point close to where both strings are contributing as much as they can. It wouldn't be as optimised as an individual MPPT per string, but it wouldn't be far off, either. The MPPT voltage of a string of panels doesn't vary with lighting conditions as much as...

After reading this thread I'd be far less likely to buy any Victron gear. If I was to pay the premium for top quality equipment, I'd expect to be able to open, diagnose and repair it after the warranty expires. It's clear in this case that Victron intended these to be throw-away items, making...

You might think so, but the resistance of the wires and terminal connections at high current make a non-negligible difference across the batteries. When under load, the wiring in first diagram pulls more current from the 4th cell due to lower resistance. This leads to an imbalance in...

I'm with you on this. I can understand why a vendor on razor thin margins might not want to deal with a customer who is upset about a <1% difference in tested capacity verses spec, particularly when that testing occurs using uncalibrated equipment, outside a laboratory environment and with no...

I'm probably a bit late to the party, however I did a somewhat related test last year, and found parallel is a more optimal arrangement for when whole panels are facing towards/away from the sun: https://diysolarforum.com/threads/blocking-diode-question-please.51248/post-653783 This would be...

I made the TechBuilder 1kW MPPT board. It worked well for some tests, but the MPPT algorithm is somewhat simple and can get stuck on a false maximum power point. The author seems to have abandoned the project too, so it's only worth picking it up if you're able to troubleshoot any issues...

Yep, my mistake. All these numbers are meaningless out of context, so let's tabulate them: Setting # Name Range Your configuration 12 Back to utility voltage 22.0V~25.6V 25v 13 Back to battery voltage 24.0V~29.0V 28.5v 19 C.V. charging voltage 24.0V~29.2V 28.8v 20 Floating charging...

Yes, this certainly contributes to the outcome and there are a lot of factors influencing the combined result. As always the real-world outcomes will differ from lab conditions and theory. Assuming some good weather I'll go ahead with the series/parallel shaded tests this weekend. I'm quite...

While I agree with all your points, the DIY market may be bigger than you think. I keep a close eye on eBay and FB Marketplace locally for second hand panels, and all reasonably priced offers sell very quickly. There are even a few solar installers selling the used panels they remove on a...

Yep, it sounds like your stick is stuck in a reboot loop because it can't connect to your Wi-Fi. You definitely don't need the <> characters in secrets.h, they're just placeholders. For example, if your SSID is wireless and your password is password123, the respective lines should look like...

Nice, thanks for the tip @Symbioquine. I've ordered one of these RS485 adaptors and will test with my setup. For my purposes I use a separate ESP8266 and RS485 adaptor for each charge controller. This way I don't have to connect them all together or manage device addresses. The ESP, level...

I bought a couple similar to this a few weeks ago, however didn't end up using them. There's a few variants of these ESP01 relay boards, it's important to use the type that exposes the UART interface (TX, RX, GND) so you can connect it to the BMS. I personally dislike working with the ESP01...

yeah, I've learnt not to trust either my BMS or inverter for SOC calculation. Both aren't accurate enough to properly monitor consumption over long periods of time, particularly at low currents. I just watch for the accelerated voltage drop as the pack discharges or call it a day once the cells...

I've had a chance to expand my test battery and sort out the BMS issues that were slowing progress. Testing is nearly complete with most functions working as expected, most importantly the external relay for the active balancer. The shared UART connection still needs a bit of work, which will...

Wow, that's some crazy cell construction. You could try using a high power hot air gun to melt the solder, though I'd be worried about how much heat would transfer to the cells, both through the hot air stream and conduction through the terminals.

There's a lot of reasons the market has moved away from small panel sizes - mostly driven by cost. As average system sizes (kW) increase rapidly, larger panels mean less frame material, less mounting hardware and less electrical connections. This benefits the consumer with lower installation...

I'm the same - I've done the tests both on the ground and on the roof, and at least for my systems, parallel produced more power by quite a large margin. While it's an interesting thought experiment, there's too many variables at play to isolate a single factor and draw conclusions around the...

I think you'll find that a BMS is always powered from the batteries through their balance cables, so the direction of the battery pack current is not relevant to their operation. Because of this they can be active even during a low voltage disconnect and when a charger isn't attached or...

I agree with @timselectric, the bus voltage looks ok, though the BMS must be interacting poorly with the Growatt. Change setting 05 to USE, choose some conservative voltages for your constant voltage and float settings and then monitor. I use 55.2 for CV and 54.7 float with very consistently...