SMA Solar PV Inverters - monitoring over bluetooth

stuart · 31 July 2017 19:13

@MikeC just got home and checked my emonPI - its doing the same thing as yours.

The code errors out when calling “SMASolar_library.getInverterDetails” it looks like the reply is now incorrect/bad.

As both of our devices have stopped, what I suspect is that there is some value related to the date in the data from the inverter which my code can’t handle properly.

If I comment out the “SMASolar_library.getInverterDetails” call - it all works as normal.

Lets see if it starts working at midnight !

MikeC · 31 July 2017 19:33

@stuart Thank for that. My feed stopped at around 07:40am NZ time which is GMT+12. Just checked over 24 hours on from then and its not back unfortunately. What I wonder tho is if there was some other update that pushed.
Others have said above it might be the BT device but some of the logs seem to indicate there is data coming in from the inverter? Do you agree?
Thanks for everyones help and time!
Regards, MikeC

MikeC · 31 July 2017 19:46

@stuart and I just did a restart of the pi and its back online. Must have been the date format for the 31st? Cheers.

stuart · 1 August 2017 07:55

Very strange - can you file a bug for me on GITHUB for this ?

It must be a problem with the decoding of the packet of data received from the inverter, I’m obviously not decoding this correctly.

MikeC · 1 August 2017 09:55

Thanks Stuart, Done Errors ? due to date · Issue #37 · openenergymonitor/emonhub · GitHub

Cheers,

MikeC

MikeC · 10 August 2017 07:38

Anyone know how to get the voltage and current readings from String1 of the inverter? My emonhub shows String1Volts and String1Amps which refers to string 2 of the inverter. Maybe this is a numbering issue IE string 0 and 1 not string 1 and 2? My inverter is a SMA SB3000TL-21.

Cheers, MikeC

peter5111 · 10 August 2017 08:56

I’m trying to get get a USB Bluetooth dongle working on a Pi3. When I run hcitool scan, I get no devices ( I can see / access my inverters using other tools)

I’m new to linux so please be patient and verbose

Regards,
Pete

stuart · 10 August 2017 09:26

The PI3 has bluetooth built in - are you using that or the “dongle” - perhaps they conflict with one another ?

stuart · 10 August 2017 09:33

You mention that the existing “DCCurrent1” and "“DCVoltage1” are for string 2.

The code that does this is here…

github.com

openenergymonitor/emonhub/blob/emon-pi/src/smalibrary/SMASolar_library.py

# GNU GENERAL PUBLIC LICENSE -  Version 2, June 1991
# See LICENCE and README file for details

from collections import namedtuple
import time
from __builtin__ import long
from SMABluetoothPacket import SMABluetoothPacket
from SMANET2PlusPacket import SMANET2PlusPacket
from datetime import datetime

__author__ = 'Stuart Pittaway'

# Background Reading
# https://groups.google.com/forum/#!topic/sma-bluetooth/UP4Tp8Ob3OA
# https://github.com/Rincewind76/SMAInverter/blob/master/76_SMAInverter.pm
# https://sbfspot.codeplex.com/ (credit back to myself!!)

def Read_Level1_Packet_From_BT_Stream(btSocket,mylocalBTAddress):
    while True:
        #print "Waiting for SMA level 1 packet from Bluetooth stream"

This file has been truncated. show original

Line 420 onwards is commented out at the moment - try uncommenting that on your version and see if the DC values are spit out correctly?

MikeC · 11 August 2017 08:00

Thanks Stuart, Any way to get the readings from both strings? My file is slightly different so I may need to update. Cheers, MikeC

stuart · 11 August 2017 08:32

Your code should be the same as above as this is pulled from github.

I may be able to swap the cables on my inverter to string 2 to test.

peter5111 · 11 August 2017 10:38

bluetoothctl finds my USB bluetooth device but when I try to make any changes I get timeouts and errors. When I scan, I get nothing despite having several BT devices visible.

I’m open to suggestions on how to go about tracking down the actual problem.

Is anybody running the SMA tool on a Pi3 ?

stuart · 11 August 2017 12:13

Are you using a bare-bones Pi3 or running the emonPI/emonhub software on it from the SD card image?

If you are using the SD card image it will disable the on-board bluetooth (you need this disabled).

However, HCITOOL SCAN should find local bluetooth devices without a problem.

peter5111 · 11 August 2017 23:13

Running an emonBase with the supplied SD card, purchased in the last 6 weeks. Pretty sure it is a Pi3.

Until this morning, HCITOOL DEV showed a bluetooth device. Now it reports nothing at all. When it did show a device, running SCAN returned no results.

LSUSB shows the USB Bluetooth module
BLUETOOTHCTL LIST shows one controller, called emonpi, that I responds
“Failed to set power on: org.bluez.Error.Failed”
when I attempt to power it on.

I’m not sure what I have done to upset HCITOOL while poking around last night.

whitecitadel · 16 August 2017 10:48

I also have this running now, its interesting to compare the inverters values to the CT clamp ones, I am measuring under on the clamp. Is there an emonhub parameter that can be adjusted so I can get emonpi to match the SMA numbers (which I assume are the more accurate, I will have to compare lifetime generation with the DNO meter count)

stuart · 16 August 2017 11:19

My SMA inverter under counts the KWH - according to the Elster meter - it drifts out by about 10Kwh a month.

Robert.Wall · 16 August 2017 15:20

Yes. Look at the entry for the node (5 if it’s the emonPi) and you’ll find a line starting
scales = ....
The numbers match in sequence the variable names two lines above 1:1, they are multipliers, so change the relevant one(s) by a small percentage as necessary.

whitecitadel · 31 August 2017 09:35

Thanks @Robert.Wall, using a value of 1.1 for the multiplier on Power2 (solar clamp) of the emonpi has got me within ~10w of the solar generation reading between the clamp and the inverter.

Currently I am putting out ~4600w so I will need to check again late afternoon when production ramps down to see if the value is correct still at lower generation levels.

I am now wondering if I should apply the same correction anywhere else… currently my water is hot so I am not matching immersion to export, that uses a clamp separate to the OEM setup and would be a good check measurement. Due to the way my incoming feed is split to garage and CU my current total consumption is a sum not a measurement at the meter tail.

If there was a cheaper emontx available I would add some more monitoring points

Robert.Wall · 31 August 2017 12:22

Not necessarily. The error comes from a combination of sources, only two of which (the supply voltage, also the reference for the measurements, used twice as it happens - once for voltage and once for current, and the line voltage measurement) are common to all 4 power inputs. So if those are the only source of the error, then 1.1 across the board would be right. But they probably aren’t all of the error, so it’s a case of correcting each input separately. (There’s an article in ‘Learn’ about the errors that are possible.)

whitecitadel · 31 August 2017 13:50

Many thanks, I still have my voltage discrepancy on the emonpi, where it suddenly started to read 10v under at 220v when the emontx reads 230v (old thread on this: Change to Voltage Measurements?) but from the start I was never seeing power output over 4500W which did not seem right as the inverter is rated to 5kW and there is 5.7kWp of panels so I should be over 4500W at peak mid-day output.

Looking on multigraph the clamp and the inverter are tracking very closely now, I will see how it goes once production drops to lower numbers and if the inverter kWh/day gets closer to OEM kWh. If I remember I will have to see what the FIT meter compares in a day to the numbers as well.