Live loader - validation of data?

Questions
#1

G’day,

I’ve been exploring using the Live Loader as a possible solution to an earlier problem I had posted about (is there a way to add Live data back into pvoutput).

I’ve run into an issue with validation. The data looks OK but I think I may have run into a specific issue I’m not sure how to resolve. When running validation it often gives up and marks a bunch of records to skip and/or in red. I think I’ve worked out that it does this because the help page advises that the energy generated MUST only be a larger number (i.e not a series of energy values at the point in time).

I wanted to check if this was in fact the expected behaviour.

Enphase’s data export gives me values in the form

time (in a 15 minute increment) , energy generated during that increment (in wH)

07:00:00,10
07:15:00,20
07:30:00,30
07:45:00,20

The last record would get skipped…

I’ve searched google and found an old thread that describes this specific issue but I wasn’t able to work out if this had been resolved or not.

Namely that Enphase’s CSV specifically says it exports in the form of time and energy (in Wh) but the thread seemed to indicate that pvoutput expects to see a cumulative energy in wH (even if the cumulative button is not ticked).

Any ideas if this is a bug in the live loader or simply needs some massaging of the data from Enphase reporting…

#2

Check that the correct Energy position (2) and format (Wh) has been selected in the previous configuration screen.

#3

Yep, I have checked these and the positions are correct.

I’ve tested a number of things and come to the conclusion that either it’s a live loader bug… or live loader is behaving properly and the documentation needs to be updated (I’m willing to submit updated doco if I know where to send it…)

In summary, you will get Enphase data that looks like:

date time timezone wH-generated

You can import this CSV into excel and then create a new column with a sum formula that will create a cumulative update. You can safely ignore all the 0 data points and just work on the start and end fields where you generate data (power) and of course all of the ones in between.

I then cut and paste this into a text file and manually process it to create entries that look like:

07:00,0,0
07:15,10,10
07:30,10,20
07:45,5,25

As you can see the third field is cumulatively adding up.

You then import this using live loader, telling it that position 1 is the time and position 3 is power (not energy…)

This is where I had problems with the documentation because there seems to be confusion between energy and power (kWh and kW) which appears to be mixed up in terms of what it is asking for and what it actually needs.

I’ve now added back in the ~5 days of live data I didn’t originally have and it mostly seems to come up ok (with one exception I’m working my way through… how do you erase a days data and start that day completely from scratch…)

#4

The problem is Enphase is providing the energy produced since the last interval i.e. 15-minutes

The Live Loader is expecting the cumulative value since the start of the day, i.e. the energy value cannot decrease.

#5

This was something that wasn’t initially clear to me either, but it eventually clicked after reading the API docs a few times - if you check the “Cumulative” option it means the data is lifetime cumulative, otherwise it’s cumulative for the day - but it’s always cumulative, the only thing you’re changing is the reference point.

That makes sense, because it means the intervals can be uneven and you’ll still have accurate data, otherwise you’d either need to specify a time span or make the assumption that it’s the amount since the last status, but that might not always be true (if an update was missed for whatever reason).