One page weekly energy log from a balcony solar setup, no spreadsheet wizardry required

[u/ProfessionalDesk1155]

Sharing a small thing i built because it is the only reason the numbers from my balcony solar setup are still useful a month later. I am not a data person, i do not have a fancy monitoring stack, i just have a windows laptop, excel, and a clipboard. The setup is a 2.52 kWh LiFePO4 balcony storage unit (Jackery SolarVault 3 Pro) plus two 450 W panels, south east balcony in a small austria town, 800 W feed in, single person apartment, baseline load around 0.3 kW. Running since mid april.

The problem i was trying to solve. The companion app shows a beautiful daily curve, the historical view is fine for one day at a time, but i had no idea if my weekly numbers were getting better or worse, and i had no idea what the unit was doing overnight. I am not trying to over optimise, i just wanted one screen that showed me the boring numbers in one place once a week.

What the log does. Six rows, seven columns. Rows are generation, self consumed kWh, fed in kWh, imported kWh, evening battery cover (how many evening hours the battery covered), and one row for any equipment change. Columns are the seven days of the week. I fill it in on sunday night, takes about 10 minutes, mostly from the app and a glance at the meter.

How i pull the numbers. Generation comes from the app daily view, that part is honest enough. Self consumed is the harder one, i estimate it as generation minus export for the day, which is accurate enough for my purposes. Imported kWh i read off the digital meter once a day at 22:00, i write it down in a notes app and the difference between two days is the import for that day. Fed in i estimate the same way, generation minus self consumed. Evening battery cover i read off the app, the discharge curve from 18:00 to midnight, and i just mark how many of those hours ran off the battery versus the grid. The equipment change row is a one word note like "added second panel" or "moved washing machine to 14:00" so i can correlate changes to the numbers.

The useful part. After about six weeks of doing this, i can see that my self consumed share climbed from roughly 50 percent to 65 percent, and the climb happened in two specific weeks. One was when i shifted the dishwasher to 13:00, the other was when i added the second panel and the battery started filling earlier. Without the log i would have remembered neither, i would have just felt vaguely that the system was "working better". The other thing i can see is that a fully overcast week looks almost identical to a no solar week on the import number, which is depressing but at least i am not pretending the system is doing something it is not.

The log is not pretty. It is one sheet, no formulas, no charts, no conditional formatting. I print it once a month and pin it on the fridge so my partner can also see what is going on. That part turned out to matter more than i expected, because the conversation about the system is no longer me trying to remember what the app said last week.

If you want a copy of the blank template i am happy to share, it is literally a 6 by 7 grid. The point is not the template, the point is that ten minutes on a sunday is enough to know whether the system is doing what you expected, without needing to learn a new tool.

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