pep.fermi Posts: 369
edited May 17 in The cake stop

Positing this only for fun.

Installed Nov 2019, ca 9.5kWp, 29 modules (15 East + 14 West), 40deg vertical angle, Hamburg Germany. Cost at the time ca 13keur (less when accounting the 19% VAT I recovered). Feed-in-tarif ca 10ct/kWh

The inverter logs data every 5min. Unfortunately I messed with the computer, so I have fine data only the last months, before that only daily data.

Playing with data is huge fun.

I did consider getting a domestic battery. Long story short: 1) financially it would pay off (after 20yr of uninterrupted functioning) if the price was ONE TENTH of the 10keur 10kWh I got, and 2) enviromentally I see harm for no benefit

Anyone interested just ask


  • Mad_Malx
    Mad_Malx Posts: 5,047

    Sorry to be dim - is this correct?

    financially it would pay off (after 20yr of uninterrupted functioning) if the price was ONE TENTH of the 10keur 10kWh I got

  • photonic69
    photonic69 Posts: 2,584

    Looking at your data is this something you would do again based purely on the financial aspect?

    Sometimes. Maybe. Possibly.

  • pep.fermi
    pep.fermi Posts: 369
    edited May 18

    Yes, it's correct.

    Edit: I got quotation for battery, but never bought one.

    The assumptions in my maths:

    *) same electricity behaviour by my household, don't really see how)why this should change

    *) 3% electricity inflation

    *) battery to last 20yr as the vendor says, not 10yr as the manufacturer warrants

  • pep.fermi
    pep.fermi Posts: 369

    Good question.

    The pure financial aspect: at the end of their 20yr lifetime I should have recovered the initial cost, PLUS an amount equivalent to 2% / yr.

    If you stay 20yr in the stock market you get much better return. Therefore no, purely financially I would not do it.

  • focuszing723
    focuszing723 Posts: 7,237

    Hang on though, your data is for the $h1t months Nov-Apr, daylight hours and winter weather. Wait till the summer when you're pumping those electrons back into the grid at a profit.

    I remember as a kid going on holiday to the Mediterranean seeing solar heating panels on roofs decades ago.

    It is incredible no moving parts and all that energy goodness, lush!

  • pep.fermi
    pep.fermi Posts: 369

    Well spot.

    I have data on a daily basis since the Nov 2019 installation. Based on this data, I concluded by the end of their lifetime I will have recovered initial cost, plus 2% pa.

    Unfortunately the data on 5min intervals I have them only since Nov 2023, because of IT issue. These are the data on the figures I showed.