I'm not OP, but I would look at this tool I found a while back. Ridiculously useful and underrated. I think someone on HN linked it, as I've not found a tool so

I'm not OP, but I would look at this tool I found a while back. Ridiculously useful and underrated. I think someone on HN linked it, as I've not found a tool so useful via googling despite many attempts. https://re.jrc.ec.europa.eu/pvg_tools/en/ https://re.jrc.ec.europa.eu/pvg_tools/en/ What you're looking for is the "Off Grid" tab, plug in your details. e.g. solar array size, size of battery, etc. Then click visualize results. After visualizing, there are a few tabs to help you make some decisions. For your case (Netherlands, it looks like a 5.4kWp solar array and 4kWh (I assumed 5) used per day, and with a single 5kWh battery, you should be able to go off-grid :) In fact, during summery months, you could even push to the grid. This tool even looks at cloud data based on various databases. I don't know of it's accuracy, but I'm inclined to trust it.