Photovoltaics are coming up - Options: 19 kWp, 25 kWp, 30 kWp, Storage?

With 10kWh you don’t get far and then the battery is empty and the household power is drawn from the grid... In the end, a lot of organizational effort to optimize for perhaps 3 or 4 cheap kWh. If it’s enough, better to use it during the day on weekends.

Charging during the day is usually not a problem, so the storage for the car would be rather unimportant. Washing/drying can mostly also happen during the day and the dishwasher is then simply started in the morning instead of the evening. However, the majority of other consumption occurs in the evening: cooking, watching TV, lighting, showering/bathing, etc.

Cooking, television, lighting,

That is very little overall. Besides, much of it falls into the sunlit hours in the summer half-year.

Showering/bathing etc.

Here you only have to tell the heat pump not to produce hot water after sunset. Then it doesn’t matter if you bathe at night.

Final note on the storage: The economics for the operator are not the only negative point. Storage is also bad for the environment. Its production requires energy. And even afterwards, it is nothing more than a consumer. In some systems, not a small one (several hundred kWh per year). The stored electricity (including losses) could have been wonderfully used by the neighbor who does not have photovoltaic on the roof.
Current storage systems are also not beneficial to the grid – they only cause more fossil energy generation in the morning when a lot of electricity is needed but little sun is available. At midday, when there is often too much photovoltaic energy, they are already full, so the inverter runs into curtailment at 70%. And at night, when the grid demand is low and, due to sluggish old power plants, there is "too much" electricity, they lower the demand further. All in all, nonsense.

Still, I can understand if someone wants one. I want one too... But you should be informed before buying. If you don’t believe me, you can read the whole thing on the German Environment Agency’s website. Last year, they published a nice paper on photovoltaic systems in the private sector. Everything is stated there again. (Roofs full, no storage). And if even they have already figured it out... ;-)

I can only tell a little bit from my personal experience. My car (company car, I don’t have another one) has only a small battery (35.5KWh). I consciously chose it that way because I drive short distances 98% of the time and, yes, there are other vehicles to choose from if it gets to be longer distances. That was previously a Touran (diesel). It has now been replaced by a Model Y. With a larger car battery, I would have more options when charging, for example, I could fully charge the Tesla’s 77KWh battery on weekends (at home with my own photovoltaic system, charging the company for the used kWh) and would probably get through the week with it. Unfortunately, that is not possible with my vehicle. I just didn’t consider it that way :-( So in 2.5 years, “mine” will be replaced with one with a bigger battery. Also, the Tesla is significantly more efficient in battery utilization (it uses on average about 2 KWh less per 100 km than the Mazda). Using the house battery to charge the vehicle, as mentioned above, makes no sense at all. A 10KWh house battery, if it can deliver 3-phase power, would be drained in 1 hour. But it is supposed to bridge the nighttime power demand. Your house will certainly need about 0.5 KWh per hour given the above annual consumption. For the time when nothing is generated, an approximately 10KWh battery probably fits quite well. Even though the arguments from are for the most part correct mEA, high values for self-sufficiency and self-consumption “somehow feel right.” Also, there are studies on the economics of batteries that differ from the above. Sellers always want to sell one anyway since a few extra “K” are in there ;) without requiring massive extra effort. Overall, though, everyone has to make their own calculation since the conditions vary extremely from one another.

just as an example of how good it feels to use almost all the electricity yourself ;)



Right now, for about 15 minutes, not enough is coming from the roof and my small 3.8kWh battery is being discharged. But it won't last until around 8:00 tomorrow. So it's too small :rolleyes:

Question about storage. If I skip the still too expensive storage for now but treat myself to a hybrid inverter, can I simply install a storage that might then be more cost-effective in a few years without any problems, or do I also need the certified electrician for that who doesn’t want to deal with such stuff??