ᐅ Evaluation of Photovoltaic Proposal and Components

As an example, here is my system (7.2 kWp) with a 10 kW battery storage.

Energy yield on 29.04.2023 8.52 kWh
Consumption 9.73 kWh
Grid feed-in 0.10 kWh

Energy yield on 06.05.2023 19.65 kWh
Consumption 9.22 kWh
Grid feed-in 0.11 kWh

Construction costs were 11,000 euros, or 1,527 euros per kWp, including the battery storage.

As you can see, there is no grid feed-in thanks to the battery. The battery also covers one or two rainy days. I only plan to control the water heater with a timer so it heats between 10 a.m. and 3 p.m.

I’m not sure it makes much sense to fully cover the roof without buying a battery. Even though many people do this, it would not have been an option for me, even though I have several hundred square meters of surface area.

And when there is snow on your system in winter, it doesn’t matter how big or expensive it was. The output will always be close to zero!

Bausparfuchs schrieb:

I’m not sure if it makes much sense to fully cover the roof and not get any storage at all. Even though many do it that way, it wouldn’t have been an option for me, despite having several hundred square meters of space.

It’s clear that you don’t really know.
I’m not fundamentally against storage systems, but you can calculate it. Just because the storage system (possibly) pays off, doesn’t mean that investing the same amount of money spent on storage in additional photovoltaic (PV) modules wouldn’t have been even more profitable.
Personally, I don’t consider profit maximization in this area very important; we are getting a storage system as an ideological choice, and it will at least pay for itself during the warranty period.

Still, all of this can be calculated. I wouldn’t recommend a storage system to anyone if it doesn’t amortize within the warranty period. And when I see offers where a 7 kWh storage costs over 7,000 Euros (over $7,000), that’s a high-risk purchase. The chance that the storage system fails before covering the initial cost is quite significant.

Basically, I agree with Kati, but how can the choice of an attic be ideological in nature?

RotorMotor schrieb:

Basically, I agree with kati1337, but how can the decision for a battery be ideological?

I don’t know if I’m off here, but I like the feeling of using as much electricity as possible from my own roof myself. I actually prefer that over maximizing profit from my investment. If I wanted to maximize profit, I would probably ditch the battery, find space for more panels, feed the surplus back into the grid, and then try to shift our consumption to daylight hours as much as possible.

It just feels better somehow to route power from the roof to my battery and from the battery to my PC, rather than buying green electricity from the grid. The power from my roof feels even more “green” than the one from the hydropower plant. Maybe “ideological” is the wrong word and “crazy idea” fits better. 😉

Yes, OK, it is often more a matter of egoism or simply for fun. Because a storage system does not really help the environment at first.

RotorMotor schrieb:

Because a storage system does not help the environment at first.

Yes and no... Of course, the storage system requires production resources. On the other hand, if a household with a storage system manages to optimize its own electricity consumption to minimize external supply, this helps with current grid capacities and also reduces some kilowatt-hours that would otherwise need to be generated by fast-response gas or coal power plants. Likewise, on sunny and/or windy days, it can prevent some curtailment of externally switchable photovoltaic or wind energy systems.