ᐅ Quote for photovoltaic system including battery storage – storage yes/no?
Created on: 8 Sep 2024 16:53
H
haus_bau2025
Hello everyone,
My wife and I are currently planning to build our single-family home of about 140 m2 (1,507 sq ft) and are considering whether to build it to KfW 40 standard or not (mainly for cost reasons). We have received an offer from our construction company for a photovoltaic system with 6 kWp and a high-voltage battery from Varta with 6.5 kWh (6.5 kWh) storage capacity, costing around 18,000 euros. Since the battery alone costs nearly 6,000 euros, and I recall reading here in the forum that many people reject a battery because a) it is too expensive and b) it would be better to invest in additional photovoltaic modules instead, I wanted to ask how you would approach this situation. The plan also includes installing an air-to-water heat pump with central, decentralized, or controlled mechanical ventilation (we are still considering these options as well).
1.) Would you remove the battery and replace it with more photovoltaic modules? If yes, how much kWp capacity would you recommend for a single-family home built to KfW 40/55 standard with "normal use," i.e., occasional home office?
2.) Or would you keep the battery and increase the photovoltaic system capacity with additional modules?
Do you have any other ideas or suggestions regarding what we should pay attention to in connection with the photovoltaic system?
My wife and I are currently planning to build our single-family home of about 140 m2 (1,507 sq ft) and are considering whether to build it to KfW 40 standard or not (mainly for cost reasons). We have received an offer from our construction company for a photovoltaic system with 6 kWp and a high-voltage battery from Varta with 6.5 kWh (6.5 kWh) storage capacity, costing around 18,000 euros. Since the battery alone costs nearly 6,000 euros, and I recall reading here in the forum that many people reject a battery because a) it is too expensive and b) it would be better to invest in additional photovoltaic modules instead, I wanted to ask how you would approach this situation. The plan also includes installing an air-to-water heat pump with central, decentralized, or controlled mechanical ventilation (we are still considering these options as well).
1.) Would you remove the battery and replace it with more photovoltaic modules? If yes, how much kWp capacity would you recommend for a single-family home built to KfW 40/55 standard with "normal use," i.e., occasional home office?
2.) Or would you keep the battery and increase the photovoltaic system capacity with additional modules?
Do you have any other ideas or suggestions regarding what we should pay attention to in connection with the photovoltaic system?
In many cases, from a purely economic standpoint, a battery storage system is not yet worthwhile... to recoup the thousands of euros invested! However, this could change soon. Battery storage is becoming increasingly affordable. Once refurbished car batteries enter the market, seasonal storage for homes will become available. Then, you can fill up 70 kWp in the summer and enjoy the benefits through autumn, possibly even into winter. Since many systems will be compensated only through dynamic feed-in tariffs starting next year, having storage capacity during midday will become significantly more attractive.
It is essential in every case to consider the individual situation. Only then can you assess whether a battery storage system makes sense and, if so, what size is appropriate. And if buying a storage system simply makes you feel better, then go ahead and get one.
It is essential in every case to consider the individual situation. Only then can you assess whether a battery storage system makes sense and, if so, what size is appropriate. And if buying a storage system simply makes you feel better, then go ahead and get one.
Hi,
You would still probably drain a car battery storage with a heat pump after a few days during autumn/winter and likely wouldn’t be able to fully recharge it afterward.
Complete energy self-sufficiency is practically not achievable, at least not with a reasonable effort.
By the way, car batteries—if they are used at all—will mostly be applied in industrial or large-scale settings rather than in private households. They mostly rely on lithium-ion cells that require active temperature management for safe operation. You wouldn’t want to just place such a system in your basement.
Typical home energy storage systems are lithium iron phosphate (LiFePO4) batteries, which are much safer but cannot deliver the high currents typical for electric vehicles.
As I have mentioned before: the main advantage of a storage system is that you can run your washing machine in the evening without being annoyed about having to pay expensive grid electricity and wasting your photovoltaic energy for 8 cents during the day. In other words, you don’t have to change your habits and avoid many family arguments.
Economically, a storage system only makes sense if you pay no more than 300–350 €/kWh (about 320–375 USD/kWh). You usually only achieve this if you buy and install it yourself. Most solar installers charge about twice that.
Best regards,
Andreas
Evolith schrieb:
As soon as refurbished car batteries flood the market, there will be seasonal storage for the home. Then you can fully charge 70 kWp in the summer and enjoy the energy into autumn, maybe even winter.
You would still probably drain a car battery storage with a heat pump after a few days during autumn/winter and likely wouldn’t be able to fully recharge it afterward.
Complete energy self-sufficiency is practically not achievable, at least not with a reasonable effort.
By the way, car batteries—if they are used at all—will mostly be applied in industrial or large-scale settings rather than in private households. They mostly rely on lithium-ion cells that require active temperature management for safe operation. You wouldn’t want to just place such a system in your basement.
Typical home energy storage systems are lithium iron phosphate (LiFePO4) batteries, which are much safer but cannot deliver the high currents typical for electric vehicles.
As I have mentioned before: the main advantage of a storage system is that you can run your washing machine in the evening without being annoyed about having to pay expensive grid electricity and wasting your photovoltaic energy for 8 cents during the day. In other words, you don’t have to change your habits and avoid many family arguments.
Economically, a storage system only makes sense if you pay no more than 300–350 €/kWh (about 320–375 USD/kWh). You usually only achieve this if you buy and install it yourself. Most solar installers charge about twice that.
Best regards,
Andreas
andimann schrieb:
By the way, car battery storage systems are, if used at all, more common in industrial or large-scale settings rather than private homes. They are usually based on lithium-ion batteries, which require active temperature management for safe operation. You definitely don’t want to just put one of those in your basement.In fact, there are already some projects aimed at private households as well. It started with small initiatives by individuals, and now a few companies have taken up the idea. You wouldn’t typically install such a battery in your basement, but rather on the exterior wall of the house or similar to how external heat pumps are positioned outside. The primary focus is currently on multi-family dwellings. However, this will change as battery availability increases. One should not expect these solutions to be fully ready within 2-3 years.
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