ᐅ Photovoltaic system with supplementary storage heaters
Created on: 18 Dec 2019 20:10
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bloodyscorpionB
bloodyscorpion18 Dec 2019 20:10Hello dear forum,
we have bought an older solid house.
The house is heated with night storage heaters and a tiled stove.
Is it worth installing a photovoltaic system with a storage battery? The roof faces southwest and has a dormer.
I look forward to your messages.
we have bought an older solid house.
The house is heated with night storage heaters and a tiled stove.
Is it worth installing a photovoltaic system with a storage battery? The roof faces southwest and has a dormer.
I look forward to your messages.
Phew… night storage heaters.
Basically: photovoltaic systems are always worthwhile if you can use a reasonable amount of the electricity yourself. Currently, a battery storage system is usually not economically viable.
With night storage heaters, the calculation might be different, but it depends specifically on the storage system’s lifespan, your self-supplied electricity during off-peak hours, and the size of the photovoltaic system. Additionally, to generate a significant amount of electricity for nighttime use, your photovoltaic system would need to be considerably larger than 10kW. This requires relatively expensive feed-in management, which reduces your profit margin again.
Example: With my 15kW photovoltaic system, I generated just under 8kWh of gross output today, and it was a fairly sunny day. In my KFW 55 house with about 170sqm (1830 sq ft) of living space, I had a heat demand of 18kWh from midnight until about 8:30 pm. This is heating demand only, measured via an uncalibrated heat meter on the heating circuit. The outdoor temperature was about 10°C (50°F) during the day and 2°C (36°F) at night. So even here, it doesn’t pay off.
The only really sensible way to use solar electricity for heating is with a heat pump, which stores heat in a buffer tank during the day when there is enough sunlight, operating with a coefficient of performance of 3 or higher.
Putting aside all theoretical calculations, I have serious concerns that the usage profile of a battery storage system does not align with the load profile of night storage heaters, which would massively shorten the battery’s lifespan.
Basically: photovoltaic systems are always worthwhile if you can use a reasonable amount of the electricity yourself. Currently, a battery storage system is usually not economically viable.
With night storage heaters, the calculation might be different, but it depends specifically on the storage system’s lifespan, your self-supplied electricity during off-peak hours, and the size of the photovoltaic system. Additionally, to generate a significant amount of electricity for nighttime use, your photovoltaic system would need to be considerably larger than 10kW. This requires relatively expensive feed-in management, which reduces your profit margin again.
Example: With my 15kW photovoltaic system, I generated just under 8kWh of gross output today, and it was a fairly sunny day. In my KFW 55 house with about 170sqm (1830 sq ft) of living space, I had a heat demand of 18kWh from midnight until about 8:30 pm. This is heating demand only, measured via an uncalibrated heat meter on the heating circuit. The outdoor temperature was about 10°C (50°F) during the day and 2°C (36°F) at night. So even here, it doesn’t pay off.
The only really sensible way to use solar electricity for heating is with a heat pump, which stores heat in a buffer tank during the day when there is enough sunlight, operating with a coefficient of performance of 3 or higher.
Putting aside all theoretical calculations, I have serious concerns that the usage profile of a battery storage system does not align with the load profile of night storage heaters, which would massively shorten the battery’s lifespan.
H
hampshire18 Dec 2019 23:50When does the sun shine?
When do you need the heating?
Spot the mistake.
When do you need the heating?
Spot the mistake.
Fortunately, a photovoltaic system purchased at a reasonable price is a profitable investment on its own, as long as you don’t ruin it by adding storage. Self-consumption is the cherry on top and helps achieve even faster payback. However, you can safely exclude winter from the calculation since very little sunlight reaches the roof then.
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goalkeeper19 Dec 2019 07:50From a non-expert perspective, wouldn’t it make more sense to invest in a new heating system instead of a photovoltaic system?
H
hampshire19 Dec 2019 09:31goalkeeper schrieb:
Wouldn’t it make more sense from a non-expert perspective to invest in a new heating system instead of a photovoltaic system?If it is a liquidity-related "either-or" question, it can certainly be calculated once. If not: The investment in a photovoltaic system on almost every house makes sense – regardless of the heating system.
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