Hello,
my question is a bit general and probably there is no exact answer. I have a mid-terrace house that is now 28 years old. One roof surface faces south, which I think is suitable for a photovoltaic system. By chance, I saw an offer at a Swedish furniture store for a photovoltaic system (4 kWp) including storage and installation for around 12,000. I always thought something like this would be much more expensive. Our current electricity consumption is 2800 kWh/year, and at some point the old gas heating system will certainly need to be replaced, possibly by a heat pump. Now I wonder: is this price realistic for a photovoltaic system with everything included? I guess scaffolding is needed, or do they maybe install it through the roof window using a harness?
my question is a bit general and probably there is no exact answer. I have a mid-terrace house that is now 28 years old. One roof surface faces south, which I think is suitable for a photovoltaic system. By chance, I saw an offer at a Swedish furniture store for a photovoltaic system (4 kWp) including storage and installation for around 12,000. I always thought something like this would be much more expensive. Our current electricity consumption is 2800 kWh/year, and at some point the old gas heating system will certainly need to be replaced, possibly by a heat pump. Now I wonder: is this price realistic for a photovoltaic system with everything included? I guess scaffolding is needed, or do they maybe install it through the roof window using a harness?
N
nordanney13 May 2024 08:47motorradsilke schrieb:
With a non-financed investment, you still need to offset the interest you would otherwise earn on the invested money.
And with a financed investment, you need to add the interest for the financing. Yep. That’s why it’s set at 10 years. With financing, it usually takes longer because loan costs generally exceed the returns from an investment (excluding things like stock trading, etc.).
I wouldn’t count on too much from a 4 kWp system for a heat pump plus an electric car.
Here’s an example. We have a 12 kWp system without storage. The system is new, and I started tracking performance from February 8th.
For February, the system produced 400 kWh, with 170 kWh self-consumed and 230 kWh fed into the grid. Of the 400 kWh, 150 kWh were generated on three sunny days. February was extremely overcast and very low in sunlight here, but even so, this is just a drop in the bucket for the heat pump (which consumed 600 kWh during the same period). Overall, we currently have a 28% self-consumption rate. Since March, there has been significantly more sun, which lowers self-consumption; on good days, we produce 70 kWh and use 6 kWh in total.
From an economic standpoint, the key is to reduce cost per kWp (usually by fully utilizing the roof space) and then factor in the feed-in tariff / payment.
Our system cost us €1350/kWp.
Here’s an example. We have a 12 kWp system without storage. The system is new, and I started tracking performance from February 8th.
For February, the system produced 400 kWh, with 170 kWh self-consumed and 230 kWh fed into the grid. Of the 400 kWh, 150 kWh were generated on three sunny days. February was extremely overcast and very low in sunlight here, but even so, this is just a drop in the bucket for the heat pump (which consumed 600 kWh during the same period). Overall, we currently have a 28% self-consumption rate. Since March, there has been significantly more sun, which lowers self-consumption; on good days, we produce 70 kWh and use 6 kWh in total.
From an economic standpoint, the key is to reduce cost per kWp (usually by fully utilizing the roof space) and then factor in the feed-in tariff / payment.
Our system cost us €1350/kWp.
We did a rough calculation and found that with realistic self-consumption rates (achievable without excessive effort to increase them, around 20-30%), at current electricity prices it is generally more advantageous to feed all generated power into the grid (for a 10 kWp system, 8.11 vs. 12.87 cents / kWp).
This changes if you assume a moderate increase in electricity prices (e.g., about 4% per year, as seen over the last 20 years) or if the self-consumption rate can be increased somehow. However, there is also an argument against rising electricity prices: the energy transition. If it succeeds, electricity generation will likely become cheaper, with only grid fees increasing. CO2 costs might rise, but these cannot be applied to renewable energy.
So, wait until 2025. If the CDU wins next year and a grand coalition seems likely, it’s better to focus on self-consumption. If the Greens manage to gain power again, full feed-in is preferable – especially if the goal is to create a viable business case.
If you have many roof surfaces facing different directions, you could also register multiple systems. For example, an east-west system for self-consumption and the rest (especially south-facing) for full feed-in.
This changes if you assume a moderate increase in electricity prices (e.g., about 4% per year, as seen over the last 20 years) or if the self-consumption rate can be increased somehow. However, there is also an argument against rising electricity prices: the energy transition. If it succeeds, electricity generation will likely become cheaper, with only grid fees increasing. CO2 costs might rise, but these cannot be applied to renewable energy.
So, wait until 2025. If the CDU wins next year and a grand coalition seems likely, it’s better to focus on self-consumption. If the Greens manage to gain power again, full feed-in is preferable – especially if the goal is to create a viable business case.
If you have many roof surfaces facing different directions, you could also register multiple systems. For example, an east-west system for self-consumption and the rest (especially south-facing) for full feed-in.
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