ᐅ Heating System Question for New Build KfW 70: Air Source Heat Pump + Solar, Ice Storage?
Created on: 24 Feb 2015 11:42
H
hiasl86
Hello dear forum users!
We are currently planning a new build in southern Bavaria near the border with Salzburg. At the moment, we are looking for the right heating system for our home. We have a living area of about 140 sqm (1507 sq ft). We plan to build to KfW 70 standard (36 cm (14 inch) bricks with perlite filling).
What we definitely do not want is oil heating. Gas is also not an option for us since there is no connection available, and I do not want to have a gas tank buried in the garden. We also don’t really want a pellet heating system because of the required storage space.
We are actually leaning towards a heat pump. We initially wanted geothermal energy with a deep borehole (ground collectors are not feasible due to limited land area). We received an offer for the deep drilling, but to me, it seems very expensive (12,000 - 15,000 Euro). The problem is that the water management authority limits the drilling depth to 10 m (33 ft). This is partly because sulfate rock was found nearby at depths of 30–40 m (98–131 ft), and no drilling has been done directly in our neighborhood yet. The drilling company suggested drilling 9 times to 10 m (33 ft) as a safe option. The less certain option (1. due to permits and 2. because it is unclear how far you can actually drill) would be 4 times 23 m (75 ft).
Now we might consider switching to an air-to-water heat pump with solar support (for domestic hot water and heating assistance). What do you think about this combination? How effective is it and what about electricity consumption? How well do air-to-water heat pumps perform in winter on very cold days? What investment costs should we expect roughly?
We also came across the solar heat pump system, combining solar, air, heat pump, and ice storage. Has anyone had experience with such a system? How does it perform in winter? Is it possible that you might end up heating only with electricity if the ice storage freezes too early and cannot thaw quickly enough, or is the solar and air energy usually sufficient? What about investment costs—how much higher are they compared to the solar plus air-to-water heat pump version?
I have browsed quite a few forums looking for answers and experiences with ice storage. Opinions seem quite divided (too early freezing, not cost-effective due to high investment costs).
Thank you in advance for your help and advice!
Best regards
Matthias
We are currently planning a new build in southern Bavaria near the border with Salzburg. At the moment, we are looking for the right heating system for our home. We have a living area of about 140 sqm (1507 sq ft). We plan to build to KfW 70 standard (36 cm (14 inch) bricks with perlite filling).
What we definitely do not want is oil heating. Gas is also not an option for us since there is no connection available, and I do not want to have a gas tank buried in the garden. We also don’t really want a pellet heating system because of the required storage space.
We are actually leaning towards a heat pump. We initially wanted geothermal energy with a deep borehole (ground collectors are not feasible due to limited land area). We received an offer for the deep drilling, but to me, it seems very expensive (12,000 - 15,000 Euro). The problem is that the water management authority limits the drilling depth to 10 m (33 ft). This is partly because sulfate rock was found nearby at depths of 30–40 m (98–131 ft), and no drilling has been done directly in our neighborhood yet. The drilling company suggested drilling 9 times to 10 m (33 ft) as a safe option. The less certain option (1. due to permits and 2. because it is unclear how far you can actually drill) would be 4 times 23 m (75 ft).
Now we might consider switching to an air-to-water heat pump with solar support (for domestic hot water and heating assistance). What do you think about this combination? How effective is it and what about electricity consumption? How well do air-to-water heat pumps perform in winter on very cold days? What investment costs should we expect roughly?
We also came across the solar heat pump system, combining solar, air, heat pump, and ice storage. Has anyone had experience with such a system? How does it perform in winter? Is it possible that you might end up heating only with electricity if the ice storage freezes too early and cannot thaw quickly enough, or is the solar and air energy usually sufficient? What about investment costs—how much higher are they compared to the solar plus air-to-water heat pump version?
I have browsed quite a few forums looking for answers and experiences with ice storage. Opinions seem quite divided (too early freezing, not cost-effective due to high investment costs).
Thank you in advance for your help and advice!
Best regards
Matthias
The current compensation rate for systems under 10 kWp is 12 cents per kWh. Around 10 cents are the actual costs for the owner.
One kWp costs about 1,500 euros, and around 20,000 kWh will be generated over 20 years. Including the proportional costs for the inverter, which doesn’t last the full 20 years, this results in about 10 cents per kWh.
I can only share my own data, but everyone should be able to achieve around 30% efficiency, considering that work is done only about 200 days out of 365.
By the way, it’s not necessary to have a warm meal in the evening if you’ve already had one at the cafeteria during lunch.
The costs will be lower during the second 20 years, at about only 1 cent per kWh.
One kWp costs about 1,500 euros, and around 20,000 kWh will be generated over 20 years. Including the proportional costs for the inverter, which doesn’t last the full 20 years, this results in about 10 cents per kWh.
I can only share my own data, but everyone should be able to achieve around 30% efficiency, considering that work is done only about 200 days out of 365.
By the way, it’s not necessary to have a warm meal in the evening if you’ve already had one at the cafeteria during lunch.
The costs will be lower during the second 20 years, at about only 1 cent per kWh.
The calculation doesn’t convince me, as many cost factors seem to be missing (connection, installation, fees? Are all these included in the 1500? Increase in insurance), which would actually make it more expensive. These small expenses add up. Also, many people tend to work a few extra days. And if you go on vacation, maybe during the good weather season, you’re not at home at all, so basically ZERO self-consumption! Overall, this means (considering efficiency also decreases over time) that the fed-in electricity is close to zero. If the small insurance cost over 20 years is only 400 (just 20 per year!), which could also get more expensive, then your cost per kWh increases by about 2 cents, and you end up losing money on the sale! (at 70% of production). Too uncertain, especially if the feed-in tariff decreases...
This is the price per kWp for an installed system of about 5 kWp. There are no small expenses here. The insurance costing 40–50 euros covers the entire system and becomes unnecessary after at most 10 years because the inverter will be outdated by then, and modules are becoming cheaper in case one breaks. There are photovoltaic systems that are over 30 years old and still deliver more than 90% of their original output. On average, employees are sick for 18 days. In Germany, there is also retirement, and many devices consume electricity even when no one is home.
The feed-in tariff applies for 20 years, but electricity prices increase every year. The higher the electricity prices rise, the more profitable photovoltaic systems become each year, thanks to self-consumption.
No, those who do not have photovoltaic systems are to blame themselves.
The feed-in tariff applies for 20 years, but electricity prices increase every year. The higher the electricity prices rise, the more profitable photovoltaic systems become each year, thanks to self-consumption.
No, those who do not have photovoltaic systems are to blame themselves.
No, if you don’t calculate properly, you’re also to blame. In your calculation, you always pick the best-case numbers, neglect maintenance costs, and that just doesn’t add up. You calculate with the cheapest system, the best yield, and the longest durability. A high-quality system can easily cost several thousand euros including installation and everything, maintenance costs can be higher (which you barely mention here), maybe after 10 years someone has to clean it (depending on the location), and so on. That’s wishful thinking, especially when you leave out the “small” detail of 1000 euros for insurance (over 20 years) in your calculation and other things. Stopping insurance after 10 years because modules are cheaper then – in the last 10 years they haven’t become that much cheaper, so that’s pure speculation. Also, and this is what I meant regarding insurance, your household contents/fire insurance, etc., usually becomes more expensive with a solar system. Try telling your insurance company after 10 years that you still have the system but don’t want to pay for insurance anymore. And even if you fudge the numbers, it’s still very close to the feed-in tariff; too close. Since everything is just a rough estimate, you can easily end up with costs of 12 or 14 cents per kWh!
Now explain to me how I’m supposed to generate electric vehicle (EV) charging reasonably while absent. I would be on an island for 3 weeks — how does that work? I think this is very individual for each household whether it’s feasible without battery storage or not, and it’s not as simple as you make it seem. If you now also retrofit or buy new household appliances so it all works, you have to add these costs to the photovoltaic electricity costs, and then it definitely doesn’t pay off anymore (and quickly adds another thousands). By the way, electricity hasn’t become more expensive; the government has only added higher levies like for the feed-in tariff, so end consumers pay more. Therefore, in 20 years (looking into the crystal ball) the feed-in tariff will probably be lower.
Usually, calculations don’t go much beyond 20 years anyway; the system needs to have “paid off” by then, so there’s not much point in calculating beyond this timeframe. Also, it would be too much speculation about what might happen then.
I don’t think you really make a profit with solar or that it really pays off. But at the moment you hardly get any interest on your money, so if you really have money left over, you can put such a system on your roof and it also gives you a good conscience. When you can safely get 4% interest on your money again, you’d benefit more from that than from solar (and it’s much easier).
Now explain to me how I’m supposed to generate electric vehicle (EV) charging reasonably while absent. I would be on an island for 3 weeks — how does that work? I think this is very individual for each household whether it’s feasible without battery storage or not, and it’s not as simple as you make it seem. If you now also retrofit or buy new household appliances so it all works, you have to add these costs to the photovoltaic electricity costs, and then it definitely doesn’t pay off anymore (and quickly adds another thousands). By the way, electricity hasn’t become more expensive; the government has only added higher levies like for the feed-in tariff, so end consumers pay more. Therefore, in 20 years (looking into the crystal ball) the feed-in tariff will probably be lower.
Usually, calculations don’t go much beyond 20 years anyway; the system needs to have “paid off” by then, so there’s not much point in calculating beyond this timeframe. Also, it would be too much speculation about what might happen then.
I don’t think you really make a profit with solar or that it really pays off. But at the moment you hardly get any interest on your money, so if you really have money left over, you can put such a system on your roof and it also gives you a good conscience. When you can safely get 4% interest on your money again, you’d benefit more from that than from solar (and it’s much easier).
N
nordanney7 Dec 2015 07:24Quick question about insurance. Besides household contents insurance, what other insurance do you really need? Usually, that also covers the photovoltaic system, unless you have a cheap contract with hardly any coverage.
Therefore, we don’t have any additional insurance and don’t incur extra costs.
Whether the 10 cents are appropriate is another matter. Just looking at the taxes on self-consumption alone, I’m inclined to doubt it...
Therefore, we don’t have any additional insurance and don’t incur extra costs.
Whether the 10 cents are appropriate is another matter. Just looking at the taxes on self-consumption alone, I’m inclined to doubt it...
Similar topics