ᐅ Cost-effectiveness Analysis of Heat Pump / Ice Storage / Photovoltaic Systems

Hello everyone,

I have a detached house (built in 2018) with underfloor heating that runs on gas. I am considering a personal "energy transition" in the future. My question is whether and when it makes sense financially.

Currently, I pay about 5,000 € per year for gas (11,600 kWh/year) and electricity (3,600 kWh/year) with the local utility. About two years ago, I got a quote for a photovoltaic system (22.62 kWp, east/west orientation) including a battery storage (9.6 kWh). At that time, the system cost around 25,000 €. Do you have experience with when such a system becomes cost-effective? I would like to do the calculations myself (using Excel).

The main challenge is probably replacing the heating, or more precisely, the gas consumption. Has anyone had experience with ice storage systems? Are there better alternatives?

Thank you very much for your help!

NorbT schrieb:

Currently, I pay around €5,000 per year for gas (11,600 kWh/year) and electricity (3,600 kWh/year) from the municipal utilities.

Crazy! Normally, 11,600 kWh of gas costs about €1,000 per year, and 3,600 kWh of electricity around €1,300 per year. Something is definitely wrong with your price.

NorbT schrieb:

The problem is certainly replacing the heating or gas more or less.

No, the problem is your price per kWh or an incorrect calculation.

NorbT schrieb:

Has anyone had experience with ice storage systems? Are there better alternatives?

Almost anything is better for a standard single-family home. For a building from 2018, the only financially sensible solution is to stick with gas. Gas prices would have to rise dramatically for you to recover the cost of a new heating system through savings on heating expenses.

Hello,
unfortunately, this topic is often over-discussed and tends to attract trolls and ideologues of all kinds.
My conclusion is: The outcome of a cost-effectiveness analysis largely depends on the underlying assumptions about future developments. In that sense, you can always get the result you want.
For your case, my advice/recommendation is as follows:
1. Do not mix technical systems. Consider photovoltaic (PV) and heating separately. Regular PV systems do not produce nearly enough electricity in winter to significantly power a heat pump.
2. If your heating system is not already broken, do not replace it.
3. If your energy consumption (kWh) is accurate, you do not have a major problem and can switch to a basic air-to-water heat pump later if technically necessary (an ice storage system is completely unnecessary in your case and only increases costs and complexity unnecessarily).
4. Photovoltaic systems should now be cheaper because the prices for modules and batteries have dropped, and tradespeople no longer have waiting times of several months to over a year. On the other hand, changes in subsidy conditions are looming with the gas crisis. It is possible that VAT exemptions and feed-in tariffs may be discontinued soon.

nordanney schrieb:

Insane! Normally, 11,600 kWh of gas costs around €1,000 per year, and 3,600 kWh of electricity about €1,300 per year.
Something’s wrong with your price.
No, the problem is your price per kWh or a calculation error.

I looked up my bill from last year again. I pay 38.59 cents per kWh, whereas you mentioned 36.1 cents per kWh above? My gas price is 13.88 cents per kWh. I’m probably paying 2 to 4 cents more per kWh… which provider do you use?

Tolentino schrieb:

Hello,
unfortunately, this topic is often over-discussed and tends to attract trolls and ideologues of all kinds.
My conclusion is: The result of a cost-effectiveness analysis largely depends on the underlying assumptions about future developments. In that sense, you can always get exactly the result you want.
For your case, here is the following advice/recommendation:
1. Do not mix technical systems. Consider photovoltaics and heating separately. Common PV systems do not generate nearly enough electricity in winter to operate heat pumps extensively.
2. If your heating system isn’t already broken, don’t replace it.
3. If your energy consumption (kWh) is accurate, you don’t have a huge problem and can easily switch later to a standard air-to-water heat pump when technically necessary (an ice storage system is completely unnecessary for you and only adds cost and complexity).
4. Photovoltaic systems should now be cheaper because prices for modules and storage units have fallen, and tradespeople no longer have waiting lists of several months to over a year. On the other hand, with the gas situation (Gas Kathi), there might be a shift in funding conditions. It is possible that the VAT exemption and feed-in tariff will be discontinued soon.

Then I’ll keep quiet for now. In my opinion, the cost-effectiveness analysis should be calculated very conservatively. Have you ever created such an analysis yourself?

NorbT schrieb:

I looked up my bill from last year again. I pay 38.59 cents/kWh, and is it 36.1 cents/kWh for you as mentioned above? My gas price is 13.88 cents/kWh. I’m apparently 2 to 4 cents/kWh higher... which provider do you have?

I have a heat pump, so I only pay for electricity. Currently around 26 cents.
The figures I mentioned were just rough estimates based on market data.
How do you arrive at €5,000 per year?
Just the consumption excluding the fixed charge is only about €3,000 for you — there’s still a lot of potential here (Check24 & similar services). Much more than switching to a new heating system. If you save maybe €200 to €300 annually through a more efficient heating system, you can calculate for yourself when an ice storage system costing €30,000 would pay off… which is basically never.

Photovoltaics are a different matter. That needs to be calculated separately and on an individual basis.

My conclusion: Look for new providers. At the same time, you can have a photovoltaic system designed and individually assess if and how it makes sense.