ᐅ Photovoltaic System: Costs and Savings Potential – Experiences?

halmi schrieb:

The calculation is completely nonsensical.

seat88 schrieb:

Utter nonsense.

Why be so unfriendly?

What is unfriendly about the word nonsense?

Thank you for your reply.

hampshire schrieb:

...
Your calculations are roughly correct but quite incomplete and therefore not very realistic.
You still need to consider at least 2 more factors:
...
What is certain: A photovoltaic system is in most cases a very profitable investment.

I would fully agree with that. However, most solar installers currently offer systems with 9.9 kWp and a battery for around 20,000 (net), which often doesn’t make much sense.

I have seen 5 offers recently, ranging from significantly overpriced to expensive and *not reasonable* (*not suitable for the demand and situation*).
One was acceptable but not "optimal."

The advice to check relevant forums has already been given and should be taken seriously. The 20,000 – 30,000 amount that may be invested usually pays off (assuming the system is not grossly overpriced).

Rule 1: Fill the roof.
Rule 2: Fill the roof.
Rule 3: A battery is more of a luxury but can be justified with arguments of energy independence and ecology.

Try to understand what photovoltaics can and cannot do.

If using storage, a basic rule of thumb is: install twice as many kWp on the roof as the battery capacity in kWh.

Everyone has different priorities. An exclusively financial assessment is certainly valid, but is that what you really want?

Consider what a comprehensive concept might look like with a BEV combined with 25 kWp + about 16 kWh battery. Think about tax benefits, environmental impact, and economics.

(With 25 kWp, you will usually have to cover the "less favorable" north side as well; at a roof pitch of 35° and northeast orientation, PVGIS estimates about 65% of the southwest output, which spreads the photovoltaic yield more evenly throughout the day and counteracts the 50% rule (when battery storage is involved)).

P.S. For a single-family house, only 2,600 kWh for the air-to-water heat pump seems set very low, but it might work. The rest of the electricity consumption also appears to be quite low to me.

halmi schrieb:

Try combining self-consumption with feed-in tariff.

I have now done some deeper research and understand that we are currently in a transition phase... Moving away from feeding electricity into the grid towards almost complete self-consumption with the help of a storage system.

At the moment, battery storage is still too expensive, so feeding electricity into the grid remains (and will remain in the medium term) more economical.

Our initial idea was to become completely independent from external energy supply. Maybe that will only be possible in the coming years – the topic of retrofitting battery storage.

hampshire schrieb:

1. Your electricity load profile: When during the year do you need more electricity, and when do you have more electricity generation from your photovoltaic system? I have yet to see a household where electricity consumption is not significantly higher in winter than in summer. On the other hand, the output from the photovoltaic system is much higher in summer than in winter. As a result, you will not be able to cover your electricity demand during winter and will have overproduction in summer. Which brings us to:

2. For the surplus electricity, you receive a feed-in tariff of – let’s say – 9 cents/kWh. That means you have income during the summer months.

The offer of 13,000 for a 6.83 kWp system seems high. What exactly does it include? Others here in the forum have installed significantly larger systems for the same amount.
Also, the electricity price including the meter seems a bit high – especially since you can probably get a heat pump tariff that makes financial sense.

What is certain: a photovoltaic system is in most cases a very profitable investment.

We don’t have any offer yet. I just wanted to roughly calculate what it would mean financially to include a photovoltaic system in our overall concept. The 13,000 comes from the internet and I think includes installation and possibly battery storage (?).

After further research, I would rather estimate a 7 kWp system for 8,500 EUR (including installation). More realistic?

superzapp schrieb:

P.S. For a single-family home, only 2,600 kWh for the air-to-water heat pump seems set very low to me, but it could work. The rest of the electricity consumption also seems very low.

Thanks for your input. I took that into account and now estimate 6,000 kWh (currently we use 2,600 kWh general electricity for two people without the heat pump).

Based on your feedback, I would adjust my calculation as follows:

Parameters:
- 7 kWp photovoltaic system for 8,500 EUR including installation (= portion of loan annuity with house bank loan: 26 EUR)
- Annual maintenance costs 420 EUR
- Annual photovoltaic production: 850 kWh/kWp = 5,950 kWh
- Total consumption 6,000 kWh; of which 2,600 kWh for heat pump
- Assumed self-consumption rate: 45%
- Feed-in tariff: 8 cents/kWh (since completion of single-family house planned for 11/2021)
- Heat pump electricity tariff: fixed charge 90 EUR/year; 20 cents/kWh
- General electricity tariff: fixed charge 150 EUR/year; 29 cents/kWh
- Tax considerations are initially excluded

Annual total costs with photovoltaic system:
- Loan annuity 312 EUR
- Maintenance costs 420 EUR
- Heat pump electricity tariff: 90 EUR + 413 EUR (2,600 kWh – 536 kWh* × 0.20 EUR)
- General electricity tariff: 150 EUR + 365 EUR (3,400 kWh – 2,142 kWh* × 0.29 EUR)

*Photovoltaic system production 5,950 kWh
of which fed into grid: 55% = 3,273 kWh
self-consumption: 45% = 2,678 kWh (of this, 20% for heat pump; 80% general electricity)

= 1,750 EUR minus 262 EUR (feed-in tariff 3,273 × 8 cents) = 1,488 EUR (124 EUR/month)

Annual total costs without photovoltaic system:
- Heat pump electricity tariff: 90 EUR + 520 EUR (2,600 kWh × 0.20 EUR)
- General electricity tariff: 150 EUR + 986 EUR (3,400 kWh × 0.29 EUR)

= 1,746 EUR (146 EUR/month)

Advantage of photovoltaic system:
258 EUR per year or 22 EUR per month.

If your roof is only large enough for a 7 kWp system, then yes, otherwise the roof is full. This has already been mentioned here. Your roof generates income. The larger the system, the lower the price per kWp. In my opinion, maintenance costs of €420 (about $450) per year are far too high. What exactly do you want to maintain? Don’t forget to get photovoltaic insurance, which costs around €50-70 (about $55-75) per year. Also, make sure your personal liability insurance covers photovoltaic systems in case any panels are damaged and cause harm to others.

Run the heat pump on your household electricity. That saves you from paying for a second meter. You can also get general electricity for less than your 29 cents per kWh. For example, since early May I have been paying €0.2293 per kWh (about 23 cents). Always remember to switch providers and take advantage of any bonuses.