Evaluate offer, photovoltaic system technology

I am remote on a plant abroad, that is not an excuse ;) No... a basic quota must always be there. But it cannot be that the cashier sits by candlelight because the electricity price shoots up to 60 cents/kWh, while her neighbor, the CEO, at the same time switches on his sauna and the pool heating, because the 60 cents/kWh are completely irrelevant to him.

I don't want to start a class struggle here - but if we don't have to work dynamically, we simply have to expand massively - that will then be added to the grid fees again. There is no free lunch.

If you’re such a fan of storage, then calculate what it economically brings.

Disclaimer upfront: Since the calculation includes the electricity price, any acquisition of this kind can always only be a "bet," as no one has a crystal ball.

We purchased the storage for around €6800. 12.3 kWh with 7 years warranty. During the warranty period, we therefore have 7*365 days = 2555 days.

According to our experience so far, we can still easily fully charge the storage during the day in September. I’m also optimistic for October since we are currently full at the latest by midday. To simplify, I assume we can fully charge the storage for 3 seasons, and I only count 50% in winter. Since we currently empty the storage every evening/night and we’re not yet in the heating period, I see no problem emptying it throughout the whole year.

3/4 of 2555 days = approx. 1916, with a full cycle per day = 12.3 kWh x 1916 = 23566 kWh 1/4 of 2555 days = approx. 639, with half a cycle per day = 6.15 kWh = 3930 kWh

Totals 27496 kWh that we do not have to draw from the grid at about 39 cents = €10723 Minus €2254.67 lost feed-in tariff = approx. €8469 > €6800 acquisition costs.

I have not considered charging/discharging losses, as I lack sufficient knowledge about them. Even if I subtract another 10% for that, I would still be in the black.

We have bet that: - we can fill the storage more than 50% on average also during the winter months (which would improve the balance) - the electricity price will rise, not fall, over the next 7 years. - the storage will not break down on the day the warranty expires.

How large is your photovoltaic system, and what is the orientation plus roof pitch, for this calculation?

How big is your photovoltaic system, and what is the orientation plus roof pitch for this calculation?

The photovoltaic system is 12.45 kWp. The modules are bifacial. Orientation is hard to say; we have modules on all sides except the north side (our roof is suboptimal for photovoltaics). The calculation is based on previous experience since we moved here. We moved in at the beginning of September; since then, our best value for production was 60 kWh per day. So far, we have always been able to fill the storage completely. Autumn and spring are usually good months for photovoltaics. Winter remains to be seen.

Hello,

That electricity prices will rise is anything but certain. The more green electricity is in the grid, the cheaper it becomes, because operating costs disappear. Wind costs nothing and it also doesn't need to be brought to us by ship from Australia or Venezuela.

I wouldn’t be so sure about that. The electricity generation itself (wind/solar) is free, that’s true. But the necessary investments increase with the rising share of renewables. I always need more power lines and I need more (fossil) backup power plants, which are idle for up to 95% of the year and only needed at a few moments (but then really needed). Near Ingolstadt there is one of the most modern gas turbine power plants in the world. It runs less than 200 (two hundred) hours per year. In the end, someone has to pay for that and all of it is passed on through grid fees.
On top of that come small issues like inflation and similar. The expansion and maintenance of the grid will almost certainly not be cheaper in 20 years than it is today.

In short, I am very, very sure that electricity prices will cheerfully continue to rise. Whether the average over the next 20 years will be closer to 2% per year or rather 10%? I would also like to know that…

Best regards,

Andreas

Hi,

= approx. €8469 > €6800 acquisition costs.

Unfortunately, I have to be a spoilsport again. Your acquisition costs are unfortunately not €6800 but €6800 with interest and compound interest over 7 years. At about 4% currently, that is €8950. With the current electricity prices, you are therefore adding about €500.

Best regards,

Andreas