ᐅ Recommendations and Experiences with Solar Power Systems

Hello,

soon, a solar system to support the gas boiler will be installed on the roof of my new building. Currently, 2 people live in the house, but in the future, 2 more will likely join.

I am quite unsure about the size. Maybe you can share what you have chosen and your experiences with it?

I am considering 2 options:
Option 1: 3 collectors on the roof and a 400-liter (105-gallon) hot water storage tank in the basement. This would probably be the most cost-effective solution. However, I have concerns because a relatively large amount of fresh water is stored in the tank. With 2 people, it takes quite a while for the water to be fully replaced. Also, a hot water storage tank does not allow for heating support (although I am not yet sure if that is really cost-effective). It is also uncertain whether this solution can bridge a period of bad weather.

Option 2: 4 collectors on the roof and a 1000-liter (265-gallon) buffer storage tank with a hot water module. This is the more expensive and complex solution. However, I would not have hygiene concerns with this one. Heating support would also be possible. A period of bad weather would likely be better managed. But if it stays hot for a longer time, I might have problems storing the excess heat somewhere. That would also probably not be ideal for the panels on the roof...

What are your experiences? How long does your hot water last when the sun is not shining?

Best regards and thanks in advance!

Simple answer: The cheapest and smallest option you can get that meets the legal requirements. Solar thermal systems are never economical and only take up unnecessary space compared to the much better photovoltaic systems.

rastlos schrieb:


I am considering two options:
Option 1: 3 collectors on the roof and a 400-liter (105-gallon) hot water storage tank in the basement. This would probably be the most cost-effective solution. However, I have some concerns because there is quite a large amount of fresh water stored. With two people, it takes a long time to fully exchange the water in the tank. Also, a hot water storage tank does not allow for heating system support (although I’m not yet sure if that is truly cost-effective). It’s also uncertain whether this solution can cover cloudy weather periods.

Option 2: 4 collectors on the roof and a 1000-liter (265-gallon) buffer tank with a hot water module. This is the more expensive and complex solution. On the plus side, I do not have to worry about hygiene issues. Heating system support would be possible. Cloudy weather periods would likely be better managed. However, if there is a long heat wave, I might have problems storing the excess heat. This might not be ideal for the roof collectors either...

Neither of these options.

Option 3: A vacuum tube collector (better efficiency under diffuse light and during transitional seasons) and a 300-liter (79-gallon) hot water storage tank without heating system support.

I can only agree with that. 300 liters (79 gallons) are also completely sufficient for 4 people.

We have two panels and a 300-liter (79-gallon) storage tank. The system provides hot water for both of us from April until mid-October on its own, and I turn off the boiler’s hot water during that period. In December, however, only the boiler is running, as the solar system produces almost nothing since the sun barely rises above the horizon. The system starts working again around mid-February. It operates reliably and seems to be a well-developed technology. That’s all we need.

So definitely no buffer tank with heating support?

But that would definitely rule out a possible combination with a photovoltaic system.

@Mycraft: How long does your hot water last? And from when to when does the system operate for you?