Flat collector vs tube collector

-Thanks for the additional tip, I actually first thought "Guerilla Photovoltaics" was a joke because of the suspicious name. I clicked on it anyway and found it interesting. Apparently, you can start small, which is appealing for "tinkerers." --- I will do some research. -... I do understand, in winter there is no warm collector water, while photovoltaics help in that case. Of course, everything pays off eventually. The core question for most users is always the amortization factor, which is always individually different regardless of the actual time. If I am an "environmental freak" (not meant negatively), time doesn't matter to me, and I know I am ahead of time in a good way and am willing to open my wallet today. Others look at the account and ask themselves "what will it be in 10 years," would rather sit in the garden now with friends and crack open a few bottles of champagne "Chateau Lafite Rothschild south-facing" (the one with the earthy finish) ;-) or invest in the future. Besides, you have to have it left over. Many (who have it installed unregulated right away in their new houses) will soon notice that some things have to be paid off quite laboriously afterwards, and the money recirculation machine doesn't run that smoothly. (Hopefully, the commitments were not time-limited and won't be adjusted again after a few years - this has all happened before) Who knows what tomorrow will bring (at the moment our "peace angels" are itching again to cancel contracts and upgrade as quickly as possible, but that does not belong here). Heat or electricity, which we all don't want to do without, is a large field. I have also already researched heat pumps and mini combined heat and power plants, from which my overall skepticism results. If you want to compare everything properly (heat pumps air/water/deep drilling/shallow burial - combined heat and power plant - electricity/heat - solar collector flat/tube), you really have to be retired and have enough time to make a sensible decision. (if retired, not with the "minimum pension" - sorry for the bad joke) My information obtained in the past from "specialist companies" mostly turned out to be problematic. For example, click on the "free energy consultations" - that always 100% results in them having our data and the consultants in the house. These are professionals who work for commissions. This is not to criticize since we all work for money, but as to how optimal and correct all statements are, I can only dispute from practice. Therefore, my thread and the plan for a small experimental start. Sorry also for the too long text, but the admin will turn a blind eye, since storage space is not really a problem these days. First, greetings from SKF (FutureSkepsisMan), the one with the small experimental start :-)

So I have both, solar thermal and photovoltaic - and I don't agree at all with this "either-or" belief war.

Both have their pros and cons (especially if you don't have a heat pump as a heating system; with a heat pump you can omit solar thermal and fully rely on photovoltaic) and I would now very much like to write pages about it, but my child is demanding to be put to bed ;-)

That's why I will now (I think the only one in this thread so far) briefly address the ORIGINAL QUESTION of the OP: If solar thermal, then take a vacuum tube collector. A bit more expensive, but significantly better and more effective. Especially when the sun shines at an angle/sideways on the collector, the vacuum tubes deliver SIGNIFICANTLY better results thanks to the parabolic mirrors - also during the transitional periods.

short addendum: With a small guerrilla photovoltaic system, you won't get a heat pump or an electric heater for hot water running... you need a bit more photovoltaic than just one or two modules for that... and personally, I wouldn't put myself through that, installing something illegal on the roof.

Our general contractor would have preferred to install solar thermal systems. Why? Because that is what he has always done so far. Basically, there is nothing against ST, provided the investment is low. Our energy consultant then calculated the annual savings in our case: about €120/year. It would therefore take 100 years to recoup the investment costs. Now we are planning a photovoltaic system, which takes about 10 years.

ST does have an additional cost of around 2800 gross. With a saving of 120 euros per year, that's a bit over 20 years, not 100. You're right, if you really calculate, all this eco stuff isn't worth it, but the energy saving ordinance applies anyway.

A bit late, but I hope it still helps. I have had 4.4 m² tube collectors facing east and geothermal energy for 15 years with 300l. When the sun shines, the boiler heats up relatively quickly; in winter I get a maximum of 30-35°, which is too little for showering. If I had 20 collectors, I would have 3000l at 30°, but still useless. Your 80l are far too little, enough just for one shower, and every small collector fills it up. After 10 years I had one defect, a "scaling," but luckily I can repair it myself without a scaffold. Therefore tubes 4m² and larger boiler (3-500l) or guerilla and heat pump boiler.