Solar thermal hot water and heating - yes or no

Hello We simply don't know what to do and hope for some advice here. It's about the following: We bought a house built at the end of 1970. It is heated with an oil heating system and there is a 200-liter hot water tank. At the beginning of the year, we refueled 3000 liters of oil and the supplier said that the previous owner also refueled about as much per year. Before, an old lady lived here and, of course, no one knows how much she actually heated. Currently, there are three of us. I would like to have a wood stove because I like the warmth and find it cozy. However, we also want to heat properly and not just have a small fire. Now to the actual topic: We are considering installing a solar system to support heating and hot water preparation. Total costs are about €14,000 after deducting the subsidy. That is quite a lot of money and we are unsure whether it will pay off at all. Possibly, we would then also get a water-carrying stove to fill the buffer tank in winter. What do you think? Is the investment worth it?

Total costs amount to just over €14,000 after deducting the subsidy. That is quite a lot of money and we are unsure whether it will even pay off.

No. Or actually yes, but only your grandchildren will experience that.

Water-bearing fireplaces / stoves are also very complex and expensive. That will not pay off quickly. Even the stove builders advised us all against it. Do you have underfloor heating? Maybe it is initially worth investing in better insulation of the exterior walls or new windows?

Insulate the top floor ceiling and roof, if not done yet. Costs approx. €2000 in EL.

Seal windows and consider glass replacement.

Insulate basement ceiling?

Small things like insulating the roller shutter boxes.

Then get to the heating. This can also be optimized at VERY low cost.

Fireplace only for coziness. Only worthwhile if you have your own forest, a wood gasifier might make sense.

All tips, if old standards are still installed.

Solar thermal will not pay off. Or do you have to heat heavily in summer?

Thanks already for your answers. We have already replaced the windows. Since March, we have used about 500 liters of oil, although we only moved in in June. The heating turns on more often to keep the hot water hot.