Doing my personal retro of this year: My parents heatpump + PV + storage produced *total* power costs of ca 600€ (since mid march 2022). That includes ca 5.500 km driven in their car and replacing roughly 3.000l of heating oil. If you include power not bought for house/heatpump, heating oil not bought and car fuel not bought it adds up to savings of 3.300€ - and that's if one bought oil at a cheap pricepoint. At the highest: 7.000€ saved :D Got to say, my regret for heavily recommending this type of setup is rather low now.