Should I invest in solar panels?

To be short, Betteridge's law of headlines says very explicitly: No. But damn if they don't it sound tempting.

And despite previous post critisizing current renewable energy situation I still feel very tempted. If, for nothing else then for my own curiosity's sake.

But to expand a bit, I have a summer home, with running municipal water. Since it gets very cold here in winters this means that I need to spend a lot of electricity to heat the cottage even when I'm not there - emptying the water system is pretty much impossible. This being a bit remote location means that this isn't cheap.

My dad however has been encouraging me to get a few panels, 5 or so maybe, to aid with heating there. I'm guessing he'd like to have few panels of his own, too, in same order. The problem is that I've done the math and it doesn't look good.

The main problem is insolation. The word essentially means the amount of solar energy that reaches the ground. I don't have the hard numbers of insolation around here ("here" being close to 65 degrees northern latitude), but I do have numbes for Helsinki (60 degrees north). Up here the numbers are certainly even worse. Unfortunately I don't know how much worse exactly but I've assumed 60% of Helsinki figures in calculations below during the darkest time of the year.

Assuming six panels, 0.91m², each with 140W nominal power the numbers come out as follows:

October: 379 kWh total over month
November: 89 kWh
December: 8.5 kWh (total over the entire month!)
January:  38 kWh
February: 255 kWh
March: 742 kWh

In other words, during the darkest and coldest period of the year the production is practically nothing. But for other months the figures start to look a bit better - during spring and fall there should be enough power to cover at least some of the heating - at least during sunny days.

During summer there is no need heating so savings there are close to zero, aside water heating (granted, that takes a fair bit of energy) and possibly refrigerator (no idea how well it would work during nights as sun doesn't really fully settle).

Now to the main problem again: energy storage. Grid-tie system is completely insane option here - I'd end up paying for each kWh I provide to the grid. So that's out immediately (and that isn't storage anyway, from broader perspective, it's just externalizing the storage problem to someone else).

Battery storage doesn't really make much sense in this situation either; a battery or a few could store enough energy for lights but not much else. So having batteries isn't actually worth the cost or trouble. But at least that would cut off one expensive part (batteries) from the system.

So let's say that I just use panels with inverter connected directly to them. Then there is the problem with brown-outs: I have no idea how inverter would work when usage is greater than what panels can provide. Not well, I fear. I've tried to find out that behavior conveniently seems to be left out from easily available documents.

On the other hand, at summer panels could provide more than 2000 kWh per month. The question is, then, what could I do with all that power. And unfortunately answer is pretty resounding "nothing". Some of that energy I could use when I'm there, but the remaining would pretty much go to waste, short of some ingenious personal fuel refinery gadget (no, those don't exist but man can dream, right?)

But still... It'd be a fun experiment, anyway, even if it wouldn't make any real economical sense.

And yes, I do realize that situation here is completely different than in south where air conditioning is major power hog. For that solar, even now, makes perfect sense. But even then there's still those 12 hours per day there without any solar power...