I would be really cautious about taking a 2nd position lien. If the buyers default to the primary mortgage-holder, and they lose the place, it could very well be sold for only what is owed to the primary mortgage-holder, leaving you out in the cold.
We have sold our property on an OWC wrap-around contract, and it's working very well. We actually did it twice, as the first buyer had to change plans suddenly due to a health crisis. So we sold to first buyer, with $20,000 down, and did all our own paperwork, no interest, deed stays in our name until buyer has completed payoff, we continue to pay property taxes until then as well. A 3-year contract with large monthly payments, and quarterly balloon payments, too. We made the selling price high enough to cover all our interest over the next 3 years, plus our price point, so it came out well, and the buyer's appreciated the no-interest concept. Much more straightforward than amortizing (not that I'm against amortizing). A week later, buyer got a cancer diagnosis (he is only 25 years old!), and immediately re-listed property on craigslist, basically same terms. Within a week, new buyer came along, cashed out first buyer (actually gave him $25k), and gave us the next upcoming quarterly payment immediately as a down to us (another $20k), and basically took over the rest of the contract to us.
So, we are in the first position to foreclose on them, we retain the deed in our name, which would make foreclosure faster and easier should the need arise. I would NOT have done this deal with us in the secondary position, because that only gives you any "leftovers" in the event of a default, doesn't give you the property back, and I do not believe a secondary lien holder can initiate a foreclosure, either.
Anyway, there's lots of info on OWC, and you can usually find state-specific info on the blogs of real estate lawyers.
By the way, what is a "feed in Tariff PV system" ?
MouseBandit