Agreed price is a strong signal, but price *of what* is important especially with solar. When it comes to electricity, one must take into account reliability/availability. The metric I most recommend is not cost per MW installed (nameplate,) but one that takes into account the costs of baseload generators (e.g. gas turbines) to support variable generators (solar or wind) to incorporate reliability across a regional grid, inclusive of the cost for capacity reservations, diversification of location, etc., called the “Levelized Full System Cost of Electricity” to get to 95% reliability, for example.