Are Swiss solar PV auctions well-designed and how can they be improved?

Auctions for renewable energy support have become the standard way to give out subsidies to solar energy projects and other renewables in Europe. In an auction, investors usually compete to receive the subsidy based on their offered support price, where the bidders with the lowest offered prices win. The Swiss government has started using auctions to award investment subsidies to larger PV projects. Are the auctions designed well and fit for purpose? How have the auctions performed until now?