The Reason Those Roofs Are Empty
It is not the economics. It is the lease.
Drive past any industrial park and count the bare roofs. The arithmetic of rooftop solar has worked for a decade, so the explanation is not economic. It is contractual. Under a triple-net lease the tenant pays the electricity bill, which means the savings from an array accrue to the tenant — while the capital, the roof penetrations, the warranty questions and the twenty-year commitment all belong to the landlord.
No rational owner funds an improvement whose entire benefit is assigned to somebody else. No sensible tenant funds a permanent improvement to a building they may vacate in five years. So the roof stays empty, and both parties are behaving perfectly reasonably. Economists call this the split incentive. Landlords call it Tuesday.
No rational owner funds an improvement whose entire benefit is assigned to somebody else.
The arrangement that breaks the deadlock is older than solar: a landlord leases a surface and collects rent. We pay you for the roof. Your tenant, should they want the power, buys it from us separately at a discount to the utility tariff — or does not, in which case the output goes to the grid or to a community-solar programme and nothing whatever about your tenant's bill changes. Neither of you funds anything. Neither of you is asked to subsidise the other. The split incentive does not need to be solved so much as sidestepped.