Several states have considered laws that would require retailers to provide advertised rebates to customers at the time of the purchase with no strings attached.

The 10-kilowatt model costs about $45,000, though some states, including New York, provide rebates that can cover half the cost or more.

However, consumption taxes such as a sales tax can often exclude items or provide rebates in an effort to create social justice.

These powers had been used to provide one-off rebates and concessions on a number of occasions under special circumstances in recent years.

Insurers that don't meet these thresholds must provide rebates to policyholders.

One provision requires insurers that spend less than 80 percent of premiums on health care services to provide rebates to consumers.

Drug makers are required by law to provide rebates to state Medicaid programs for low-income people, based on the "best price" they charge other purchasers.

Washington state provides utility grants, loans and rebates for wind power.

"The biggest problem is companies' providing rebates late or not at all," he said.

If insurance companies do not meet these goals because their administrative costs or profits are too high, they must provide rebates to consumers.