Though, the government does have this type of energy tax credit for homeowners and it is 30 percent of the project cost or up to $1,500--but it is not for businesses.
Since you own a restaurant you will be hard pressed to find a government energy tax credit for your business, but you may find this list on the IRS website to be helpful.
Also, if you are interested in other tax credits available to businesses there is the Work Opportunity Tax Credit. This tax credit is issued to employers that hire individuals unable to gain employment because of significant barriers. Generally, the tax credit is 40 percent of the first $6,000 in first year wages or $2,400.
Good luck and continue working on being green. Every bit helps.