When reporting income from Solar Renewable Energy Credits (SRECs) to the IRS, you should use the gross value of the income received from the sale of SRECs. This means you report the total amount before deducting any brokerage fees or other expenses.
Even you don't receive a 1099-MISC from the brokers, you can still report this income under "Other Reportable Income" on your tax return:
Steps to Report SREC Income in TurboTax without a 1099-MISC
For more detailed guidance, you can refer to the IRS's Frequently Asked Questions about Energy-Efficient Home Improvements and Residential Clean Energy Pro.