You can still totally offset your own actual consumption at retail rate, but any negative over your actual consumption for the month, you only get paid cash at wholesale rate?
Without knowing anything about this or any context... that does not seem unreasonable to me.
Note that OP didn't even require net negative at all to have it still totally be a great investment. He only offest a portion of his actual usage. So net negative paid only at wholesale rate seems like it should still be functional economically and leave plenty of incentive. Wouldn't have effected OP at all, for those who do go net negative and it effects, it seems like it shouldn't tip the scales.