What state and zip code regulates you ?
Aside from my meter charges, last year I was at virtually 100% for the entire year. First 5 months I bank the excess, and then spend the rest of the year using it up. Got to net-zero about Oct. For 20 kw I needed two meters and panels. So $22 a month for each. So the grid connect amounts to about $500 a year, for the luxury of using the grid as my ‘battery bank’
If we lose power I got 28 kw of LiFeP04 cells. 2 banks of 17 cells each, 280 ah
XW6848
I'm in central Alabama, regulated by Alabama Power (the lower 2/3rds or so of the state).
If I was to put power onto the grid without signing a purchase plan agreement, the utility would automatically sign me up for their default power purchase plan which would add the "solar fee" of $5.41 X inverter nameplate capacity per month. In my case that would be $5.41 X 24 = $129.84, with a 4% state tax on top it'd be $135.03/month added to my bill just for the privilege of them buying back power from me at 3¢ to 4¢ per kWh (depending on the season, which is 1/5th to 1/4th as much as we pay them per kWh after adding the riders and state tax they charge us).
There is another "solar fee" you can choose to pay which is the route I'm going. That's based on the highest power demand you had that month ($1.50 X highest kW draw from the grid, plus 4% state tax). One reason I'm only now signing up for it is because I didn't know how much that would be (I didn't know the max kW grid pull each month), especially with the extra demand of charging an EV and, in extreme temp cases, keeping the house cool in the summer during 100F weather days or keeping the house warm during below freezing days. As of now, I've got the experience of going through my first winter after my recent solar upgrade in late August last year. I also now have the experience of the power demand of charging the EV for a year. And fortunately, my inverters have an exhaustive data export recording at 5-minute candles, including how much power was pulled from the grid at those moments. I use a homemade C# app to import that data into a homemade SQL Server database so I can analyze it and run simulations on what my past 12 power bills would have been like with the different rate plans I can choose from. Thus I've decided on the power purchase rate plan with the demand charge "solar fee". The second cheapest rate plan is to keep doing like I'm doing with no power purchase (no putting power onto the grid) and staying on the default family dwelling rate plan almost every residential customer is on. The difference between the two rate plans is about $200-$250 per year in favor of the purchase plan. So from April to November I'll have either no power bills or, possibly a small power bill in April, and/or May, and/or November (with November sometimes using up all of my credit built up from selling power to the grid during the spring through fall months). Then December through March I'll have power bills totaling $550-$600 (with March being maybe $35, and December somewhat low at around $100 to $150, depending on how much buyback credit was leftover after the November bill, and January and February being the only months in the year that'll always have high bills). Thus, the utility won't buy back power at near the rate that they charge me for what little power I buy from them (we don't have net metering). But in my particular solar system and power consumption habits, what the utility pays me for my power will more than offset the extra fee they'll charge me for the privilege of selling them cheap power.
Another regulation with putting power onto the grid is that most people have to have a shut off switch to automatically shut down your solar power and battery power if the grid went down (to keep from harming linemen working on downed lines, which is understandable). Thus if the neighborhood's power is out mine would have to be out too even if I've got plenty of sun (or battery storage) to power my home. My inverters, however, allow me to bypass that rule because my inverters can detect the grid down and not put power onto the grid even while supplying power to my house. So when the few times the grid is down (our grid power is pretty dependable, unlike 3rd world California), I still have power in my house. That won't change if I sign up for the power purchase plan. Thus I'll have the best of all worlds of solar: it can keep providing me power when the grid is down and also lower my power bills mainly by virtue of providing most of the power I need anyway, and also lower my power bills further by selling excess power to the grid.