Thanks for the feedback. I may have had the same buy and sell values all along (peak and off-peak were more realistic at the start of my tests). I'll try using the values you suggest and report back. That said, things like draining the PW when the grid cost is $0.01, or nor sending solar to the grid when it sells for $1.50 doesn't make a lot of sense. Those look like software logic issues.I agree with Redhill.
Although, while 0.01 for buy may be close to realistic for what the OP indicated the utility is charging (since I think the OP said they have zero charge for offpeak), like Redhill mentioned, I think to force the PW behavior the OP wants they'd want to fill in a higher number for Buy, say like 0.10 or higher, and for the sell side the OP should set a very much lower number, so could leave it at 0.01... those values should tell the PW that it doesn't make sense to sell back to the grid since the sell is so much lower than the buy. The closer those buy/sell values are, the less predictable it will be what the system does in terms of buying/selling power.
My experience has been that if the system sees a similar buy and sell, and if the system predicts any extra PV capacity (whether accurate or not), then most likely it will think it makes sense to offset usage by selling back to the grid if the costs are even close to similar (for buy and sell). I've never used 0.01 for buy and sell, but when I've set BOTH buy and sell values to be equal at around 4-5 cents, it has always tried to sell back to the grid for even the off-peak windows. Where as if buy is much higher than sell, then the system sees no benefit to selling power back to grid then it will focus on powering the house and/or raising the PW SOC.
So with BOTH buy and sell values set to 0.01 it's not surprising to me that the system was selling back to the grid based on my experience, even though selling for a single penny does seem ridiculous for sure relative to the OPs peak costs.