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L16GSY
I also have solar panels and as someone who has had their solar panels for nearly 11 years I can tell you that the amount of electricity you will generate between now and March will be substantially less.
You also have to consider you will be heating your home and generally using far more electricity from the grid than you were in previous months.....unless you have a storage battery, then things may be different for you depending on how much your battery can store and how much you may or may not be drawing from the grid.
From personal experience, my energy usage and therefore the cost more than doubles over the coming months mainly due to my gas heating. However, I will still double my electricity usage during this time (I don't have a battery ☹).
Personally I wouldn't take too much of the credit you have built up as it is very likely you will see your DD increase.
For me, I'd much rather keep my DDs lower than pay double or more than what I'm paying now.
Like you, I have built up a rather large credit myself and have issued a refund for £500 but that still leaves my account £1160 in credit. Also my DD is lower than it was earlier this year plus I will still have sufficient funds/credit on my account to cover the extra cost that the colder, dark winter months will bring.
Come the end of January I will take another look at my account and reassess the credit on my account. If by then I am not using up or still have a good amount of Credit on my account I will issue another refund but will allow enough credit to top up my DD's until end of March 2023.
This has always worked for me and I have never had an issue getting refunded but then I never request more than £500 at a time.
Hope this helps in some way but don't be too quick to empty your account unless you can afford the higher DD each month. The last thing you want right now is to get in to debit especially as we have no idea what will happen over the coming months.