I would suggest either of two scenarios:
1) Remove the battery(s) and connect them to a "smart" trickle charger, or
2) Start your solar installation with a 100 -150 watt panel on the roof. Then add to that as your budget allows.
Leaving lead acid batteries to sit idle without cycling/conditioning charging to discharge below 12volts is their death knell. Keep a charge going into them and they will serve you well.
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