solarken
NABCEP PVIP
- Location
- Hudson, OH, USA
- Occupation
- Solar Design and Installation Professional
It seems a 10kWh battery might work, and I am attaching a PVWatts sim report for 10 x 430W module array, rooftop south-facing at 20deg tilt that shows the worst month is December with 353kWh produced, or 353 / 31 days = 11.4kWh per day. With your safety margin and assuming not much snow it might be sized right. You would need to add a transfer switch or microgrid interconnect device or inverter with MID, with the battery, and so significant cost.
If there is occupancy sensor in the building the interior lights could be on less, but on a cold day, it seems like the boiler could be on longer to keep the water hot, especially if lots of users. If you have an existing similar bathroom somewhere that you could instrument to see what the energy usage is for things like that this time of year, maybe it would inform you.
If there is occupancy sensor in the building the interior lights could be on less, but on a cold day, it seems like the boiler could be on longer to keep the water hot, especially if lots of users. If you have an existing similar bathroom somewhere that you could instrument to see what the energy usage is for things like that this time of year, maybe it would inform you.