I recently built an off grid 500 square ft cabin in the mountains and I'm looking to install some solar on a relatively tight budget. The cabin is unattended for months at a time and can get down to -20F in the winter, so I would really like to avoid leaving large batteries there (I would also like to avoid the expense). The cabin has a wood stove for heat, so the main electrical loads would be a heat pump (primarily for cooling in the summer), minifridge, 1-2 burner cooktop, and small lights. I also hope to eventually add an EV charging station. It's insulated nearly to passive house standards, so I imagine there would be no problem running cooling systems only when the sun is out. Cooking and EV charging could also be adjusted to accommodate the sun. I figure roughly 3-4kW of solar would allow level 1 EV charging plus other loads when the sun is out.
I'm thinking of using Enphase microinverters to allow for a modular system. With microinverters on each panel, could the panels be wired straight to a breaker box or would I need any other electronics in between?
I realize that power will shut off briefly every time a cloud passes. Are there any problems associated with supplying appliances and EV chargers with intermittent power? I'm worried the contactors on the EV will wear out if they are frequently switching between open and closed. Also not sure how it would affect heat pumps or other appliances.
Will there be a big voltage drop when a load is turned on? Would this cause the load to detect a power supply failure and stop charging? This is what happened when I tried to wire my 12V Dewalt tool battery charger straight to a solar panel, and the charger wouldn't give power to the batteries. I imagine without an intermediary battery the voltage will drop anytime a load is connected. Is this still the case with microinverters on each panel/is there any way around this?
I'm a college student with a few EE classes under my belt but still have a lot to learn. Any advice is much appreciated!
EDIT: Based on the responses, seems like I'll need battery storage at least for an hour or so of use to prevent voltage drop and provide steady output with clouds. I'm hoping to keep the budget under $10k for the system if possible (without including loads/appliances). If I'm using a battery, it seems like microinverters are not the way to go. What are your thoughts on running everything off a single large inverter, vs DC appliances that run directly from the battery with possibly a smaller 2-3kW inverter to power the EV charger? Also, for the size battery that I'm looking at (probably in the 3kWh range) would it be worth it to spend +/- $1000 on a root cellar to keep lithium batteries happy, or should I just go with SLA? Any recommendations for good batteries? Anyone have experience storing lithium batteries underground? Thanks so much for the help!
I'm thinking of using Enphase microinverters to allow for a modular system. With microinverters on each panel, could the panels be wired straight to a breaker box or would I need any other electronics in between?
I realize that power will shut off briefly every time a cloud passes. Are there any problems associated with supplying appliances and EV chargers with intermittent power? I'm worried the contactors on the EV will wear out if they are frequently switching between open and closed. Also not sure how it would affect heat pumps or other appliances.
Will there be a big voltage drop when a load is turned on? Would this cause the load to detect a power supply failure and stop charging? This is what happened when I tried to wire my 12V Dewalt tool battery charger straight to a solar panel, and the charger wouldn't give power to the batteries. I imagine without an intermediary battery the voltage will drop anytime a load is connected. Is this still the case with microinverters on each panel/is there any way around this?
I'm a college student with a few EE classes under my belt but still have a lot to learn. Any advice is much appreciated!
EDIT: Based on the responses, seems like I'll need battery storage at least for an hour or so of use to prevent voltage drop and provide steady output with clouds. I'm hoping to keep the budget under $10k for the system if possible (without including loads/appliances). If I'm using a battery, it seems like microinverters are not the way to go. What are your thoughts on running everything off a single large inverter, vs DC appliances that run directly from the battery with possibly a smaller 2-3kW inverter to power the EV charger? Also, for the size battery that I'm looking at (probably in the 3kWh range) would it be worth it to spend +/- $1000 on a root cellar to keep lithium batteries happy, or should I just go with SLA? Any recommendations for good batteries? Anyone have experience storing lithium batteries underground? Thanks so much for the help!
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