Small Cabin Prototype System

[timeforagorism]

This is my first system. As you can probably tell it was modeled after Will's videos and links. It was easy to recognize Will as a ‘trusted source’. I definitely don’t mind contributing to that 50K a month affiliate linkage ?

The final goal of whatever system I come up with will be to handle a 360 sq ft cabin. The cabin will be super insulated with a solid air barrier. Matt Risinger, and David Poz’s content has given me many things to consider.

Loads:

• Power tools
• Maybe a base board electric heater for evenings. With the small space, super-efficient building techniques, and passive day heating this may do.
• Maybe a pellet stove. These seem to pull 70watts continuous and 400w for the ignitor.
• Lights
• On demand water pump
• Freezer
• Converted stand up freezer to fridge
• CPAP
• All the other things I haven’t calculated load for yet.

This is my current prototype I have been running for about 6 months now. Now that we are in winter I have definitely learned about the effects of shading and the amount of sun hours on solar production.

Current load:

• Stand up Freezer – 400 watt hours daily
• Converted Stand up freezer to fridge – 400 watt hours daily
• 8W Led lights

The panels are Canadian Solar 315W. They have a 39.9 VOC and it rarely gets below 10 degrees F here. After running it through a bunch of calculators it seemed like 3 in series would be fine even in winter. They currently show at about 111 volts on the charge controller.





The fortune cells were really nice to work with as someone being brand new to DIY batteries. Especially during the top balance process as the lugs are so beefy. The Overkill solar BMS are great because I can monitor each pack during cycles. Although Will’s latest video has me wanting to buy the Victron monitor that is 130 now, the other 200 dollar one was hard to justify.



Loads I am running on the prototype daily:





Things I still need to do:

• Ground the array
• Ground the inverter and do more research on this. I need to learn more about grounding is the moral of that story.
• Figure out how to build compression boxes for the Lishen 272AH cells I just bought.
• Double or triple this array at the cabin
• Find a suitable inverter, charger, or some combination of those.
• Stalk these forums more

PS - Hopefully I removed the metadata from my pictures. I just read a thread on here reminding me to do that. Cheers to the group on that one. And a sneak peak of the cabin since I did mention it.

 

[MichaelK]

Nice cabin. I could make some suggestions for your to-do list.

Things I still need to do:

• Ground the array (build a ground mount array like the one I have pictured below. It's sunk in concrete, so is automatically grounded.)
• Ground the inverter and do more research on this. I need to learn more about grounding is the moral of that story. (Drive an 8' ground rod into the earth along side the cabin. At HomeDepot they cost 12$.)
• Figure out how to build compression boxes for the Lishen 272AH cells I just bought.
• Double or triple this array at the cabin (The ground array I have in the pic could hold 6 grid-tie panels in a "landscape" orientation. You could wire them in a 3S2P configuration.)
• Find a suitable inverter, charger, or some combination of those. (With six of your panels you could be producing 60+ amps at 24V, so you'll need a controller that can handle 60+amps. I'm partial to Midnight, and I have three Midnight 200 controllers. I would also recommend Schneider's Conext 4024 inverter. It can produce both 120/240V split-phase AC, and can be coupled to a 120/240V generator to charge the batteries. I think it's perfect for my workshop, where I'm powering all my tools.)

I would advise against solar baseboard heat. Not a good use of solar resources. Personally, I would install a traditional woodstove instead of pellet. Wood is something I produce myself off of my own land. I would consider propane for periodic heat instead of the baseboard. It could be fed with either 20# or 100# tanks. If you expect the interior of the cabin to get cold in winter, lead-acid batteries might be a better choice. Lead-acid can still function far below freezing. I feel that a self-heating Li battery system is just a problem waiting to happen.

 

[Steve_S]

Too bad you did not provide a link to that ground mount.
Seems like that one can be adjustable ?

 

[timeforagorism]

Yea, I have been toying with the idea of a super insulated box to hold the batteries. I have read that you can do this with just small electric blanket. I just setup a small pet electric blanket on a meter to see how much it uses over 24 hours. It is jumping all over the map .5, 7w, 9,w, 20w, 40w, etc.

 

[MichaelK]

Too bad you did not provide a link to that ground mount.
Seems like that one can be adjustable ?

There is no link. If you thought is was commercial, then thank you very much! I made it out of welded unistruts, and schedule 40 pipe. It's adjustable both seasonally, and also rotates left to right for manual solar tracking. I usually post this pic in case anyone wants to copy this design. BTW, I am especially proud of the cantilevered trusses supporting the back. They go over the hinge to allow for the seasonal adjustments.

 

[MichaelK]

Here are also some pics of my first-generation rotating arrays. I designed this to hold three 72 cell 300W grid-tie panels. They also adjust both seasonally and over the course of the day. I simply go out and rotate them by hand. My primary goal is running my 240VAC well-pump. By tracking east to west, I can produce 2000+W to run the pump from 8am till 4pm.