Prepper wannabe - solar powered freezer

[Metalophile]

Hi all, I'm fairly new around here, but I have had a small off-grid 12v lead acid battery system fed with 150 watts of panels and an MPPT charge controller for off-grid backup power for years. Mainly it is there to run my ham radios and for some power to have in case of emergencies and grid failure. I live in a suburban area, and I want to be prepared in case of a grid-down situation - either from solar flare, grid hacking, or EMP scenario. One of the gaps in our prep plan is food storage. We have a lot of frozen grass-fed beef (expensive) in chest freezers in the garage near the front of the house. But my best panel area is a sunny spot in the back yard, about 80 ft. from the garage. Wife is dead set against moving the freezers to the back patio closer to the solar panels. I have plans of expanding my ground mounted panels in the back to about 600 watts, but then I move and expand my batteries from the patio at the back to about 3kWhr of LiFePO4 into the garage so the battery pack(s), MPPT, and inverter would be there close to the freezer(s). I live in the mid-South of the country, so it definitely gets below freezing at times in the winter. I had planned to keep the LiFePO4 in the garage where it doesn't drop below freezing. However, that's a long run of wire from panels to the MPPT - 80ft. Now, I'm having concerns about running 10AWG solar wires from the back yard, through the attic to my garage. I calculate that long of a run with a panel voltage of ~28V will cost me a few percent of power. If a code enforcement officer sees that he might object to that - and if I have 600w of panels it will pretty much be visible from an adjacent street. Also, having my solar system in the garage which is attached to the house - does that raise any safety concerns? So before I drop a couple of kilobucks on this project, I wanted to bounce this project idea off of this forum - especially the safety aspects. Am I overlooking some easier way of powering one or two chest freezers off grid? Maybe build a shed for my solar system and the freezers in my sunny spot?? Also, I have thought about getting a conventional grid-tie system with 5-7 KW of panels on the roof. Not sure I would want to do both systems simultaneously, but the grid-tie system doesn't do anything to solve our solar powered freezer storage goal - unless I have the installers add a couple of extra panels for my off grid subsystem - does anyone do that - and would code enforcement object to that?

 

[boondox]

Code issues are dependent on local, so you need to ask some local folks in the construction/power business.

Most grid tie systems don't give you power if the power goes out. You can get one that does but often not the "we put up the panels and you save money" type of companies, at least around here.

Moving the power is easily done if you go with AC, 80 feet is no problem. You can do it with DC too, just bigger wire. The one real bottom line is that the panels have to be in the sunniest spot. Everything after that is a question of proper design. 80' is not an insurmountable problem.

 

[Metalophile]

I'm just now learning about the Bluetti AC200. It looks like that unit would almost meet my needs, except a) it is a bit under the capacity I was shooting for at 1.7 kWh vs ~3 kWh, b) the Bluetti FAQ says it can't be used like a UPS - (which would have been a nice feature until I get all my solar up), c) external battery capacity can't be added (although there is a provision for car charging - maybe another 12v battery bank could be attached to that charging port??). d) Does anyone know if the Bluetti's are UL listed? I haven't found that information yet. That would calm some of my safety fears, although the fact that they don't use LiFePO4 does raise my concern on safety. An all-in-one product like the Bluetti would be nice because I would trust my wife and kids to be able to run it, but it would take extensive training for them to fiddle with a DIY system like I was planning. Also, it would be a nice item to have in a bug-out situation. Grab and go. The 2000 W output would also be useful in a power outage to run a microwave oven or small hot plate for emergency cooking.

 

[sremick]

Iit is a bit under the capacity I was shooting for at 1.7 kWh vs ~3 kWh

This is the reason I finally gave up on the off-the-shelf options and decided to build myself another. 13.44 KWh in a portable unit.

 

[Metalophile]

This is the reason I finally gave up on the off-the-shelf options and decided to build myself another. 13.44 KWh in a portable unit.

I hope you have that on wheels! Yes, the more I think about it with all the components crammed into one box if one component in the Bluetti blows out, you're up a creek. With DIY, you just buy another module, charge controller, inverter, or BMS. Expand capacity as needed. I'll have a stationary system, but I do have some long extension cords to bring the AC power where I would need it. I think had I learned about the Bluetti a few days ago I would have gotten one at the pre-pre-price, but I think I'll pass at this point. Hey, one other crazy idea I had was to convert a golf cart to LiFePO4, and the golf cart becomes my solar system storage and emergency power center when not in use as a vehicle. My city has approved golf carts to be used on all city streets.

 

[Metalophile]

I also need to decide whether to go big and 24V or stick to 12V. If I go big I can find 1kw of used panels for about $400 locally, go with a 45-50A MPPT, and DIY a 24V-280AH LiFePO4 battery pack for about 7kWh, 24v 2000w inverter. Then I could easily power both of my garage freezers and have battery capacity to spare. If I go smaller that means sticking with 350w of panels I currently already own (and possibly needing to add to those), still need the same amperage MPPT charge controller, and a 12.5v-280AH LiFePO4 pack to DIY for 3.5 kWh and 12V 2000w inverter. That would then power only one freezer. Does anyone know of any halfway decent ~2000 watt pure sine inverters that are configurable between 12/24v? If I could find a dual voltage inverter I could more easily start with a 12v system, then convert to 24v later.

 

[sremick]

I hope you have that on wheels!

It'll probably come in at about or under 50 lbs which isn't bad. My existing SLA battery weighs almost 49 lbs and that's only 900Wh. I thought about rigging up wheels and a pull-out handle like with luggage but I usually have one of those collapsable wagons with me when I'm camping or festival-ing so it's probably an unneeded/redundant additional hassle/complication.

 

[mckennab]

It'll probably come in at about or under 50 lbs which isn't bad. My existing SLA battery weighs almost 49 lbs and that's only 900Wh. I thought about rigging up wheels and a pull-out handle like with luggage but I usually have one of those collapsable wagons with me when I'm camping or festival-ing so it's probably an unneeded/redundant additional hassle/complication.

Just to be clear you're talking about a 3KWh system coming in at under 50lbs, not your 13.44KWh behemoth right?

 

[sremick]

Just to be clear you're talking about a 3KWh system coming in at under 50lbs, not your 13.44KWh behemoth right?

Where the frack did I get that math? Yup, I botched that pretty badly. And I can't edit, so I am forced to submit to humiliation for eternity. :D

3.36KWh

 

[Freep]

A Carrington event or EMP that would take the grid down would also destroy your equipment. You'd need to set up a system, power it down, disconnect it, put each component in EMP protective bags then put all of that in a faraday cage and then hope they would still survive the event.

Your best bet is to use an old school propane freezer with no electronics and have a big propane tank that you routinely top off. You can run a freezer for years with a large whole house propane tank.

 

[Metalophile]

A Carrington event or EMP that would take the grid down would also destroy your equipment. You'd need to set up a system, power it down, disconnect it, put each component in EMP protective bags then put all of that in a faraday cage and then hope they would still survive the event.

Your best bet is to use an old school propane freezer with no electronics and have a big propane tank that you routinely top off. You can run a freezer for years with a large whole house propane tank.

Hopefully with a Carrington type solar flare we would have a day or two warning, then I would have time to disconnect and store the electronics. However you're right, for an EMP attack. Would have to keep spares in a Faraday cage.