Zombie Apocalypse

[mspohr]

Normally, power in my area is very stable - only 2 outages over a few minutes in 10 years. However, now that I have my grid-tie system installed, I'm thinking about what I could do if there was ever a big emergency and grid power was unavailable for days or weeks. In this scenario, I'm looking at a few hours of minimal power a day. Run the freezer for a few hours, run chargers, and other minor emergency usage. AC, pool/pond pumps and other heavy equipment would go silent.

Tesla Powerwalls are the easy solution, but to me would be way too costly. With my 12.24kW system, Tesla recommends 3 Powerwalls for $23K (pre-incentive). It doesn't look like Tesla would let me get a singe Powerwall, but even if they did they would still want $11K (pre-incentive).

A small generator seems like a reasonable and probably most realistic option. Home Depot has some for less than $300. I don't like the need for gasoline, mechanical parts, and my expensive solar array would be sitting silent. But it is cheap and easy.

Portable Generators - Generators - The Home Depot

I have 3 strings going to my 10kW SolarEdge Inverter. For $900, I could potentially buy a 3kW Sunny Boy and have a string run to this inverter. This would give me their Secure Power Supply Outlet while the panels are generating electricity. No gas or moving parts. It also gives a bit of redundancy if I lose one of the inverters.

SMA Sunny Boy 3000W Inverter SB3.0-1SP-US-41 | Webo Solar

Are there any Powerwall like alternatives? Something relatively small and inexpensive which would allow my array to run off-grid if needed? Or anything else I might want to consider?

I have installed an Outback Power Skybox. It's about $4K. 5kW output. Accepts Solar PV strings, generator and batteries. Works with microinverters. It will use any kind of batteries (or even no batteries). Since I too only have rare power outages, I've installed AGM lead batteries for the rare outage. The 5 kW will cover essential power needs (refrigerator, lights, etc.)

I also have a SMA Sunny Boy inverter on one string and the Secure Power Supply Outlet works well as long as the sun shines.

 

[SoCal Dave]

I have installed an Outback Power Skybox. It's about $4K. 5kW output. Accepts Solar PV strings, generator and batteries. Works with microinverters. It will use any kind of batteries (or even no batteries). Since I too only have rare power outages, I've installed AGM lead batteries for the rare outage. The 5 kW will cover essential power needs (refrigerator, lights, etc.)

I also have a SMA Sunny Boy inverter on one string and the Secure Power Supply Outlet works well as long as the sun shines.

Thanks for sharing. The Skybox looks very interesting.

 

[SoCal Dave]

8 straight days of 100 or more. Have reduced 109 to 107
starting Thursday:
100
105
107
105
104
105
102
100
lows range from 72 to 78

Wow, stay cool! This would be me:

 

[jboy210]

There's only 5 more months left of 2020; please no zombies. Remember when Australia and the the rain forests being on fire was our headline news? I miss those days.

We can all move to New Zealand. They are freaking out because one family of 4 had Covid. 1st cases in 100+ days.

I love the place and would be happy to spend the rest of 2020 there. But since I have a US passport I am screwed.

 

[MorrisonHiker]

I just want to point out that gas doesn't last forever and would be difficult to obtain oil and refine it during a zombie apocalypse. While Powerwalls won't last forever either, they would remain viable longer than oil-derived fuels. Other fuels such as ethanol could be used but would require a large amount of land that might be better used for food production.

Solar panels themselves can work for decades.

It would be much easier to locate, set up and maintain solar panels, batteries and inverters if a zombie apocalypse occurs.

 

[woferry]

There's only 5 more months left of 2020; please no zombies. Remember when Australia and the the rain forests being on fire was our headline news? I miss those days.

We can all move to New Zealand. They are freaking out because one family of 4 had Covid. 1st cases in 100+ days.

I love the place and would be happy to spend the rest of 2020 there. But since I have a US passport I am screwed.

Heh. I got super-lucky in both regards. Was on a 2 week AU/NZ cruise last week of February/first week of March (my first time in either country). So just cleared most of the AU fires, and got to see NZ before things shut down. The next sailing of the cruise (reverse route back to AU) got cancelled mid-cruise as the whole industry shut down. So a week later would have been an entirely different story. Though at least I was on a line that has always taken cleanliness seriously, so I felt safer on the boat than returning to the US.

 

[holeydonut]

I just want to point out that gas doesn't last forever and would be difficult to obtain oil and refine it during a zombie apocalypse. While Powerwalls won't last forever either, they would remain viable longer than oil-derived fuels.

Solar panels themselves can work for decades.

It would be much easier to locate, set up and maintain solar panels, batteries and inverters if a zombie apocalypse occurs.

Can't you just capture a zombie and put them on a big hamster wheel generator? Free Energy! Perpetual motion machine...

 

[MorrisonHiker]

Can't you just capture a zombie and put them on a big hamster wheel generator? Free Energy! Perpetual motion machine...

Good question! I think you're onto something there!

 

[jboy210]

Heh. I got super-lucky in both regards. Was on a 2 week AU/NZ cruise last week of February/first week of March (my first time in either country). So just cleared most of the AU fires, and got to see NZ before things shut down. The next sailing of the cruise (reverse route back to AU) got cancelled mid-cruise as the whole industry shut down. So a week later would have been an entirely different story. Though at least I was on a line that has always taken cleanliness seriously, so I felt safer on the boat than returning to the US.

Wow. Sounds like you dodge a bullet. Although, if you had to be stranded somewhere I can think of worse places than Australia or New Zealand. Did you get to that island where they had the volcano eruption?

We were in New Zealand for 2 weeks because my wife and daughter are huge Lord of the Ring fans. We went to both islands to see where they shot various scenes and spent a couple of days at the Hobbiton movie set.

Very nice people, and a beautiful country.

 

[SoCal Dave]

I just want to point out that gas doesn't last forever and would be difficult to obtain oil and refine it during a zombie apocalypse. While Powerwalls won't last forever either, they would remain viable longer than oil-derived fuels. Other fuels such as ethanol could be used but would require a large amount of land that might be better used for food production.

Solar panels themselves can work for decades.

It would be much easier to locate, set up and maintain solar panels, batteries and inverters if a zombie apocalypse occurs.

I hope it is understood I'm not actually worried about a Zombie Apocalypse

The Outback Power Skybox msphor suggested is looking really appealing. At $3,328 (pre-incentives), it would let me run 5kW of my solar panels while there is sun out. I can then add battery in incremental investments if I wanted to. For me, this seems like a more appropriate direction than having to plunk down the cash for 3 Powerwalls upfront.

 

[gpez]

I hope it is understood I'm not actually worried about a Zombie Apocalypse

The Outback Power Skybox msphor suggested is looking really appealing. At $3,328 (pre-incentives), it would let me run 5kW of my solar panels while there is sun out. I can then add battery in incremental investments if I wanted to. For me, this seems like a more appropriate direction than having to plunk down the cash for 3 Powerwalls upfront.

Skybox is not a bad option if you're looking for emergency only power.

That said with 12.24kWof PV you likely could do 2 PWs - Tesla may recommend 3 but their guidance allows for 2. Further, if you're OK operating your PV at half capacity during an outage you could get away with 1 PW and simply place half of the PV on the other (grid) side of the Powerwall. It's only a bit more expensive than the Skybox but comes with batteries.

I went through the same calculus you did and ended up getting 8.55kW of PV and just Powerwall only for backup. I'll be good during bad weather, an earthquake, zombies, whatever. Extremely happy with it.

 

[SoCal Dave]

Skybox is not a bad option if you're looking for emergency only power.

That said with 12.24kWof PV you likely could do 2 PWs - Tesla may recommend 3 but their guidance allows for 2. Further, if you're OK operating your PV at half capacity during an outage you could get away with 1 PW and simply place half of the PV on the other (grid) side of the Powerwall. It's only a bit more expensive than the Skybox but comes with batteries.

I went through the same calculus you did and ended up getting 8.55kW of PV and just Powerwall only for backup. I'll be good during bad weather, an earthquake, zombies, whatever. Extremely happy with it.

Tesla's website is saying 1 Powerwall is $11K though. I'm thinking $3.3K for the Skybox and maybe 1kWh of batteries initially. Then increase the batteries over time.

 

[getakey]

I think you would be much better off going with PWs even though more expensive especially if you add to the Skybox later

 

[gpez]

Tesla's website is saying 1 Powerwall is $11K though. I'm thinking $3.3K for the Skybox and maybe 1kWh of batteries initially. Then increase the batteries over time.

View attachment 575552

Bleh, forgot about the TEG price. Was just referring to the Powerwall's ~80% price premium but has batteries. You'll still need to do some install for the Skybox, though I'm sure it's a bit more DIY-able than a Powerwall.

Of course it just comes down to the math for you!

 

[mspohr]

Tesla's website is saying 1 Powerwall is $11K though. I'm thinking $3.3K for the Skybox and maybe 1kWh of batteries initially. Then increase the batteries over time.

View attachment 575552

I installed 8 x 100 ah SLA AGM batteries on my Skybox. About $1300 for 9.6 kWh of capacity (about 7.5 kWh usable). This is plenty of capacity to get me through the night and recharge the next day from my PV string.
This is for emergency use so I expect very few cycles each year so the lead batteries should last a long time. I'm also not trying to run everything, just essential loads.

The Skybox is very flexible. 5 kW output. If you want more capacity, you can stack up to 8 Skybox units for 40 kW output. You can also use any type of battery... just set the parameters in the Skybox. Generator input could come in handy if you have one. Generator input will charge the batteries as well as run loads up to 10 kW.

 

[SoCal Dave]

You'll still need to do some install for the Skybox, though I'm sure it's a bit more DIY-able than a Powerwall.

Yah, it actually looks like a fun project for me to hookup.

I wonder what Tesla would do if 1/3rd of my power stopped producing because I was going through a different inverter. I assume they would give me issues with any warranty repair work as well.

 

[mspohr]

Yah, it actually looks like a fun project for me to hookup.

I wonder what Tesla would do if 1/3rd of my power stopped producing because I was going through a different inverter. I assume they would give me issues with any warranty repair work as well.

I did a DIY install of my Skybox. It was easy. Just wired to grid, load, PV string. Batteries were the most work but I bought a large diameter wire kit and a good crimper.

 

[SoCal Dave]

I did a DIY install of my Skybox. It was easy. Just wired to grid, load, PV string. Batteries were the most work but I bought a large diameter wire kit and a good crimper.

I assume you have Tesla panels? Any issue with warranty support?

 

[mspohr]

I assume you have Tesla panels? Any issue with warranty support?

No Tesla solar so I don't know how they would react to rewiring the system.
I have four set of panels. Two strings and two sets of microinverters. I've wired one of the strings (4.4 kW, 12 panels) to the Skybox inverter. Only my first set of panels (microinverters) was done by a professional installer. That was 6 years ago. Never needed any service.

 

[JeremyWhaling]

One thing to note on using your existing solar with a different inverter - you have optimizers on each panel, and without a solar edge inverter to talk to, I don't think they'll let power flow (open strings just show 1V/panel).