Zombie Apocalypse

[SoCal Dave]

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?

 

[AEdennis]

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 run 3 PowerWall2 with my Enphase Solar, perhaps check out Enphase for batteries, they're smaller and I would think SGIP still available for folks that sell them.

Install Solar Backup Battery - Ensemble™ Technology | Enphase

 

[BrettS]

I have no direct experience with them, but I’ve seen a few videos on the Goal Zero Yeti power stations. One of the bigger units would certainly be enough to provide some backup power in the event of an extended off grid outage. I’m not sure if you could figure out a way to charge it with your existing solar panels, but people will typically get a couple of portable/foldable 100 or 200 watt panels to deploy to power the yeti during an outage.

 

[vickh]

I wish Telsa/utility would allow a bypass to the house w/o power walls. I understand grid safety but isn't there a "one-way flow" switch that can be used?

My sales guy told me a PGE horror story of having panels just sitting there while power was out for days/weeks.

 

[jboy210]

Best of luck with your plans. When I looked at this everything other than Powerwalls look very hackish in the zombie apocalypse scenario.

In fact, it was the PSPS outages (minus zombies) that pushed me to get Powerwalls. A friend mentioned how pissed he was staring up at his 15 kW solar array on 5 bright sunny outage days. He had a small generator but it was not enough to run his freezers full of meats and other supplies (he is a little bit of a prepper). On day 2 or so he tried to buy a generator. None available. So he rented the only generator available in our area. A tow-behind commercial unit with many kW of capacity. He ran cords through his house to his freezers and refrigerator. He could go into his pools, but it was starting to get a little scummy toward the end. He set up lights so he could monitor his property (never know when the zombies will attack) at night.

I am looking forward to this Fall's PSPSs. I hope I can invite my friend over for a beer. And let him sit in A/Ced comfort and watching sports on TV (which will probably be a rebroadcast of college football from the 90s).

 

[holeydonut]

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.

 

[SoCal Dave]

I wish Telsa/utility would allow a bypass to the house w/o power walls. I understand grid safety but isn't there a "one-way flow" switch that can be used?

My sales guy told me a PGE horror story of having panels just sitting there while power was out for days/weeks.

Besides grid safety, having solar systems turn off is probably a good thing for neighbors as well. Someone's solar array trying to power 5 neighborhood homes wouldn't be a good thing for anyone. There would likely be a significant voltage drop causing a brownout. Brownouts can fry motors and other equipment.

Unfortunately, the grid-tie systems don't have the capability to create the sine wave used for AC power. I've read a bit about people trying to trick the grid-tied inverter to generating power by using another inverter or a generator. However, I haven't seen clear success especially with a large system.

 

[SoCal Dave]

I run 3 PowerWall2 with my Enphase Solar, perhaps check out Enphase for batteries, they're smaller and I would think SGIP still available for folks that sell them.

Install Solar Backup Battery - Ensemble™ Technology | Enphase

Interesting. The 3kW battery is $4K. Looks like I would also need the Enpower Smart Switch which is another $2K. I'm not sure if it would work with the SolarEdge inverter to drive solar generation while the grid is down. All the documentation I've seen shows it only with their IQ 6/7's and their IQ Combiner.

 

[getakey]

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?

There is one more benefit of PWs and that is rate arbitrage. Not sure what utility you have, but PG&E is making it more and more less attractive for solar as they squeeze the Peak. PWs allow you to shift the rate structure and there is actually an ROI for the PW without an outage. Its long, but there is an ROI every day. Generators only give benefit if an outage actually occurs

 

[holeydonut]

There is one more benefit of PWs and that is rate arbitrage. Not sure what utility you have, but PG&E is making it more and more less attractive for solar as they squeeze the Peak. PWs allow you to shift the rate structure and there is actually an ROI for the PW without an outage. Its long, but there is an ROI every day. Generators only give benefit if an outage actually occurs

Agreed, after seeing how PG&E basically pays peanuts for daytime energy and then charges an obscene amount right as the sun sets; I can see a new PV-only customer having a huuuuge annual net meter deficit even if their production exactly equals their consumption without Powerwalls.

 

[jboy210]

There is one more benefit of PWs and that is rate arbitrage. Not sure what utility you have, but PG&E is making it more and more less attractive for solar as they squeeze the Peak. PWs allow you to shift the rate structure and there is actually an ROI for the PW without an outage. Its long, but there is an ROI every day. Generators only give benefit if an outage actually occurs

I find because PG&E is trying to move everyone to some sort of Time Of Use plan, I can save quite a bit of money immediately with PWs. My plan has $0.41/kWh from 4-9, $0.21 otherwise Of course 4-9 is when you come home and turn down the A/C and start really using juice. With the PWs on many days I use 0.00 kWh from PG&E. So far this has dropped my bill from around $500/mo to $70/mo.

 

[Akikiki]

@SoCal Dave, don't forget sandbags for the barricades when the Zombies start a-walkin'. I'm saving up to head the same thing you are.

 

[gpez]

I have no direct experience with them, but I’ve seen a few videos on the Goal Zero Yeti power stations. One of the bigger units would certainly be enough to provide some backup power in the event of an extended off grid outage. I’m not sure if you could figure out a way to charge it with your existing solar panels, but people will typically get a couple of portable/foldable 100 or 200 watt panels to deploy to power the yeti during an outage.

I was going to suggest the Yeti as it does PV tie and provides backup power. Have no experience myself, just one of the options I looked at when going through the exact same exercise as you, @SoCal Dave. Powerwall ended up winning.

Yeti 3000 Lithium Portable Power Station w/ WiFi Control | Goal Zero

EDIT: Now after looking I noticed that the Yeti only does 12v panels, doesn't integrate with grid tie PV

 

[SoCal Dave]

There is one more benefit of PWs and that is rate arbitrage. Not sure what utility you have, but PG&E is making it more and more less attractive for solar as they squeeze the Peak. PWs allow you to shift the rate structure and there is actually an ROI for the PW without an outage. Its long, but there is an ROI every day. Generators only give benefit if an outage actually occurs

I'm with SCE. With my back of the napkin estimates, I believe we will be fine with the TOU w/o Powerwalls. Our system is over sized and we can shift our usage out of peak especially if we do the TOUD-5-8PM plan.

Once our PTO kicks in, I'm switching our ACs to cool the house very comfortably during the day and then switch off at 5 PM.Usually by then it is starting to get comfortable where we don't need the AC or our insulation will carry the temperature for a while. I'm also going to make sure the pool equipment doesn't run during this time and possibly will turn off one of our pumps for our ponds.

 

[holeydonut]

I'm with SCE. With my back of the napkin estimates, I believe we will be fine with the TOU w/o Powerwalls. Our system is over sized and we can shift our usage out of peak especially if we do the TOUD-5-8PM plan.

Once our PTO kicks in, I'm switching our ACs to cool the house very comfortably during the day and then switch off at 5 PM.Usually by then it is starting to get comfortable where we don't need the AC or our insulation will carry the temperature for a while. I'm also going to make sure the pool equipment doesn't run during this time and possibly will turn off one of our pumps for our ponds.

How are you going to convince people not to cook dinner, do the laundry, or crank them ACs?

 

[SoCal Dave]

How are you going to convince people not to cook dinner, do the laundry, or crank them ACs?

We have a gas stove and oven, so my wife can cook me all the dinner she wants Our dryer is also gas as well.

I just installed Wifi thermostats so they are easy to program. My wife is actually looking forward to having the AC run cooler during the day and then shutoff at 5 PM. I believe I can actually lock out the physical thermostats and control them from my phone if anyone starts to cheat.

AC, pool and ponds are our major electrical usage.

 

[getakey]

you guys are not so hot
forecast this week is 109 high, 78 low

 

[SoCal Dave]

you guys are not so hot
forecast this week is 109 high, 78 low

The 78 degrees as a low is painful - no relief at night. For me this weekend we are supposed to hit a high of 105 and a low of 72.

 

[getakey]

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

 

[jboy210]

We have a gas stove and oven, so my wife can cook me all the dinner she wants Our dryer is also gas as well.

I just installed Wifi thermostats so they are easy to program. My wife is actually looking forward to having the AC run cooler during the day and then shutoff at 5 PM. I believe I can actually lock out the physical thermostats and control them from my phone if anyone starts to cheat.

AC, pool and ponds are our major electrical usage.

Pre-cooling is a good id

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

And people ask me why I don't live in the Central Valley any more!!

We get to the high 90s maybe 100, but it goes into the 60s at night