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What is your power backup plan?


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After watching David's latest video on his backup power solution, I'm seriously interested in building a system like this of my own. 

My house is already solarized, and I'm just waiting for final inspection and the operating permit. However, having the ability to run off-grid is still interesting to me, and I'm considering some of the same things David did: installing a 4-circuit transfer switch and a large lithium pack to run off-grid indefinitely, provided enough solar power is available.

The power station, AC, and transfer switch are the items (as near as I can tell) David used in his video. The solar panels are not; David bought used panels from a local retailer

Does David's backup and energy saving plan give you any ideas? What would you do differently? 

 

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I had solar installed about 4 years ago, but it is all on grid. It makes my electric bill effectively zero, because I generate as much or more than I use. The biggest problem (and it isn't often a problem) is when there is a power outage, because then I can't use the electricity that my panels generate (if during daylight hours, anyway). I'd like to install a battery backup at some point so that I have it when and if I need it.

One thing I rationalized is our RV as part of an emergency preparedness plan. It has some on board battery capacity, a gas generator, and propane, so if our house were to be uninhabitable in some way, we have the RV as a backup living space with the comforts of home, at least for a small period of time.

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Before COVID, I had all the Marriott points I could ever want, and that was my plan. Since my business travel has completely stopped, I used up all my points for personal use. What definitely helps is that I moved from a place with frequent power outages (easily one every two weeks) to one with very few (just one very brief -- less than 2 minutes --- outage over the last 8 months).

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I have had a few multi-day outages, the longest being 5 days after Snowtober in 2011.  After that I added a gas-powered portable.  Setting it up was a nuisance, but it was better than nothing.  Until the day I needed it and the carb float valve was stuck. Gas everywhere...

Now I have a natural gas powered whole-house standby generator.  It's been great but we've only had brief outages since installing it a couple of years ago.  I considered solar + powerwall, but that won't cut the mustard if I end up powerless for a week with a foot of snow on the roof.

I also have a small place in rural Maine that houses an elderly family member.  Outages are frequent and automation is a must (it's a 3-hour drive in good weather).  There I have a similar standby generator, powered by propane.

Both installations are overkill, but I can be away and not worry about either house.

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On 6/1/2022 at 2:01 PM, Scott Robison said:

I had solar installed about 4 years ago, but it is all on grid. It makes my electric bill effectively zero, because I generate as much or more than I use. The biggest problem (and it isn't often a problem) is when there is a power outage, because then I can't use the electricity that my panels generate (if during daylight hours, anyway). I'd like to install a battery backup at some point so that I have it when and if I need it.

One thing I rationalized is our RV as part of an emergency preparedness plan. It has some on board battery capacity, a gas generator, and propane, so if our house were to be uninhabitable in some way, we have the RV as a backup living space with the comforts of home, at least for a small period of time.

I've been thinking more about how to use one of those battery units in conjunction with a generator and/or solar system. David's setup has me thinking I could run the generator for 2 hours or so to charge up the battery, then let that run my equipment most of the day. So then I'm not wasting fuel by basically idling the generator when not using it. 

I may get a few extra panels specifically to charge the battery unit, and use that for backup power when the grid is down. I just put up solar, too, and I bought enough solar power (8.5KW) to offset my bill. But I'm still considering adding another 2.4KW through the AC2000MAX to add another extra bit of off-grid functionality. If I can offset an extra 1-2KW by moving my gear over to off-grid solar power, then we can earn that money back by going further negative with our net metering... considering the cost of electricity here, the 2000MAX and 2KW of solar would pay for itself in about 3 years. 

Now I find myself wishing I'd gone with a slightly smaller install, so I could spend the $3000 it would take to replicate David's setup.

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On 6/1/2022 at 4:42 PM, TomXP411 said:

I've been thinking more about how to use one of those battery units in conjunction with a generator and/or solar system. David's setup has me thinking I could run the generator for 2 hours or so to charge up the battery, then let that run my equipment most of the day. So then I'm not wasting fuel by basically idling the generator when not using it. 

We have a 1000 wh battery that my wife uses when we're in the RV to run her CPAP, which we charge from our home AC as needed. What I'd really like to get is a something comparable to a power wall so that I have lots of emergency power, but for now that's more than I want to spend.

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On 6/1/2022 at 4:01 PM, Scott Robison said:

The biggest problem (and it isn't often a problem) is when there is a power outage, because then I can't use the electricity that my panels generate (if during daylight hours, anyway).

How much would it cost just to add an automatic transfer (or isolation) switch? Not a full battery setup.

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On 6/2/2022 at 8:39 AM, kelli217 said:

How much would it cost just to add an automatic transfer (or isolation) switch? Not a full battery setup.

It isn't something I've investigated so I can't say. I should contact the contractor that put in the system originally and see if it is possible.

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On 6/2/2022 at 7:39 AM, kelli217 said:

How much would it cost just to add an automatic transfer (or isolation) switch? Not a full battery setup.

Unfortunately, It's not as simple as just installing a transfer switch.

Solar uses a grid tie inverter to convert the panels' DC power to AC power and synchronize it with the utility company power. Grid tie inverters aren't meant to be a primary power supply and won't work when there's no power coming into the house. Since solar power is very variable, you need the grid to act as a sink for the excess power and a supply when the solar power isn't enough for your demand. So you still need a battery system or a 4KW+ generator to provide a source of 240V power that the solar inverter can sync up with. That's part of what PowerWall (or a similar system) does: it provides a power sink to allow you to use your solar off-grid.

That, of course, requires an automated transfer switch, which is a bit more expensive than the manual one that David demonstrated.

 

 

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On 6/1/2022 at 12:57 PM, TomXP411 said:

What would you do differently? 

I live on Vancouver island, a location fought with wind storms knocking out power, tsunami potential, earthquake risks and forest fires too. We rarely see any thunderstorms or tornadoes, and rarely a heat wave or snow storm. Anyway disaster prep is rather big here; I'm not prepared and I know it.That being said I've joined my town's emergency communication radio volunteer group - are HAM licences and use of a portable radio. If a disaster hits hopefully I get a shelter bed & food for volunteering - I will get a emergency role.

Anyway three items that I though of that might influence how you prepare for the next disaster:

- Candles are discouraged as they now present a fire hazard. I still am going to have some, but both my wife and I grew up with using them. We aren't expecting heat or significant light from them, just more of and emotional comfort item (which has it's own value.)


- Dishes. A fiend went through a power outage for a couple of days. He had a BBQ and camping stove. He found the bulk of the fuel was used to heat water for washing dishes. He recommends paper plates for his emergency kit - they can be garbaged/burned and save on fuel and time. He also suggest a couple of those evil plastic utensils that probably are in our kitchen drawer for that someday use that hasn't come. the hopefully would be washed and recycled after the disaster.

- See what your government has to help you be informed for the next issue - https://www2.gov.bc.ca/gov/content/family-social-supports/seniors/health-safety/emergency-and-disaster-preparedness If you have the will consider volunteering in your local community, the benefits are great.

 

 

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Posted (edited)

Mine is not all that impressive, but it works for me.

I have a few 30,800mAh battery packs, a portable "camping" 204Wh power station with a built in solar maintainer/charger, and a 1000VA UPS here at home on the modem and router for the most common short outages. I also have a rather large stock of AAA/AA batteries on hand for projects, radios, and flashlights.

That's enough to power our "portable entertainment" devices quiet a long time. Plus, we have plenty of board and card games on hand. lol

If I am desperate, I do have two power inverters I can take down and plug into my car to charge up devices.

Living in northern Wisconsin, I don't often need much in terms of AC, but for long periods with no power for heat, I have a nice kerosene heater and enough fuel on hand for several days of running. Though you really don't have to run it much, this place holds heat well, so it would likely last a couple weeks.

In all reality, the longest outage we have had here in 18 years was about 14 hours, and I slept through most of it. 😛

 

What would I do differently? If I really needed them...

1. I would like to buy a couple nice solar panels for long-term charging of devices like phones, tablets, and portable battery packs.

2. Find the largest 5V, 9V, or 12V LCD display for running the a Pi3 or Pi4 off battery for as long as possible, purely for entertainment. The lower the power draw the better obviously.

3. Invest in a small, but good, gas generator.

 

Edited by Strider
Added what I would do differently.
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Mine is basically my electric car with a external 1kWh power station which I connect to the DC/DC converter which charges the internal 12V battery. I can connect this up to one circuit in our apartment (additional breaker to disconnect from the grid). That's the one where the fridge is connected, plus some other sockets. Of course we would have to re-connect stuff to those other sockets. Then we also have a one-plate electrical stove for cooking, which only draws 1kW max - the power station allows up to 1.2kW. Then we have a small 500W room heater, just in case.

The car is usually charged to 60kWh which should last at least for 20 days for the fridge, lights, basic appliances and some cooking. If we have to heat a room, then it might be 5 days.

I'd like to put up solar, but because of regulations (condo building) that's not going to happen.

In Switzerland it's been well over 20 years in our region since we had a unplanned power-outage. And even the planned ones... (construction work etc) I think that's been 10 years. So I basically prepared for the unthinkable, but because of the war in Ukraine, now you never know...

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On 6/3/2022 at 1:05 AM, AndyMt said:

The car is usually charged to 60kWh which should last at least for 20 days for the fridge, lights, basic appliances and some cooking.

While I think you might be optimistic about your run time, especially with inverter losses, I do think EV batteries are a good choice for a secondary backup. I talked with my solar guys about that, and "two way inverters" (the thing you need to do it legally here in the US) are still not commonly available. The Ford F-150 Lightning can do it, but none of the other EVs that have bi-directional charging can actually power a house, yet.

I am a little curious about the "additional breaker to disconnect from the grid"... how do you have this set up? Here that would mean yet an additional sub-panel with a transfer switch in it, along with permits and potentially a permit from the power company to operate.

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On 6/3/2022 at 6:21 PM, TomXP411 said:

While I think you might be optimistic about your run time, especially with inverter losses

Maybe. We use approx. 6kWh during a day right now. That's excluding the car, but including the washing machine, dishwasher, home cinema, cooking, baking, home office everything else etc. I estimate that when we don't use dishwasher, washing machine, dryer etc. that we come down to half of that. We are only a 2 person household, the apartment is 100 m2, our fridge only has 60l capacity (basically everything is smaller than in the US 😉).

On 6/3/2022 at 6:21 PM, TomXP411 said:

I am a little curious about the "additional breaker to disconnect from the grid"... how do you have this set up? Here that would mean yet an additional sub-panel with a transfer switch in it, along with permits and potentially a permit from the power company to operate.

We have a panel in each apartment and there is reserve space to add such things. Regulations requires that, so that you don't run out of space immediately. 

I'm not a certified electrician, but my father is... so he took care of the power company and the permits, I helped with the installation. So basically I have an additional 3-phase breaker (actually it's a switch, you are right) in the panel now (everything is 3 phase in Switzerland). This means I can only power one phase from the car, but that's totally fine for an emergency situation (kitchen and living room are on the one I chose).

The connection is done via a so-called "blue plug" (usually used for RVs and boats) in the garage. The power company doesn't care that much where the power comes from, it could be a gas-generator or in my case an inverter/powerstation.

I've tried it once, to see if everything works and it's fine. It's not an automatic setup, far from that. I have to dismount the back bench of the car, to get to the DC/DC converter connectors and hook up the power station. The station then is recharged by the car, while the stations inverter provides power. I've tested connecting an inverter directly, which worked, too. But I'm worried about drawing such a high load over the DC/DC converter directly. So the power station acts as a safety buffer. Of course losses will add up, so you are right, probably it's more like 14 days, considering that. But I think that's quite cool.

If I just had some PV to recharge...

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  • 4 months later...

Some points..

 * Use 48 V DC for batteries, solar panels, etc. It needs a lot thinner cables and waste a lot less power. Power loss = Cable resistance * (Current)^2

 * 48 V DC is also not mandated by law to be installed by an electrician in some jurisdictions. Falls under IEC definition of ELV. NEC term "LDSV".

 * 48 V DC will make conversion to 120 or 230 V AC a lot less messy.

 * Put combustion power and heat machinery in a separate building and then pipe heat and electricity back to the living area. Avoids the CO issue.

 * There are battery chemistries like NiFe which can be refurbished by yourself and other interesting chemistries like those based on sodium-nickel, easy access chemicals but requires 245 - 350 °C.

 * Put volatile batteries like Lithium based ones inside a ceramic or concrete containment with a smoke exhaust should they fail.

 * It's not rocket science to build converters from DC to AC. Power IGBT, controllers, phase adjustment and back EMF are the keys.

 * Every electrical car contains enough electrical storage capacity to handle the mains power needs. And it comes with builtin charger and a Variable-Frequency-Drive. If you can control the frequency and amplitude of the later you have your (backup) mains power.

 

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I've now improved my setup further, because I've found a solution for solar for our condo apartment:

6x200w solar panels on the terrace:

image.thumb.png.9a6e64e22895a81a25c81fe78fce865b.png image.thumb.png.de671872676d2db6484cb5c9491217d0.png

 

These are feeding into an Ecoflow Delta Max with 2kWh of battery capacity.

My office is connected to the EcoFlow and running entirely off that (including a 3d printer). In case of emergency I can switch over so I can power the entire apartment with up to 2.4kW of load. If it's getting really desparate then I can connect a 2nd inverter to my electric car, which will provide 60-70 kWh of capacity (I keep it above 80% charged all the time). As described above this would be enough to run the apartment for at least a week if we reduce our consumption. And if the sun is shining just 4 hours a day, the Ecoflow is fully charged again. Charging the car is technically possible, but would take weeks and means to restrict power use in the apartment down to almost 0.

Is this setup cheap? No!

Does it pay off anytime soon? No! (maybe after 20 years)

But it is a lot of fun to see how we produce our own energy now. We've run the apartment with this setup on sun and battery for 3 days in a row. Of course that required to not use the dish washer, dryer or washing machine. The stove we've used briefly of course, also the coffee machine, but not the oven. But in a longer emergency situation, we can wash dishes by hand, clothes should be in stock for a week or two.

Using the Ecoflow gives me all the control and data stats via WLAN I need. You can get the same for half the price if you build everything yourself, but I just wanted to have it working right away. And for the first time in 20 years, last week we did have an un-anounced power outage. This demonstrated that the setup works very well. But it also showed that indeed as expected there is no internet when there is no power. Mobile networks were fine though.

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On 10/22/2022 at 11:47 AM, AndyMt said:

Does it pay off anytime soon? No! (maybe after 20 years)

Better to see it as an insurance policy. They have to be payed in advance not after the "house has burned down" and may never "pay out" if everything is alright. Just having light to take care of medical emergencies, cooking after sunset, finding the toilet seat, being able to wash hands etc improves circumstances a lot. It can also power communication and entertainment. All small power loads which makes a huge difference for the energy expended.

Expect mobile networks to work for a few hours at most. Their design criteria is to provide power long enough for a service technician to visit and fix the power problem. If it's really important a mobile diesel-generator will be put in place by the cell operator or the state. If you want to be ensured communication HAM is the answer.

Btw, are those solar panels secured in case of windy conditions?

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On 10/23/2022 at 1:56 AM, neutrino said:

Btw, are those solar panels secured in case of windy conditions?

Yes - they are held in place with 3mm thick steel wires attached to the sockets of the hand rail.

On 10/23/2022 at 1:56 AM, neutrino said:

Better to see it as an insurance policy

Indeed, that's how I see it, too. For heating, I'm not too worried as the apartment was built to passive house standards. I just need to make sure the ventilation can run for an hour, to exchange the air. Even with no clear sky and sunshine these houses heat up by themselves because they are so well insulated. And we get well below freezing temperatures here in Switzerland during Winter.

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