# How do you prioritize circuits in a renewables home?



## Bobbb (Jan 7, 2012)

Let's say that you have a freezer, or two, full of meat. If your power goes down for a few days, then the contents of those freezers are at risk of spoilage.

If you have a form of on-site power generation how can your prioritize the distribution of that power to specific circuits in your home? I'm not talking about hooking a generator up and plugging your freezers in, rather a solar or wind system which is a permanent fixture.

Let's say priority #1 in the event of grid power failure is to direct the electricity to the freezers. Then priority #2 is to direct the left-over power to the kitchen range. Then priority #3 is to take whatever power remains and direct it towards the lighting in the living room. Then priority #4 is . . . . 

How would you wire a new house to implement such a priority sequencing? Multiple fuse boxes with very small circuit loops? Anyway to do this without making the walls a rat's nest of wiring and without physically having to manage the rationing process by unplugging devices from the circuits?


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## cowboyhermit (Nov 10, 2012)

Without a complex monitoring system it is tough, one option that is relatively simple is to instal low voltage disconnects (preferably adjustable) on non-essential loads, it can get complicated depending on the setup and whether loads are inverter powered or dc.


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## Jerry D Young (Jan 28, 2009)

One way is to set up the breaker panel where it is easy to get to and just turn off the power to the individual circuits where you don't want power on at some point, while continuing to feed those circuits you do want hot.

Very similar is to split the feed into two, three, or four sub-panels through appropriate sized breakers. Have the various levels of circuits go to separate breaker boxes. Then, rather than turning on and off many different circuits, you can just flip the sub-panel feed breakers in the main breaker box to shut of all the circuits in that set of branch circuits.

To add automatic, or remote switching will be very expensive, with a moderately complicated power management program to operate it. 

Although... By adding high power relays between the main breaker box and each of the sub-panels, you could have a bank of simple low voltage on/off switches somewhere handy to open the relay, rather than going to the breaker box and flipping the breakers manually. 

I do think the sub-panels are the way to go, with or without the remote switching.

Just my opinion.


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## Caribou (Aug 18, 2012)

My first priority would be to reduce the need for electricity. Covering the freezer(s) with blankets for added insulation should give us a couple extra days at least. Contents of two freezers could be combined into one. Some items might be placed in the fridge to help cool it then canned when they thawed. I would unplug any unnecessary vampire loads. If it is cold enough outside the freezer contents or the entire freezer might be moved outside. 

My priorities are not likely to be fixed. In the winter my priority is likely to be my heating system. When the solar gain is adequate or the oven is on the heating system could take a lower priority. If the batteries are near full that may be a good time to run the freezer for an hour or two. I would anticipate a constant weighing of expected energy production Vs. possible usages. 

One four watt LED per person will provide adequate light so the batteries would have to be really low before I worried about lowering the priority of the lights.


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## Bobbb (Jan 7, 2012)

I'm trying to get my head around a system which doesn't need human oversight in order to function, for the most critical elements at least. 

Say that you're away from your home for a few days or a week doing whatever it is that needs doing in a world gone to hell. Meanwhile you've stored a season's worth of meat in a freezer. While away your grid power goes down for a week because the massive riots sweeping the country have taken out a critical distribution center. Now your home's renewable system is all you've got. There's no one there to pull the plug on the clock radio and the TV and the computer and all other gadgets which create phantom loads and besides maybe the system you've got can't fully duplicate the power input provided by the grid.

I wondering if there are computer controllers which, when tied in with a home-based power generation facility, can prioritize the circuits on your fuse box?

I suppose you could wire the house with two systems - the first is to your solar and that power ALWAYS powers your critical items, like freezers, and the second system is your grid system which powers everything else. There would likely have to be a crossover of some kind so that the grid could help out your solar power system if there is a call for it. Anyone have thoughts about this aspect.

I appreciate the advice about manually taking care of business but how would you go about it so that it's wired into the house. Jerry's remarks are along the line that I'm thinking of.


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## Jerry D Young (Jan 28, 2009)

I added a drawing, including the remote relays. Interfacing a control system to them in parallel or instead of the individual switches should be fairly easy. 

If nothing else, the primary could be normally on, and the other three relays normally off, so when commercial power went out and the relays defaulted to unpowered state, the feed to the primary circuits would fail to on, and the others would fail to off, cutting off power to everything except those items on the primary circuits.

Just an idea.


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## mosquitomountainman (Jan 25, 2010)

If you just want an emergency generating system that will be used for a week or less in a grid down situation I'd advise going with a standby generator large enough to power the entire home. 

A standby generator is a permanently mounted unit that will be turned on automatically if the grid goes down. When the power goes out a transfer switch disconnects the home from grid power and automatically starts your generator. Most units are propane powered but other - less desirable - options are available. Hook one up to a large propane tank and it will run for weeks without supervision. 

Forget the tiered system you're contemplating. If it's powered by solar or wind you cannot rely on a steady power supply which would be essential for this type of use. All the tricked up wiring and switches you'll need are recipe for disaster.

An alternate idea might be a grid-tie solar power system with battery and generator back-up. Then add a transfer switch to turn on the generator when the battery bank falls below a specified level and turn it off when the batteries are charged.

Just out of curiosity, why not just wire the emergency system to send power to the fridge and freezers only then give yourself the capability to manually shunt power to the range (electric range = bad idea if you're on solar!), lights, boom box, etc.?

None of these things will be needed unless someone is home anyway.


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## Bobbb (Jan 7, 2012)

mosquitomountainman said:


> If you just want an emergency generating system that will be used for a week or less in a grid down situation I'd advise going with a standby generator large enough to power the entire home.


I'd prefer to avoid a fossil-fueled generator just for emergencies. I'd like to rely on a system which is working all the time.



> Forget the tiered system you're contemplating. If it's powered by solar or wind you cannot rely on a steady power supply which would be essential for this type of use. All the tricked up wiring and switches you'll need are recipe for disaster.


There would be battery storage, not just a direct feed from the panel/turbine.

The switching shouldn't, in principle, be a recipe for disaster. These home electrical components are pretty solid in terms of reliability.

I can't count on reliable solar or wind, especially to power an entire household, but with the triage approach I'm focused on, I'm of the opinion that I can have a supplemental system, with batteries, which powers a portion of my electrical needs but when push comes to shove and the critical elements need their power then this system will have to provide all of the power until normality returns.

A generator is good insurance but I won't be using it unless I need to. A supplemental solar/wind system would be functioning all the time.

The reason I got on this line of thought is the flooding in Alberta. If I have a hydro system, one of the most dependable of the home-based renewables, I'll still have seasonal variation in water flow (the solution to which is to design capacity for minimum flow) but if a disaster like that which struck Alberta comes my way, that small hydro system will be severely damaged or destroyed by a massive flood. Same with grid power. Same with a tornado taking out solar panels or a wind turbine.

If I can build some redundancy into the system then it's less likely that events will wipe out each of the systems. So a small solar+batteries system which contributes a small share of the power needed by the house but isn't critical during normal times fits in with that scenario. It just has to be sized appropriately to power the critical items in the household.



> Just out of curiosity, why not just wire the emergency system to send power to the fridge and freezers only then give yourself the capability to manually shunt power to the range (electric range = bad idea if you're on solar!), lights, boom box, etc.?


That's what I had in mind but maybe I wasn't clear in my writing. I don't need to power the range if the house is empty, but those freezers need to keep functioning. When someone is in the house then we can fine tune how the power is distributed. If though I can automate much of that through switching or controllers, then I'd be interested in seeing how to accomplish that goal.


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## Marcus (May 13, 2012)

Why not just run your renewable power to just the freezers with manual breakers for the rest of the household?
You could use an automatic AC battery charger on a timer (turns on at night) to keep the batteries in your renewable power system fully charged.

You keep the breakers to the freezers turned off at the main panel until you need to use your renewable power system in the rest of the house.
All you'd need to do is install a breaker box for just the 2 freezers so you can turn off the renewable power to the freezers when you wish to use the power elsewhere.
In a grid down situation, you'll want to turn off the main breaker so your renewable power isn't fed back into the grid when you using the power elsewhere in your house.


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## cnsper (Sep 20, 2012)

Rather than prioritizing the power usage, design the system to support a full load from your household for several days. You might also want to look into DC freezers and refers as they will not have the same power loss that you get from converting to AC. You can also do what the Amish do and have propane refers and freezers.


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## Bobbb (Jan 7, 2012)

cnsper said:


> Rather than prioritizing the power usage, design the system to support a full load from your household for several days.


This strikes me as an inefficient, brute-force, approach. It's going to cost a lot more to have a independent system which is fully capable of powering the entire household than it will to have a partial system which is capable of powering only the critical elements.



> You might also want to look into DC freezers and refers as they will not have the same power loss that you get from converting to AC.


Good point.



> You can also do what the Amish do and have propane refers and freezers.


If society goes down the toilet, where does one get propane refills?


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## BillM (Dec 29, 2010)

Power everything you intend to run and duty cycle individual devices with timers.

For instance freezers could by powered for an hour every three hours and would run during those times as needed. 

Most lighting could by cycled off during daylight hours.

Electronic devices , such as radios and TV could be shut off except for hours when they would be in use.


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## mosquitomountainman (Jan 25, 2010)

What most of us who live off the grid do is use less electricity on the low power days (days with little sun or wind) and more when the power production is good. If you have enough home-grown power to run your essentials in an emergency situation why not just wire them in permanently and keep them off the grid entirely? Then you can shunt power to the non-essentials as you have it.

After living off-grid for the last ten (plus) years I have little confidence in solar or wind power in bad-climate situations. The same weather calamities like flooding, tornadoes, ice storms, etc. are also the worst situations for solar and wind generation. We have two back-up generators for the time they're needed but we've also evolved to the point of very seldom needing them.

That, IMO, is the key to self-sufficiency. Don't be dependent upon "modern" technology. It's all too interdependent on too many other systems. It's like the difference between a Model A Ford and 2013 Cadillac. You can keep a Model A running with baling wire. The best defense against the things you're talking about is less dependence upon freezers and other "non-essentials." Plus the more pieces a system has, the more prone it is to failure.

Anyway, keep us posted on your progress. I'd like to see how you resolve the issues.

Steve


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## zimmy (Aug 17, 2012)

*re home system*

This is one of the ways I do it. This is a double pole double throw 200 amp transfer switch. When the power goes out I just start the generator and throw the switch which separates the utility from the house, no brain power required.

Keep in mind that the generator input can be replaced with something else like a renewable energy system. This was purchased from Harbor Freight 6 years ago with a 20% off coupon.


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## GrinnanBarrett (Aug 31, 2012)

I believe you are referring to a Transfer Switch. If you plan to hook your generator directly to the house you really need to use a Transfer Switch. Otherwise, you can electrocute a worker trying to work on the lines around your neighborhood. The transfer switch is installed next to your regular fuse box and powers only a few outlets and stays within the power output of the generator you are using. The Generator is hooked directly to the transfer switch. 

What is a transfer switch?
A transfer switch is an electrical device that is installed next to your electrical panel in your home. It connects to the circuits in your electrical panel that you wish to power during an electrical outage.

This allows you to power these circuits by connecting the generator to the transfer switch, instead of having to run extension cords to various items.

Why do I need a transfer switch?
A transfer switch is required by the National Electric Code for any connection of power to a home.

A transfer switch is the only safe way to directly connect the generator to your home.
A transfer switch isolates selected circuits your home from the power lines. This prevents back-feed, which occurs when power goes back down the utility lines.
Back-feed can not only damage the generator, but has the potential to cause a fire.
Even worse, back-feed could electrocute any technicians who are working on the lines - causing injury or even death.
A transfer switch eliminates the risk of back-feed. It is the only safe way to connect your generator directly to your home.

A transfer switch is the easiest way to power your home during an outage.
Running extension cords to and from appliances can be awkward and time consuming. A transfer switch lets you use your home's wiring system to power any appliance in your home with your generator quickly and easily.
Other items like a furnace or a well pump cannot be connected to a generator with an extension cord. A transfer switch is the easiest and safest way to connect these items to the generator.

A transfer switch can increase the usefulness of your generator.
A transfer switch makes power management very easy to do. You can easily turn on and off various circuits to accommodate changing power needs.
This helps you to use a smaller, less expensive generator to meet your power needs. It lets you use your generator more efficiently - with less effort on your part.
Our Universal Transfer Switch, for example, can increase the usefulness of your generator, making it behave like a model as much as 20% larger.



How does a transfer switch work?
A licensed electrician will install the transfer switch into your home and connect it with the main breaker box.

The main breaker in the transfer switch switches the power source from utility to generator. The house cannot be connected to both the generator and utility power at the same time - the main breaker transfers power from one source to the other.

This prevents the generator power from back-feeding through the utility lines, as well as preventing utility power from back-feeding into the generator.

The transfer switch also contains a number of circuits. You can instruct the electrician to assign each circuit to a different load. For example, you might want to power the furnace, well pump, refrigerator, and some lights. You can assign different circuits to power each appliance or room.

You may have more items on different circuits than the generator is capable of powering at the same time. However, using a transfer switch will make it easy to switch between different loads. Just turn one circuit off, and the other on. Our Universal Transfer Switch will even do this for you. A transfer switch makes it easy to manage your power usage and maximize your generator's effectiveness.

What options are available?


Honda has a wide variety of transfer switches available to meet many different needs. Talk with your dealer to help you make the right selection for your needs.

Manual models
These are very simple switches. You manually turn circuits on and off to manage the load on the generator and prevent overloads. Manual switches are typically less expensive because of lower installation costs.

A variety of models and styles are available, including models that can be expanded up to 16 circuits.


Automatic (Universal) Transfer Switch
The UTS, or Universal Transfer Switch, is an integral part of Honda Portable Power Systems (HP2S). It automatically handles many of your power needs during an outage.

The UTS is highly programmable. You can determine which items have the highest priority. It will automatically adjust the generator's power flow as necessary to prevent overloading the generator. There is no need to manually toggle circuits or switches.

The UTS makes power management easy - increasing how many items you can power with your generator.

The UTS also monitors the status of your utility power. When power is restored, it automatically reconnects your home to utility source and disconnects it from the generator.


The UTS is also configured to use with a UPS (Uninterruptible Power Source), a battery backup. A UPS can provide temporary back up power for immediate needs before starting your generator. For example, you might use the UPS to power your garage door, a few lights, or your computer to check the weather forecast.

Additional information about the UTS and Honda's HP2S

Inlet Box
For many generator applications, you'll want to install an inlet box on the outside of your home.

How do I use a transfer switch?
Manual Switches:
Your owner's manual will have detailed instructions on using your transfer switch properly. Be sure to review it thoroughly before use.

When the utility power goes out:
Connect the generator cord to the transfer switch or inlet box.
Turn off all the circuit breakers in the transfer switch to the off position.
Start the generator and let it warm up.
Flip the main breakers in the transfer switch to the Generator position.
Turn on the circuits you wish to power, one at a time. This will help to prevent the generator from being overloaded.
When the power is restored:
Turn the main breakers in the transfer switch back to Utility Power.
Turn on any other circuits that were turned off.
Turn off the generator.
Disconnect any cords.
UTS:
Simply start your generator and connect it to the transfer switch. The UTS will automatically detect power and adjust the circuits as necessary. When power is restored, disconnect your generator and turn it off.

Be sure to review your owner's manual thoroughly before use.


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## zimmy (Aug 17, 2012)

*R.E. Home system*

My second system is a standalone Trace inverter that will power critical systems like freezers, refrigerators, and propane heater control circuits while I'm away.

My third system is a 8kw grid tie system.

My fourth system is a propane backup heater set lower than the other heating systems and will come on if I am away.

I have baseboard elec heat, propane heat, wood boiler heat, mini split heat pump, battery bank, low voltage PV array, high voltage PV array, grid tie inverter, stand alone inverter, diesel generator, gasoline generator, hot water heat pump, solar hot water sys, electric hot water tank. A backup, for a backup, for a backup. You can do the same.


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## smaj100 (Oct 17, 2012)

Bobb,

One of the latest things i've been playing with for other projects as a hobby, is an Arduino. This is a small circuit board with a baby computer chip if you will, these can be used for an unlimited amount of home automation. The link I included below is an arduino being used to turn on a light. These can be had for a very small price and your imagination is the limit as to what you can tell them to do. You could easily put a temp sensor on a circuit inside the freezer and when it falls below a certain point turn on a relay allowing it to power up, or use a timer with some very basic code.

I've built a complete weather station from scratch with remote control capability and it reports the data over a wireless tx into my house which stores it on a unit that reports to the network where I can call the information up on any device in my house, cell, tablet or laptop. Just another thought.


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## helicopter5472 (Feb 25, 2013)

EMP, all these will be destroyed. Be nice to design a complete system EMP proof. Hard to do since most items in home all have circuitry EMP pulse would destroy.


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## zimmy (Aug 17, 2012)

Not so fast helicopter5472, I have 4 layers of foil faced insulation board on the outside and in attic of my house. I also have window quilt blinds with foil faced Mylar between the layers of quilting. I have attached a pic of the insulation board, I would have to search through my file pics to find the blind photos.

It is almost impossible to make or receive a cell phone call from within the house.


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## helicopter5472 (Feb 25, 2013)

zimmy said:


> Not so fast helicopter5472, I have 4 layers of foil faced insulation board on the outside and in attic of my house. I also have window quilt blinds with foil faced Mylar between the layers of quilting. I have attached a pic of the insulation board, I would have to search through my file pics to find the blind photos.
> 
> It is almost impossible to make or receive a cell phone call from within the house.


I don't know enough about EMP, so probably I'm blowing smoke, but you are still hooked up to the utility, and use inverter/batt as a backup. But from my understand being hooked up to utility it will still surge thru your system, (like what happened way back when, they had telegraph lines catch fire and burn) even though your house may be covered. It seems only items that are not connected to any power source in your protected home (grounded cage) would survive. What about thru the windows that aren't covered. No one knows if and when this type of terror/natural act may accure, so you may be away from home at the time and not be able to disconnect from the utility.


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## zimmy (Aug 17, 2012)

Helicopter5472. Yes I see what you mean, well at least I tried.


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## LincTex (Apr 1, 2011)

It's all speculation at this point anyway.

I wonder if the thickness (or actually, thinness) of the foil lined insulation would be enough protection. I would think steel or aluminum siding of some sort would offer more protection. Still... speculation.

I hope to someday have our fridge and chest freezer on their own U.P.S. They can get grid power when needed, and run off of batteries until the system can be attended to. I never took into account the occurrence happening when away for an extended period of time (more than a day). If the SHTF while traveling out of the area, I don't think my fridge/freezer will be a very high concern.


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