Batteries For Home Standby Power

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kwired said:
They would all want to come over to the one place that has light, heat, etc.:happyyes:

If lead acid batteries and they vent anything it will be hydrogen gas - possibly something to be more concerned about then having a few gallons of gasoline stored somewhere on the premises.

Maybe the condo needs to look into some sort of generator to supply the entire place. Don't know how to make the cost fair to everyone, as not everyone necessarily uses even amounts of energy when it is needed.
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If they are flooded lead acid (FLA) batteries, I would be much more concerned about the acid mist that is vented regularly when the batteries are gassing during charging than the hydrogen/oxygen gas mixture.
 
gadfly56 said:
The OP's customer lives in a condo. "No solar panels for you."
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While it can be an obstacle, there is nothing about living in a condo per se that prohibits solar panels. There's actually a law now in California that prevents condo HOAs from having blanket prohibitions. Don't know about Massachusettes though...
 
mkgrady said:
Is it a given that lithium ion batteries would be the right choice?
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FLA or SLA batteries don't like it when you draw them down very far. Even marine rated FLA's for deep cycle shouldn't go below about 50% or so. LiO batteries, like the Tesla Powerwall 2 can go pretty much to empty without issue (nominal 14 kW-hr, available 13.5 kW-hr).
 
jaggedben said:
While it can be an obstacle, there is nothing about living in a condo per se that prohibits solar panels.
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Not specifically, but in many multi story condominium buildings, no single tenant owns any part of the roof.
 
dont batt the whole place.
fridge, some lights, washer, TV cable box & tv (for news & Netflix while power is out), etc.

is the whole place electric? or is the dryer, stove, and water heater gas?
 
When we have residential customers who want a solar system designed to carry their entire load the first thing we insist on is a comprehensive energy audit of their home and then sit down with them to figure out ways to both reduce their demand and even more importantly, their expectations of what their new system can or will feasibly do when they find themselves temporarily off grid. If it's just a couple days they can get by with a few kWh worth of portable battery power. If it's the zombie apocalypse they're probably gonna bail on that condo anyway.


mkgrady said:
I have a customer that asked for a quote for a standby generator for his townhouse condo. I gave him the quote for a 16kw unit. It was going to power his entire load with load shedding relays on the electric oven, dryer and AC. Now he says he does not think the condo board will approve a standby because of the noise during exercising or running during an outage. He is suggesting a battery and an inverter.

My response without any real experience with batteries powering a home is that it would be expensive. He wants me to look into it and I am willing. If nothing comes of it I should still learn something. He has plenty of room in his unfinished basement for batteries.

He is willing to forget about powering all that a 16kw standby could handle. He listed all the critical things that we can all imagine....gas burner for heat system, refrigerator, tv, WiFi, microwave, a few
Lights, etc.. I explained that some of these loads are connected to circuits that supply other than the critical stuff and the system would have to be large enough to power whatever is connected or plugged in.

I’m looking for some feedback on how practical this concept is. I would assume the system would need about 5kw peak load and have an average output of 2kw. These numbers are just shooting from the hip. If these numbers are anywhere near close, how big of a battery would I need to survive a power outage for four days?

My gut tells me the battery bank would be enormous, the inverter battery charger would cost a fortune and I’m not sure what the transfer equipment would be. Anybody have opinions on this?
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FionaZuppa said:
dont batt the whole place.
fridge, some lights, washer, TV cable box & tv (for news & Netflix while power is out), etc.

is the whole place electric? or is the dryer, stove, and water heater gas?
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Yes that is the plan (post #1) to just run the essential circuits but I figure that will often be about 2KW and short burst of up to 5KW for when the fridge kicks on while the microwave is running and someone starts a toaster.

Heat is gas, Electric dryer, Oven and AC but I would not power any of those things from the battery
 
mkgrady said:
Yes that is the plan (post #1) to just run the essential circuits but I figure that will often be about 2KW and short burst of up to 5KW for when the fridge kicks on while the microwave is running and someone starts a toaster.

Heat is gas, Electric dryer, Oven and AC but I would not power any of those things from the battery
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You can get away with a much smaller than 5 KW inverter or inverters if the customer understands the limitations of it... That is not running the microwave and toaster at the same time.

Customer would be better off buying a small dorm fridge for essentials, and buying a lower wattage microwave...those two items will probably cost about 250 bucks, which is about the cost of one good AGM deep cycle battery. Also, they should get a two slice toaster oven instead of a four or six that they probably have.... or only toast two pieces of bread at once

They must absolutely do everything they can to pare down their power usage, otherwise it will cost a small fortune in batteries to run those loads for 4 days. If they have a porch or terrace, you could put solar panels on a rolling cart of sorts. I would also be inclined to make the battery/solar setup a standalone system not tied into the condos electrical system, and just use extension cords to power the desired loads.
 
Redwood Infrared said:
When we have residential customers who want a solar system designed to carry their entire load the first thing we insist on is a comprehensive energy audit of their home and then sit down with them to figure out ways to both reduce their demand and even more importantly, their expectations of what their new system can or will feasibly do when they find themselves temporarily off grid. If it's just a couple days they can get by with a few kWh worth of portable battery power. If it's the zombie apocalypse they're probably gonna bail on that condo anyway.
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Not to belabor the point, but the OP's client lives in a condo. He doesn't have access to the roof, which is likely the responsibility of the association. Most condos you only own to the depth of the sheet rock on your interior walls. To repeat, "No solar for you."
 
gadfly56 said:
Not to belabor the point, but the OP's client lives in a condo. He doesn't have access to the roof, which is likely the responsibility of the association. Most condos you only own to the depth of the sheet rock on your interior walls. To repeat, "No solar for you."
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Not to belabor the point, but see post 23.
 
jaggedben said:
Not to belabor the point, but see post 23.
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  1. The OP is in MA not CA
  2. The client WILL NOT own access to the roof. That's just the way condo associations work. He also doesn't own the exterior walls, for that matter.
  3. Suppose the client is one of three occupants, one on each floor. Who would have access to the roof now?
 
gadfly56 said:
  1. The OP is in MA not CA
  2. The client WILL NOT own access to the roof. That's just the way condo associations work. He also doesn't own the exterior walls, for that matter.
  3. Suppose the client is one of three occupants, one on each floor. Who would have access to the roof now?
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The client is a member of the HOA and can propose an easement or such. There is no law against an HOA allowing an installation that everyone agrees on.
This IS done. I've installed such systems. I've also seen some projects get cancelled because the client couldn't work things out with the HOA.
You're talking as if you know all the details of the clients situation, and you don't.
 
jaggedben said:
The client is a member of the HOA and can propose an easement or such. There is no law against an HOA allowing an installation that everyone agrees on.
This IS done. I've installed such systems. I've also seen some projects get cancelled because the client couldn't work things out with the HOA.
You're talking as if you know all the details of the clients situation, and you don't.
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The one thing we DO know is that that the client isn't considering solar. Access to the roof or lack thereof is really off target.
 
JFletcher said:
You can get away with a much smaller than 5 KW inverter or inverters if the customer understands the limitations of it... That is not running the microwave and toaster at the same time.

Customer would be better off buying a small dorm fridge for essentials, and buying a lower wattage microwave...those two items will probably cost about 250 bucks, which is about the cost of one good AGM deep cycle battery. Also, they should get a two slice toaster oven instead of a four or six that they probably have.... or only toast two pieces of bread at once

They must absolutely do everything they can to pare down their power usage, otherwise it will cost a small fortune in batteries to run those loads for 4 days. If they have a porch or terrace, you could put solar panels on a rolling cart of sorts. I would also be inclined to make the battery/solar setup a standalone system not tied into the condos electrical system, and just use extension cords to power the desired loads.
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By a large margin the biggest consideration is air conditioning.
 
ggunn said:
By a large margin the biggest consideration is air conditioning.
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That's true enough. It's very likely that the A/C will be on it's own circuit, possibly (likely?) 2-pole, and easily separable from the other loads. Might be trickier if the hot water is electric as well. Heat will still need electric for thermostat and blower, if not also the igniter. Fundamentally, it's still going to be $6,000 per 13.5 kW-hr of load. Pick and choose accordingly.
 
gadfly56 said:
That's true enough. It's very likely that the A/C will be on it's own circuit, possibly (likely?) 2-pole, and easily separable from the other loads. Might be trickier if the hot water is electric as well. Heat will still need electric for thermostat and blower, if not also the igniter. Fundamentally, it's still going to be $6,000 per 13.5 kW-hr of load. Pick and choose accordingly.
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My original description put the capacity at about 200 KWH. Average of 2KW for four days. That comes to about 88 grand based on the above calculation. I don’t believe he would spend half of that. Maybe I should tell him we can only power the fridge and the gas heater and tell him to use flashlights. I have no idea how to calculate the average load for a fridge and a gas heat system over four days but suspect I’m probably looking for an inverter to put out 1KW with a peak output of 3KW in order to start the motors associated with each. Am I even close?
 
mkgrady said:
My original description put the capacity at about 200 KWH. Average of 2KW for four days. That comes to about 88 grand based on the above calculation. I don’t believe he would spend half of that. Maybe I should tell him we can only power the fridge and the gas heater and tell him to use flashlights. I have no idea how to calculate the average load for a fridge and a gas heat system over four days but suspect I’m probably looking for an inverter to put out 1KW with a peak output of 3KW in order to start the motors associated with each. Am I even close?
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I think your 200 kW-hr for 4 days is far too conservative, especially for a condo, unless there is electric hot water heating. My 1,600 sq ft home in July, with the A/C basically going non-stop, averages 30-40 kW-hr per day. Drop the A/C and that would go way down.

I'd say see how many Powerwalls he's willing to buy and see how much load you can support, less A/C, for 4 days and see if that gets him a solution he can live with.
 
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