Why "critical load panel only" when grid is down?

[cebury]

H

You can't have it be a manual switch like you are thinking

This is because of the utility back feed/isolation/islanding requirements, correct?

[inetdog]

H

This is because of the utility back feed/isolation/islanding requirements, correct?

Not entirely. The AC1 connection is configured for grid interaction so that the inverter can deliver power into the grid (either to your local loads or banking power back into the utility grid. But by design that connection can only deliver power when utility voltage is present already.
Only AC3 can deliver power when there is no grid input on AC1. That is why the connection is made from AC3 to the critical loads (needed when off grid) panel.
It is possible to run some unit in interactive mode when there is power present on AC2, but the inverter will monitor to make sure that it never tries to feed power back into the AC2 connection, since the generator could not deal with that.
When there is no power on AC1 the internal transfer switch opens isolating AC1 from AC3.

[kingofbanff]

You can't have it be a manual switch like you are thinking and to be honest you can move a lot of things to the critical load panel on your system. I would make sure you have LED bulbs in the fixtures on critical load

Well thanks for all the thoughts guys! I guess I'll keep a lot of long extension cords around the house! Then when I'm just running off solar I can plug into an outlet that is wired off my critical load panel and (assuming I'm not already using all my juice) run the cord to whatever I need to operate that isn't on the critical panel. Clearly not an elegant solution...
I'll let you know how it unfolds as we design it.

[Logan005]

Just pick your critical load circuits carefully. courtesy lighting, refrigerator, Gas appliances that require power, like oven and blower and or electro lighter for gas hot water heater and or well pump. a properly designed system will only cycle the battery bank during power fail. even if you have a full set of L-16's, it's not as much power as you think. it is only backup, If you want full house power you should consider a much larger 2 volt battery 24 of them and a "Outback flex power two" so you can maintain 240 volt appliances, but that's a lot for just backup power, you could just integrate a generator.

[ButchDeal]

Just pick your critical load circuits carefully. courtesy lighting, refrigerator, Gas appliances that require power, like oven and blower and or electro lighter for gas hot water heater and or well pump. a properly designed system will only cycle the battery bank during power fail. even if you have a full set of L-16's, it's not as much power as you think. it is only backup, If you want full house power you should consider a much larger 2 volt battery 24 of them and a "Outback flex power two" so you can maintain 240 volt appliances, but that's a lot for just backup power, you could just integrate a generator.

Good points on appliances but FlexPower 2 is a much smaller inverter system. With two radians OP is at 12kw inverter capacity, with FlexPower 2 would be limited to 7kw depending on inverters in flexpower2.

[Sunking]

ButchDeal I understand there is no way I can run all my loads but I'd rather choose what I want to run at any particular time after the grid goes down rather than before I build out my critical load panel.

Will not work and does not comply with electrical codes. No inspector would pass it. With a 48 volt 350 AH battery, the largest load it can 2000 watts. That is not much power, just enough to run a refrigerator and a few lights. In terms of ac service that is just roughly 8 amps, and no code or inspector is going to allow you to connect to a 200 amp service.This is why the Inverter manufacture built a small Automatic Transfer switch with very limited power. It forces you to install an addition breaker panel (Emergency). and reroute your selected circuits from your main breaker panel to the Emergency Panel so you cannot over load your hybrid inverter. It there to protect your equipment and most importantly your life.

IMHO you really made a big mistake using a hybrid inverter with batteries. It would have been a lot less expensive for you to install conventional grid tied system, pad mounted generator with transfer switch, and 150 to 500 gallon LPG tank. You would have exactly what you wanted. When the power goes out, generator starts and you can run anything in your home including air conditioning.

Here is the kicker, a battery hybrid system requires a generator connected to AC2 port.

[jflorey2]

Well thanks for all the thoughts guys! I guess I'll keep a lot of long extension cords around the house! Then when I'm just running off solar I can plug into an outlet that is wired off my critical load panel and (assuming I'm not already using all my juice) run the cord to whatever I need to operate that isn't on the critical panel.

No need to do that; just choose what you want to run on your critical loads panel and wire accordingly. With a Radian 8kW inverter you'll be able to operate most basic appliances/critical loads (well pumps, sump pumps, furnace blowers, fans, lights, communications) without much fuss. In addition, the Radian has a well-integrated generator input, so you can deal with longer blackouts pretty easily.

[Sunking]

the Radian has a well-integrated generator input, so you can deal with longer blackouts pretty easily.

Thus is the foolishness of a Hybrid system for a grid tied system. For equal or less money, use a conventional grid tied system with a Generator and ATS sized to run everything in the house.

[kingofbanff]

I fully understand there is a lot of energy stored in gas or natural gas which is way more efficient, however in my case for reasons I won't go into, in my situation a generator is not an option so I'm trying to do what I can with PV. thanks again for all the help.

[kingofbanff]

Here is the kicker, a battery hybrid system requires a generator connected to AC2 port.

Sunking Are you saying I have to have a generator for the Radian to work? Hmmmm, Outback hasn't mentioned that...

[DaveDE2]

kingofbanff How often does your grid power go out? Is it worth worrying about? Geez, the last time that happened here I think I fell off my dinosaur. If and when it does, good time to go for a run or take the dog for a walk till it comes back up.

[inetdog]

Sunking Are you saying I have to have a generator for the Radian to work? Hmmmm, Outback hasn't mentioned that...

You need it for when your batteries get run down during an extended outage as well as to power loads that are too large for your inverter. '
The Radian will work without a generator, but the system will not be the comprehensive backup you want and need.

[Sunking]

Sunking Are you saying I have to have a generator for the Radian to work? Hmmmm, Outback hasn't mentioned that...

Why would they want to announce that? That would likely run customers off if they knew they needed a generator. That is when the customer has an Aha moment they should use a much less expensive conventional grid tied inverter and a pad mounted generator to run everything in their home instead of suffering with minimal power and extremely expensive battery replacement every few years.

[Mike90250]

Sunking Are you saying I have to have a generator for the Radian to work? Hmmmm, Outback hasn't mentioned that...

2 reasons for a generator.
reason 1) Big storm, grid down, system switches to battery overnight, in the morning, batteries are nearly flat. and you need to heat the house via furnace. Storm means no sun for the solar, so your inverter is shutting down from low battery. MUST have a generator large enough to run Loads and Charge batteries simultaneously.
reason 2) When batteries sit low over 24 hours, they start to sulfate and that is irreversible damage to them, A generator saves your expensive battery bank.

Sizing the generator.
Wattage for loads + wattage for battery charging should come to about 60 or 70% of the rated Continuous Running load, not the misleading 5 second PEAK load.

[jflorey2]

Are you saying I have to have a generator for the Radian to work? Hmmmm, Outback hasn't mentioned that...

You don't need one as long as the grid is always there, or as long as your outages are short. But if you want to deal with long outages a generator is pretty much a requirement to keep from killing the batteries rapidly. (Note that even dedicated off-grid systems, designed for autonomy, have generators.)