Report on our first grid outage and running on solar

[pvdude]

Had an “opportunity” to run the house on the inverter/batteries for the first time this morning!
The new solar we have has been operational for a couple of months now.
Grid went down @ 01:30.
We woke up and waited a few minutes to see if the grid outage was just a blip.
After 5 or 10 minutes, we received a text from the power utility to expect the power to be restored by 07:30!
Normally we would just start the Diesel generator, throw the transfer switch, and go back to bed.
But we had only briefly tested the house load, one time, on the solar batteries, just long enough to make sure it worked.
The Diesel is noisy & smoky, generally nasty to operate.
So I went through the checklist to open the breakers for big loads, before throwing the switch to put the house on batteries:

- POOL PUMPS
- DRYER
- WASHER
- DISHWASHER
- HEAT PUMP
- RANGE
- WATER HEATER


I left the well pump breaker on, so we could have water.

You can see from the graph that I was eventually able to get the load below 1kw.
When I saw the initial house load of almost 2kw, I went room to room pulling out all the power plugs for everything not essential.
That worked to reduce the load.
Was surprised at the amount of electricity used by all the small things plugged in throughout the house.
Now I need to make a better plan to disconnect all that crap w/o moving furniture @ dark o’clock.

The grid came back around 05:00, and the batteries were @ 89%.
So we are very happy, and it seems that with better load management, the house could actually run all night on the batteries.
Feeling more confident this hurricane season.

 

[12VoltInstalls]

It’s a good feeling when redundancy plans work out

 

[kenryan]

Good to see conservation is an integral part of your emergency plan (rather than brute force).

 

[MarkSolar]

You could use a zero volt release magnetic switch to drop out the loads you don't want whenever the power goes out. They're like those switches you see on large machinery or table saws, when the power goes off they drop open a magnetic switch and won't start up when the power returns unless a human pushes the button. Here's one you can buy at Home Depot to get the idea, they come packaged all different ways so they don't look so goofy in your house. I use one of these to prevent my inverter from coming back on when my backup generator starts if the grid goes down.

 

[boondox]

Oh yeah! Nice to use that system you put so much time and money into! And yeah, it is shocking how all of those little power thieves add up! Congrats!

 

[wattmatters]

Had an “opportunity” to run the house on the inverter/batteries for the first time this morning!

Nice work.

I'm yet to have a proper outage with which to test my newish set up. It will happen though, especially when Summer storm season comes.

I made the decision to be selective about which circuits would be connected to backup power rather than go through the process of opening all those circuits before cutting over. That was to help make the flip to backup as easy for my better half as possible and to idiot proof it for me. Of course one can never underestimate the ingenuity of idiots but I try.

Hence all our high power loads are not supplied on the backup side of the transfer switch, those circuits are only connected to the grid. Ducted aircon, oven, induction stove, and of course our grid solar PV tied inverter.

What this means is if the grid power returns, those items return to normal operation based on how they operate when power returns. For oven/stove, they won't come back on if they were on at time of the outage (that's a safety thing) but the ducted aircon and grid tied inverter will go back to doing whatever they were before the outage. They will operate just fine while the rest of the home is still on backup.

If we had any high power appliances going in the house then we'd turn those off. Because we are 230V supply, appliances like clothes dryers and washers, dishwashers etc all plug into regular power outlets and don't have dedicated circuits.

Our oven is our indicator grid power has returned (we have no local/outdoor indicators light neighbours or street lights to help with that). When power returns the oven clock comes on and it also makes a nice bleeping sound for a second or so giving us a nice audible and visual indication power is back. Funny thing with the oven clock. When it powers up the clock auto resets time to 00:00. But it then keeps time from that moment, so if the power returns at some stage during the night but I don't cut back over until we get up, I can read the time on the clock and know how long ago power came back on.

 

[schmism]

Was surprised at the amount of electricity used by all the small things plugged in throughout the house.
Now I need to make a better plan to disconnect all that crap w/o moving furniture @ dark o’clock.

This is what a critical loads panel is for. You can go around and prioritize circuits and depending on wiring availability converter various receptacles to critical loads panel (think red outlets around the house) This allows you to prioritize loads and not have to figure it out every time. By having a few critical receptacles handy its easy to continue to charge phones or plug in portable stuff to those few circuits understanding what the impact to the uptime would be. (carry the coffee maker over to the special outlet in the kitchen, or the toaster, or the microwave, or run an extension cord over to the TV/cable box etc)

 

[pvdude]

MarkSolar: Thanks for the magnetic switch idea, will investigate further!

wattmatters: Sounds like you have an ideal wiring configuration!
I wish I could do that, but the solar electronics are in a separate building from the house.
The way we know if the grid has come back up is to go look at the voltmeter I put on the grid conductors.

Except the “go look at it” part is not in harmony with my extreme laziness, so I pointed a webcam at the grid voltmeter……….

 

[wattmatters]

Was surprised at the amount of electricity used by all the small things plugged in throughout the house.
Now I need to make a better plan to disconnect all that crap w/o moving furniture @ dark o’clock.

This allows you to prioritize loads and not have to figure it out every time. By having a few critical receptacles handy its easy to continue to charge phones or plug in portable stuff to those few circuits understanding what the impact to the uptime would be. (carry the coffee maker over to the special outlet in the kitchen, or the toaster, or the microwave, or run an extension cord over to the TV/cable box etc)

I think a better option is to work on reducing the vampire loads to begin with. It's sucking energy and you are paying for it when perhaps much of that consumption is unnecessary. If there are appliances with large idle loads, replace them with more energy efficient units or get in the habit of turning them completely off when not in use. I guess it's easier for us as all our power outlets have switches. In the US you just plug things in and so have to pull them out of the socket to turn them completely off.

I like the flexibility of having power available at all our power outlets rather than restricting it to just a handful of outlets. Extension cords are a PITA. So while we don't have our ducted aircon at least I can plug a fan in anywhere we need it for some relief. And we can make strategic decisions about some appliances. e.g. if the outage is during the daytime then our 2.2kW off-grid solar PV is covering consumption and so we can consume more during that time if we need to without drawing on the battery.

I also have in our main hallway (and in the separate dwelling) a small plug in emergency light. It comes on automatically when power is cut providing instant light so we are not totally fumbling in the dark. Most of us have phones with lights nowadays which help but having the little emergency light activate is handy. I particularly wanted this in our separate dwelling where my elderly mum lives.

 

[wattmatters]

Except the “go look at it” part is not in harmony with my extreme laziness, so I pointed a webcam at the grid voltmeter……….

lol

 

[12VoltInstalls]

You could use a zero volt release magnetic switch to drop out the loads you don't want whenever the power goes out. They're like those switches you see on large machinery or table saws, when the power goes off they drop open a magnetic switch and won't start up when the power returns unless a human pushes the button. Here's one you can buy at Home Depot to get the idea, they come packaged all different ways so they don't look so goofy in your house. I use one of these to prevent my inverter from coming back on when my backup generator starts if the grid goes down.

View attachment 60528

Holy cow. That’s a stupid simple idea and awesome.
I can’t hardly believe in all my years of redneckery and swiss-army-knife engineering I hadn’t thought of that.

 

[wattmatters]

I use one of these to prevent my inverter from coming back on when my backup generator starts if the grid goes down.

My grid tied inverter is simply not connected to the backup side of the transfer switch (just like my ducted aircon and oven/stove are not either).

If the grid comes back on the inverter will start back up but it doesn't matter because the backup supply and circuits are all isolated by the transfer switch. The inverter can happily start producing and exporting energy and supply any loads also on the grid-only side of the switch.

This also means the grid tied inverter can never be accidentally powered on by the backup power source.

 

[MarkSolar]

My grid tied inverter is simply not connected to the backup side of the transfer switch (just like my ducted aircon and oven/stove are not either).

Our transfer switch is between the meter and the main service panel, the generator powers the whole house. There's no way to access the grid side of the transfer switch,

 

[740GLE]

That’s crazy for you idle load in the overnight, Duke must love you as a customer they’ll be sad if you start reducing your load.

 

[wattmatters]

Our transfer switch is between the meter and the main service panel, the generator powers the whole house. There's no way to access the grid side of the transfer switch,

Seems an odd placement for a transfer switch. Why is that?
Not questioning to be a pain, just curious/interested to learn.

 

[wattmatters]

That’s crazy for you idle load in the overnight

I wonder if the 2kW was normal idle consumption though, or just because something happen to start back up when power was returned but would have settled back down on its own.

We idle at ~550W but that's across 3 buildings. If I know our outage is going to be very long (days) then I can knock some of that idle consumption down. My backup system is designed be able to cope with that sort of consumption level.

So many vampire devices add up though....

 

[740GLE]

Seems an odd placement for a transfer switch. Why is that?
Not questioning to be a pain, just curious/interested to learn.

That’s normal for a whole house generator with ATS set up. No need to worry about what’s “critical load” when you have a 15-20kw genny feeding a 200a service. Feed the whole shoot and match.

Even our 7000w portable generator can run our whole house with our breaker interlock (but we have very little constant load). I just don’t use the oven or drier and hope the fridge doesn’t try and kick on same time a the well pump does.

 

[wattmatters]

That’s normal for a whole house generator with ATS set up.

Thanks.

No need to worry about what’s “critical load” when you have a 15-20kw genny feeding a 200a service. Feed the whole shoot and match.

I guess not!

 

[MarkSolar]

Seems an odd placement for a transfer switch. Why is that?
Not questioning to be a pain, just curious/interested to learn.

We actually had all the stars align when we had this generator installed. Because our main service panel is distant from our meter, there is a breaker installed as part of the meter box that exposes the main house lines out of the meter. That made it trivial to install the ATS at that point without some of the additional expense normally involved. Generac had just introduced a new 22kW generator they were promoting and it was cheaper than the 16kW model. That made it almost the same cost to put the whole house on the generator as to install a separate panel for the critical circuits. And in the final stroke of luck, the natural gas line into our house and the gas meter were too small to power the generator, but the gas company said that since our house was older than 30 years they considered the service life of the gas line to be over, so they installed a new larger line and larger meter for free. I headed straight for the racetrack that day and played the horses, I figured I'd never get luckier.

 

[wattmatters]

We actually had all the stars align when we had this generator installed.

Does the gas supply ever fail?

It's rare but once in our second most populous state there was a gas outage for 20 days after a supply point explosion.