Your House’s Electrical System and Catching Up

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So, on Monday, May 1, this is what it looked like outside my front door at 5 AM.

Yes, that’s snow. Nice weather we get here. This is why I haven’t been talking about gardening and bicycling and drone flying and putting up photos of pretty flowers and all that stuff. We had two or three days of summer like weather in March with temperatures in the 80s, and ever since then it’s been like this… cold, wet, cloudly, and now snow. Welcome to Wisconsin. Sigh… The weather has since gotten a bit better. It’s still been so cloudy with occasional rain that we’ve been making pretty much zero solar power. Again, sigh… Of course I shouldn’t complain. I have a friend who lives about 100 miles north of here in the upper peninsula of Michigan and over last week or so he got 52 inches of snow.

What I wanted to talk about is that someone asked why I need two inverters bolted to the wall and not just one. Just one of those inverters can supply 6.5 KW of power, as much as my big Generac gasoline generator, and enough to run almost the entire house as long as we’re careful. So why do I need two of them?

Partly it’s a question of capacity. 6.5 KW is a bit close to the edge for us, so to speak, at least as far as normal daily life is concerned. We may complain about our electric bill but we do like appliances like our coffee makers, our convection oven, etc. With just one inverter there would be times we would be pushing over that 6.5 KW limit. Two inverters give us a comfortable cushion.

The biggest reason though is that we also need 240V power to run some of the appliances in the house. For that we need both inverters. Initially I’m not going to be hooking any 240 appliances into this system because I don’t have eno0ugh batteries and solar panels to handle it, but eventually that’s going to change so I wanted a system that could be switched over easily in the future.

WTF is 240V split phase?

The average person doesn’t know, and doesn’t need to know, what actually goes on in the electrical system of the house. As long as your toaster or computer or TV works when it’s plugged into the wall and the lights turn on when the switch is flipped, that’s all they care about. And for most people that’s fine. But if you want to switch your home to an alternative energy system you need to know what’s going on behind the scenes.

While most of the systems in your house run on 120 VAC, in all likelihood there are some that require more power than a normal 120V line can supply. Things like electric water heaters, clothes dryers, electric stoves, well pumps, etc. will often run on 240V, not 120. The amount of power these appliances require would overload the normal 120V wiring systems in the house. So let me explain what’s going on without this getting complicated.

Well it’s going to get complicated anyway but let’s see what I can do.

What you have coming into your house is two, 120V AC power lines, not one. The two lines can be combined inside your circuit breaker panel to give you 240V to power more power hungry appliances like HVAC systems and clothes dryers.

If you took the front panel off of the main circuit breaker panel in your house it would looks something like the one in the photo below.

Now you’ll notice a couple of things right away if you look at that photo up there carefully. Note that there are two rows of circuit breakers, not one. There is a reason for that and I’ll come to that in a minute.

The next thing I want you to look at is right at the top center of that picture. You’ll see three thick wires coming in from the top. One is black, the 2nd is marked with red tape, and the third runs off to the right of center and is marked with white. Those three lines are what comes in from the service panel attached to the outside of your house and which, in turn, is fed from the utility company. The black wire and the red are the two 120V lines coming into the house and the white is the neutral line.

In your panel are two metal strips called busbars that the two hot wires (sometimes called legs because why not) connect to. Each busbar runs the length of the panel. The circuit breakers in the panel connect to those busbars to get the power that they then send out to the wires that lead to the outlets, lights, etc. in your house.

The circuit breakers on the left side of the panel get their power from L1, and the ones on the right get their power from L2.. Each busbar provides 120V.

So how do you get the 240V? Look at the top of the right row of breakers and you’ll see what looks like two breakers that are joined into one by a bar that connects the two switches together. That’s a 240V breaker.

Well, sort of. It doesn’t actually give you 240V. What it does is tap into both of the busbars at the same times, and lets you run two, 120V hot wires to whatever device that breaker breaker powers. The appliance that circuit energizes can combine both to provide 240V or use the individual 120V lines to power individual circuits in the appliance.

So if you want to design an alternative power system to run your whole house through your existing electrical system, you need a system that provides 120V to both L1 and L2, a 240 split phase system as they call it. And no, I can’t just feed 120V from a single source into both busbars at the same time because L1 and L2 are 180 degrees out of phase with one another and that is important. Or so they tell me.

Okay, so what’s with this phase stuff? Well it gets even more complicated and there is a hell of a lot of misinformation out there about what’s generally called “240V split phase”. There are people out there who will try to tell you that you need 240V split phase to power two phase motors, only there really aren’t any two phase motors out there and there haven’t been in many, many years. Or they’ll tell you you need split phase for electronics which is total BS because almost all modern electronics run off DC not AC…

Okay, look, the reason you have split phase coming into your home… Oh, hell, let’s look at what they’re talking about first of all.

AC stands for alternating current, and it’s called that because it, well, alternates. It doesn’t provide a steady positive voltage the way DC does. It alternates from plus to minus at 60 cycles per second. If you were to hook an oscilloscope up to an AC power line what you’d see on the screen is something like what you see in the picture over there on the left.

If you could look at both L1 and L2 at the same time on an oscilloscope it would look something like the picture over there on the right. The two are 180 degrees out of phase.

Why do we even use this system? It would take me pages and pages to explain all of that so I’ll leave it to you to go scurry over to Wikipedia or somewhere and find out for yourself.

So you have two, 120V lines coming in your house and they are 180 degrees out of phase with one another. Sort of. Kinda. And that’s important for, well, reasons, all right? And the two lines can be combined to give you 240V to power bigger appliances. Or not.

Are you confused yet? I am.

But let’s get back to my setup here. Each of the inverters will supply 1 of the two hot lines needed to get 240. And the two inverters “talk” to each other over a communications line so their sine waves are 180 degrees out of phase when in the split phase mode. Which is important for, well, for reasons. Or so they tell me. That’s what we’re stuck with.

But at the moment I don’t want to run any of my 240V appliances off this system. First of all that equipment sucks up huge amounts of power which would drain my batteries fast. The second issue is that my central air conditioning system quite possibly would require more amperage than my batteries can supply. EG4 recommends having at least 5 batteries in order to supply enough amperage to start up a big HVAC system like mine and I only have 3 at the moment.

To make a long story a bit shorter, I have two inverters because I’ll probably almost certainly need a system that can provide more load capacity than a single inverter would give me, and I eventually may want to expand the system to get 240V if I ever get enough batteries and solar panels up to support it.

But I’ve bored you long enough with this. let’s get on with it…

Catching up

One of the things I ordered for this system was a battery cabinet to hold the batteries that has its own built in busbar system for connecting the batteries, and which is also lockable to keep people from fiddling with things they shouldn’t. That was on backorder and I got an email from Signature Solar telling me I could either wait, or they could ship me a slightly different model cabinet. Like everyone else they’re still having supply chain issues. I told them I’d take the different model and that should be here Monday. I jury rigged things together so I could test the inverters and charge the batteries but it can’t stay that way. Once the cabinet arrives I can get the batteries properly configured and start putting everything together.

I have more solar panels on order because my 800 watts of solar is woefully inadequate to keep 15 KWh of batteries charged. Those are supposed to be coming May 15 so I’ll need to build frames to hold all of those.

Gardening Stuff

The weather hasn’t been very good but we’ve managed to get some work done out in the gardens. Once things warm up and the skies clear up we’re going to be really busy. We’re taking out a crumbling stone wall and replacing that, moving two of the raised beds to a new location and a bunch of other stuff going out there. MrsGF has had her indoor greenhouse going down in the basement for weeks already starting plants that will get transplanted outdoors as soon as the weather permits.

Artsy/craftsy stuff

The brewery called me the other day, asking if I’d make more drinks coasters for them. A couple of good friends opened a brewpub, something they’d dreamed of doing for years. So they bought a building with an existing tavern that had enough room for them to put in their brewery and then… Then Covid hit. And somehow they still managed to pull it off and even managed to pay the bills during that whole mess. And now they’re doing pretty well.

Anyway a while back I found some super cheap plain drinks coasters made from wood and some from paperboard and for the heck of it I fired up Photoshop and made some graphics, putting their logo on one side and an allegedly humorous illustration on the other and then used the laser engraver to burn it into the coasters. i thought they looked a bit on the unprofessional side but they were fun to do so I did a few. I never thought they’d actually use them in the bar. But they did, and apparently the customers loved them. And stole them. Which was okay because it’s good PR for the brewery. So I’ve done dozens, maybe a couple of hundred of these things over the last couple of years and I just got a request for more so I got that going on. People are easily amused, I guess.

But enough of this. I need to get going here. I’ve probably put you to sleep already with all of this. I know I’ve nodded off a couple of times myself…