Hurricane Isaias is in the Gulf this morning, and the Hurricane Center has it approaching the northern Gulf Coast on Friday. The track will move. It always does. Where that cone sits on Friday is not something I can do anything about from Gulf Breeze.
What I can do something about is how full our battery is when the grid drops. So this morning I opened the EG4 portal and changed one number. On Grid EOD SOC, set to 90.
Why the battery is not full when you need it
On a normal day a hybrid system charges the battery in the sun and runs the house off it after dark, down to whatever floor you set. That is the daily cycle that keeps the power bill down, and it is the reason most people buy the battery in the first place.
The catch is the clock. The grid tends to drop in the worst hour. The front comes through at two in the morning, a limb takes the line down, and you island onto a battery that has been feeding the house since sunset. You start the outage with whatever the evening left in it.
Two settings decide this on an EG4 inverter, as long as Discharge Control is set to SOC and not voltage. They sit together in the Discharge Setting panel of the monitoring portal.
On Grid EOD SOC is the floor while the grid is up. EOD is end of discharge. Set it to 90 and the inverter stops drawing the battery down past 90% as long as utility power is there. After dark the house runs on the grid instead of the battery, and the battery sits near full, waiting.
Expect one thing the moment you click Set. If the battery is sitting below 90% right then, the house switches straight to grid power and stays on it until the panels bring the battery back up past 90%. That is the setting doing its job. From then on the battery carries the house in the evening only down to 90, and the grid picks up the rest of the night.
Discharge Cut-off SOC is the floor when the grid is gone. Ours is set to 5. That is as far down as I will let the bank go in an outage before the inverter stops pulling from it.
The space between those two numbers is the storm reserve. On a normal week I let the battery work for its living. This week it holds 90% in the tank, spends it only if the lights actually go out, and then it can spend nearly all of it.
What it costs you
For the next few days the battery is not covering our evenings, so that slice of the bill goes back to the utility. On our place that is a few dollars a night. Cheap insurance against starting an outage half empty.
The other cost is remembering to put it back. A battery parked at 90% all winter is a battery you paid for and are not using. Once the storm has passed and the grid has settled down, go back in and set On Grid EOD SOC to wherever you normally run it. Put a reminder on your phone the minute you make the change, because nobody remembers a settings page.
How to do it
- Log in to the EG4 monitoring portal on a computer.
- Pick your station and the inverter serial at the top of the page, then click Read so the page shows the live values and not the last ones it cached.
- Scroll to Discharge Setting. Make sure Discharge Control says SOC. If it says voltage, the voltage boxes are the ones in charge and the percent boxes are greyed out.
- Type 90 in the On Grid EOD SOC (%) box and click the Set button next to it.
- Look at Discharge Cut-off SOC (%). Ours reads 5. If yours is set higher you are trading a little runtime for a cushion, and that is a fair trade too. Leave it unless you know why you want it lower.
- Click Read again and make sure both numbers took.
If you have more than one inverter, step through every serial in the dropdown. Each one carries its own settings.
If the names on your screen do not match these, the labels shift a little between EG4 models and firmware versions. Text a photo of your Discharge Setting panel to the shop at 850-530-1872 and we will tell you which box is which.
If your system is off-grid with no utility feed, On Grid EOD SOC does nothing for you. Your floor is the Discharge Cut-off SOC, and your prep is a full charge and fresh fuel in the generator.
The rest of the list
The battery floor is the one people miss, because it lives on a settings page nobody opens. The rest of the list is the same one we ran on June 1, and it is in the season opener. Top the battery off. Run the inverter off-grid for fifteen minutes with the fridge and the well pump on, so a trip happens now and not Friday night. Fresh fuel in the generator. Photos of the panels, the inverter, the disconnect, and the meter for the insurance claim you hope you never file. And the one-page list of what stays on, taped inside the breaker panel cover. If you have not made that list yet, this post walks through it.
Set the floor to 90. Check the cutoff. Click Read. Put it back next week.
If you bought your system from us and want a second set of eyes on the settings before Friday, call or text the shop at 850-530-1872 and we will walk through it with you.
Ready for Anything.