How to Read Your Solar Production and Consumption Data

Your Powerwall app is sitting on a pile of data that most people glance at once a week and never really read. The pretty animated power flow screen is the part everyone looks at. The part that actually saves you money is buried a couple taps deeper.

This is a walkthrough of what those numbers mean and how to turn them into decisions: when to run the dishwasher, whether your battery is sized right, why your bill spiked in a month you swore you barely used the AC.

The four numbers that matter

Before the dashboard makes sense, you need to be solid on a few terms. People mix these up constantly, and the mix-up is usually what's behind a confusing bill.

kW is a rate. kWh is an amount. A kilowatt (kW) is how fast you're pulling or pushing power right now. A kilowatt-hour (kWh) is how much you used over time. Your oven pulls about 3 kW while it's on. Leave it on for two hours and you've used 6 kWh. kW is the speedometer, kWh is the odometer.

Why this matters: your energy charge is billed in kWh. But if you're on a demand rate (more on that below), a second charge is billed on your highest kW, your single worst spike all month. Two completely different numbers, two completely different ways to get charged.

Here's the rest of the vocabulary you'll see on the dashboard:

• Solar: what your panels are producing. Peaks midday, zero at night, droops on cloudy days and in winter.
• Home: your consumption. What the house is actually pulling, regardless of where it comes from.
• Powerwall: battery flow. Positive when charging, negative when discharging.
• Grid: flow to and from the utility. Importing (you're buying) or exporting (you're selling back, if your plan allows it).

Those four are always in balance. At any instant, Solar plus Grid import plus Powerwall discharge has to equal Home plus Grid export plus Powerwall charging. Energy doesn't appear or vanish. Once that clicks, the animated flow screen stops being decoration and starts being a live accounting of where every watt is going.

Reading the dashboard

Open the Tesla app, go to your energy site, and pull up the Energy graph. Switch it to a daily view. You're looking at a stacked chart of those four sources across 24 hours. A normal sunny day with a Powerwall reads like a story in four acts.

Overnight, solar is flat at zero. Your house runs on either the battery or the grid depending on how you've got things set. Around sunrise, the solar line lifts off the floor. By mid-morning it crosses over your home consumption, now you're making more than you're using, and the surplus starts charging the Powerwall. Battery hits 100%, and the extra solar spills out to the grid as export. Late afternoon, solar falls off, the house pulls from the battery you filled earlier, and you coast through the evening on stored sunshine instead of buying expensive peak power.

That's the shape you want. When it doesn't look like that, the deviation tells you something.

A few things to actually look at:

• The crossover points. When does solar start covering your whole house, and when does it stop? Those two times bracket your "free" window. Everything energy-hungry should live inside it.
• Grid import during peak hours. This is the expensive stuff. If you're importing from the grid between, say, 4 and 9 p.m., you're paying top rate. Find out why the battery wasn't covering it.
• Battery state of charge at sunset. If you're hitting evening with the Powerwall at 60%, you've got headroom you're not using. If you're scraping empty by 7 p.m. and importing the rest of the night, the battery's either undersized or being drained too early.

Pull the view out to a month and different things show up. You'll see weekends pull more than weekdays, or a heat wave where consumption doubled, or that stretch of monsoon clouds in July where production tanked and your bill didn't care.

Finding the money in the trends

Single days tell you how the system behaves. Months tell you where the money's leaking. A few patterns worth hunting for.

Self-consumption rate. Of all the solar you produced, how much did your own house actually use versus dump onto the grid? Add up home-covered-by-solar plus battery-charged-by-solar, divide by total production. If a big chunk of your solar is exporting at midday and you're buying it back at night, that's a timing mismatch. Under net metering that might be fine. Under a plan where export credits are worth less than what you pay to import (most newer plans), every exported kWh you buy back later is a small loss.

Your demand peak. If you're on a plan with a demand charge (SRP's E-27 and APS's demand plans in Arizona, parts of the commercial rates in California), there's a number on your bill measured in kW, not kWh. It's set by your single highest spike in any 30- or 60-minute window during peak hours. One afternoon where the AC, oven, and EV charger all ran at once can set a demand peak that costs you $15–$20 per kW for the whole month. The app's power history shows you exactly when that spike happened. Usually it's a stack of big loads colliding for fifteen minutes.

Seasonal production drop. Compare a June production day to a December one. In Phoenix you'll lose a meaningful share of daily output to the shorter, lower-angle winter sun. If your winter battery is running dry every evening but summer's fine, that's not a fault. It's the season, and it changes how aggressively you should be shifting load in those months.

The phantom baseline. Look at your home consumption at 3 a.m. when nothing should be running. That flat overnight floor is your always-on load: networking gear, the fridge, standby electronics, a pool pump if it's on a bad schedule. Knock 200 watts off that baseline and you've saved roughly 5 kWh every single day without changing how you live.

Turning data into rules

Reading the data is step one. The point is to act on it, and most of the action is just shifting when things happen so your stored solar covers the expensive hours instead of the grid.

You can do some of this by hand in the Tesla app. Time-Based Control lets you tell the Powerwall your rate plan's peak and off-peak windows so it prioritizes discharging during peak and holds charge otherwise. If you've got an EV, scheduling it to charge inside your solar window instead of at 6 p.m. is the single biggest change most people can make.

The manual approach has a ceiling, though. Your rate windows shift by season. Demand charges need the battery to actively flatten spikes in real time, not just discharge on a fixed schedule. Watching the app and adjusting settings by hand doesn't scale past a few tweaks.

That's where Grid Getter comes in. It reads the same data you've been looking at and runs your Powerwall against it automatically. DemandGuard watches your real-time power draw and discharges the battery to shave demand spikes before they set your monthly peak, the kind of fifteen-minute collision that quietly adds $40 to a bill on a demand plan. The automation engine matches discharge to your specific plan's peak windows (E-27, R-3, TOU-D-PRIME, whatever you're on) and adjusts as rates and seasons change, so you're not re-reading charts every month to stay optimized.

The data you've been reading is exactly what these rules run on. You're just handing the watching-and-reacting part to something that does it every second instead of once a week.

Start here

Open the Tesla app tonight after sunset and check one number: your Powerwall's state of charge. If it's near empty and you've still got hours of peak pricing left, you're buying grid power you could have stored for free that afternoon. If it's still high, you've got capacity you're not putting to work. Either way, that one reading tells you whether your system is timed to your rate plan or just running on defaults.

Want the watching done for you? See what Grid Getter can do with your data for free.