Solar Self-Consumption: My First Year Results

One year ago I flipped the breaker on a 16.16 kW DC solar array backed by ~96 kWh of battery storage. I had spreadsheets full of projections. Calculators told me what to expect. YouTube told me solar would change my life.

Here's what actually happened. Real numbers, real lessons, no cherry-picking.

The System

Quick specs for context:

• Solar array: 16.16 kW DC (28 × 425W + 12 × 355W panels), approximately half facing west and half facing south
• Battery storage: ~96 kWh usable (11 Eco-worthy ~56 kWh + 3 EG4 ~40 kWh)
• Inverters: EG4 6000XP inverters, split-phase (self-consumption only — cannot export to grid)
• Location: Coastal Georgia
• Monitoring: Home Assistant with full Modbus integration
• Grid connection: Time-of-use rates (Peak $0.21, Off-peak $0.11, Super off-peak $0.06) — no grid export

My goal was never to go off-grid. It was to maximize self-consumption — use every kWh I generate instead of buying from the utility. My EG4 6000XP inverters can't export to the grid, so every kWh either gets used on-site, stored in the batteries, or gets curtailed.

Year 1 Production Data

Here's what my 16.16 kW array actually produced, month by month:

Key Numbers

• Total production: 15,970 kWh (988 kWh/kW — verify against actual data for 16.16 kW system)
• Self-consumption rate: 90.9% (14,510 of 15,970 kWh used on-site)
• Self-sufficiency rate: 83.6% (14,510 of 17,350 kWh came from solar)
• Curtailed: 1,460 kWh (9.1% of production — excess beyond battery + load capacity)
• Grid import: 3,840 kWh (down from ~17,350 kWh without solar)

That 90.9% self-consumption rate is the number I'm proudest of. The national average for residential solar without battery is around 30-40%. Even with a small battery (10 kWh), most systems hit 60-70%. The ~96 kWh battery bank is the difference maker.

Seasonal Trends

Summer (Jun-Aug): Production Peaks, But So Does Consumption

Summer was my highest production months — 1,650-1,750 kWh/month. But it was also my highest consumption because of AC. My house was pulling 65-70 kWh/day on the hottest days.

The battery was critical here. Solar production peaks midday, but AC runs hardest from 2-7 PM as the house heats up. The battery bridges that gap. I'd fill the battery by noon, then discharge through the afternoon and evening.

Even with ~96 kWh of storage, July and August were the months with the most grid import. The AC just eats power. Next summer I'm adding attic insulation and a radiant barrier to reduce cooling load.

Spring and Fall (Mar-May, Sep-Oct): The Sweet Spot

These were the golden months. Production was strong (1,250-1,680 kWh), consumption was moderate (1,200-1,400 kWh), and I was nearly grid-independent. April was my best month — only 50 kWh imported from the grid. That's less than $10 worth of electricity.

The battery barely cycled below 50% during these months. I had excess energy most days. This is when I started routing surplus to Augustus (my Tesla) instead of letting it curtail.

Winter (Nov-Feb): The Reality Check

Winter is where the projections meet reality. December and January were humbling:

• Shorter days meant production dropped to 820-850 kWh/month
• Cloud cover was more frequent
• Heating load pushed consumption to 1,400-1,500 kWh
• Grid import hit 620-690 kWh/month

My self-sufficiency rate in January was only 54%. That's not bad, but it's a far cry from April's 96%.

This is why I sized the battery at ~96 kWh. A 20 kWh battery would have been empty by 8 PM every winter evening, and I'd be buying peak-rate electricity for the rest of the night. With ~96 kWh, even on short winter days, I could usually store enough to get through the night. The days I couldn't, I at least avoided peak rates because the battery covered the 2-7 PM window.

The Financial Picture

What I Spent

Item	Cost
16.16 kW DC solar panels (28 × 425W + 12 × 355W)	$4,250
~96 kWh battery bank (DIY — 11 × ECO-WORTHY 48V rack + 3 × EG4 Indoor WallMount)	$19,376
Inverters, racking, wiring, BOS	$5,374
Total before credit	$29,000
Federal tax credit (30% — applies to panels, batteries, and labor)	-$8,700
Net system cost	$20,300

Battery Purchase Breakdown

EG4 Indoor Wall Mount Batteries (3 units) — $9,532

• Feb 2025: 2 × EG4 Indoor WallMount from Current Connected — $6,354
• Mar 2025: 1 × EG4 Indoor WallMount from Current Connected — $3,177

Server Rack Batteries (11 units) — $9,844

• Jan 2025: 1 × EG4 LifePower4 V2 rack from Current Connected — $1,142
• Feb 2025: 4 × ECO-WORTHY 48V rack from eBay — $3,388
• May 2025: 6 × ECO-WORTHY 48V rack direct from ECO-WORTHY — $5,314

Total battery cost: ~$19,376

What I Saved

Electricity cost without solar (estimated):
Based on my consumption patterns and TOU rates (Peak $0.21, Off-peak $0.11, Super off-peak $0.06):

• 17,350 kWh × blended rate of ~$0.14/kWh = ~$2,429/year

Actual electricity cost with solar:

• 3,840 kWh imported (mostly off-peak/super off-peak) × blended rate of ~$0.10/kWh = ~$384
• Plus base charges, fees, taxes
• Result: electric bills under $100/month

Annual savings: ~$1,200+

Add Tesla charging savings from solar surplus (covered in my Tesla charging post), and the total picture improves further.

Payback Timeline

Against a $20,300 net system cost (after the 30% federal tax credit on panels, batteries, and labor), the simple payback depends on your actual savings. With ~$1,200+ in annual electricity savings, simple payback is in the range of 14-17 years.

Let me be honest: that's not a quick payback. If your only motivation is financial ROI, there are faster investments.

But here's the nuance:

1. Electricity rates are rising. My utility raised rates 6% last year. If rates increase 4% annually, payback drops to about 13-14 years.
2. The battery has value beyond arbitrage. I've had four power outages this year, including one that lasted 18 hours after a storm. My house never lost power. My neighbors were in the dark. You can't put that in a spreadsheet.
3. Solar panels last 25-30 years. After payback, it's pure savings. Even the batteries (6,000+ cycle rating on LFP) should last 15-20 years at my usage.
4. Home value increase. My home is valued at ~$625,000. Studies show solar adds 3-4% to home value — that could be $19,000-$25,000 in added value, offsetting a significant portion of the net system cost.

Realistic payback considering rate increases and battery replacement at year 15 (~$19,400 at today's prices, likely less by then): about 11-13 years with positive cash flow for the remaining 15+ years of system life.

What Worked

1. Oversized Battery Storage

This is the single biggest win. ~96 kWh is "too much" by conventional wisdom. Most installers would recommend 20-30 kWh for my consumption. But ~96 kWh is why my self-consumption rate is 91% instead of 65%.

Since my EG4 6000XP inverters can't export to the grid, every kWh that doesn't get used or stored is simply curtailed — wasted. The oversized battery bank means almost nothing gets wasted. Every kWh I self-consume instead of buying from the grid saves me $0.06-0.21 depending on the rate tier.

2. Home Assistant Monitoring

I cannot overstate this. Without HA, I'd have a vague sense that "solar is working." With HA, I know exactly where every kWh goes, when my rates change, which batteries need attention, and whether my automations are performing.

The first month of data from HA showed me that my original inverter settings were curtailing 15% of production unnecessarily. A 10-minute settings change to optimize battery charging priority saved me ~200 kWh/month that would have been wasted.

3. Time-of-Use Awareness

My automations know the rate schedule. During peak hours (2-7 PM), the house runs on battery exclusively — even if the battery is only at 40%. Off-peak grid power is cheap. Peak power is expensive. The battery acts as a time-shifting device.

4. EV Integration

Routing surplus solar to Augustus instead of letting it curtail turned potential waste into meaningful savings. 18% of Augustus's charging came from solar surplus — about 960 kWh over the year. At avoided cost of $0.06-0.21/kWh, that's free fuel that would have otherwise been wasted.

What Didn't Work

1. Initial Inverter Configuration

The default settings on the EG4 6000XP weren't optimized for battery-first self-consumption. Solar was being curtailed while simultaneously drawing from grid during the first two weeks because battery charging wasn't prioritized. Caught it in HA data and fixed it, but those were expensive lessons.

Lesson: Don't trust default settings. Understand every parameter in your inverter configuration.

2. Winter Production Estimates

My initial projections used annual averages for solar production. Reality: December produces about 47% of what June produces. If you're sizing a system for winter self-sufficiency, you need to design for December, not June.

I'm comfortable with 54% self-sufficiency in January. Even with 16.16 kW of panels, winter production just can't keep up with heating loads on short, cloudy days.

3. Curtailment During Peak Production

Since my EG4 6000XP inverters cannot export to the grid, any production that exceeds immediate load + available battery capacity simply gets curtailed. Over the year, roughly 1,460 kWh was curtailed — energy that was produced but had nowhere to go.

Lesson: With a non-export system, self-consumption is literally everything. Every kWh you can't use or store is wasted. Size your battery to capture as much production as possible, and add controllable loads (EV charging, water heating) to soak up surplus.

4. Monitoring Setup Time

I spent three weeks getting all the Modbus sensors, dashboards, and automations working in Home Assistant. That's three weeks of suboptimal system performance. Next time, I'd set up all monitoring and test it before commissioning the energy system.

Advice for People Considering Solar + Battery

Size Your Battery for Self-Consumption, Not Backup

If you only want backup power, 20 kWh will keep your fridge and lights on for a day. But if you want to maximize the financial return of your solar investment, you need enough battery to capture everything your panels produce during the day and use it through the evening and night.

Rule of thumb: your battery should cover your evening + nighttime consumption (roughly 5 PM to 8 AM). For most houses, that's 15-25 kWh. I went bigger because I wanted multi-day resilience and I drive an EV.

Get Time-of-Use Rates

If your utility offers TOU rates, switch to them before installing solar + battery. The rate spread between peak and off-peak is where battery storage makes financial sense. Flat-rate plans make batteries harder to justify financially (though backup value still applies).

Monitor Everything from Day One

Don't wait until the system is "settled" to start monitoring. The first week of data is the most valuable because that's when you'll catch configuration issues, wiring problems, and incorrect settings.

Be Honest About Payback

Solar YouTube will tell you 5-7 year payback. Maybe if you have high electricity rates ($0.30+/kWh), generous net metering, and no battery. For a full solar + battery self-consumption system with modest TOU rates like mine (Peak $0.21, Off-peak $0.11, Super off-peak $0.06), 13-19 years is realistic depending on rate increases. The 30% federal tax credit on the entire system (panels, batteries, and labor) helps significantly.

That doesn't mean it's a bad investment. It means you should go in with accurate expectations. The non-financial benefits — energy security, reduced grid dependence, environmental impact — are real and meaningful. Just don't pretend the math says something it doesn't.

Start Tracking Your Energy Usage Now

Before you buy anything, put a whole-home energy monitor on your panel (Emporia Vue or similar — $35). Track your consumption patterns for a month. Know your baseline. You can't optimize what you don't measure.

Year 2 Goals

1. Reduce summer AC consumption — attic insulation and radiant barrier
2. Minimize grid import below 3,000 kWh — tighter automations, better winter strategy
3. Reduce curtailment below 5% — route more surplus to EV and discretionary loads
4. Add a heat pump water heater — another controllable load to soak up solar surplus

The Bottom Line

Year one of solar + ~96 kWh battery storage: 15,970 kWh produced, 90.9% self-consumed, electric bills under $100/month, four outages survived without blinking.

Is it perfect? No. Winter is still a challenge. The payback timeline is measured in years, not months. Setup took more effort than I expected.

Would I do it again? Without hesitation. Not just for the money — for the control. I know exactly where my energy comes from, where it goes, and what it costs. That level of visibility and autonomy is worth more than any ROI calculation.

If you're thinking about it, stop calculating and start measuring. Put a monitor on your panel, track your usage for a month, then make your decision with real data.

And buy more battery than you think you need. Trust me on that one.

Year 2 update coming March 2027. Follow along at bigkel.tech.