The Homestead Calculator

The most common solar planning mistake isn't buying the wrong panels. It's not knowing your load before you buy anything. People start with "how many panels do I need?" when the actual first question is "how many watt-hours per day do I use?" Everything else — panel count, battery bank, inverter size — follows directly from that one number.

This guide walks through how to figure out your load honestly, what the components of an off-grid system actually do, and what a realistic system looks like for a homestead that isn't trying to replicate a suburban lifestyle on solar.

What "Off-Grid" Actually Means for Energy

Off-grid doesn't mean you live without electricity. It means you generate and store your own. The practical difference from grid-tied living is that you have a finite daily budget — the sun gives you a certain amount of energy each day, your batteries hold a certain reserve, and if you exceed both, you go dark.

That constraint forces a clarity that most people actually appreciate once they're living it. You stop leaving things plugged in. You run the washing machine during peak sun hours. You think about what you actually need to power and what you don't. For a homestead, that shift in mindset is often part of the point.

Step 1: Build Your Load List

Go through your home or planned structure and list every electrical device you intend to run. For each one, you need two numbers: how many watts it draws, and how many hours per day you'll actually run it. Multiply those together to get watt-hours per day for that device.

Here are typical loads for a modest off-grid homestead setup:

That last one — the brooder lamp — is a reminder that some homestead loads are seasonal and significant. A heat lamp running 16 hours a day for six weeks is a major draw. Plan for your peak season, not your average day.

Step 2: Add It Up and Apply the Loss Factor

Once you have your watt-hours per day, add 25% to account for real-world losses — wire resistance, inverter inefficiency, temperature effects on panels, and the fact that batteries don't charge or discharge at 100% efficiency. A system that needs 3,000 Wh/day of usable power needs to generate roughly 3,750 Wh/day from the panels to actually deliver that.

Step 3: Figure Out Your Panel Count

Panels are rated at their peak output under ideal laboratory conditions. Real-world output depends on your location's peak sun hours — the number of hours per day when sunlight is strong enough for full panel output. This is not the same as daylight hours.

Tennessee averages about 4.5 peak sun hours per day annually — higher in summer, lower in winter. That seasonal variation matters a lot: a system sized for summer sun will struggle in December. For an off-grid system, size for your worst-case winter month, not the annual average.

The math: Adjusted daily load (Wh) ÷ peak sun hours ÷ panel wattage = number of panels needed.

At 3,750 Wh/day adjusted load in Tennessee (4.5 peak sun hours), with 400W panels:

3,750 ÷ 4.5 ÷ 400 = 2.08 panels. Round up to 3, add a buffer panel, and you're running a 4-panel, 1,600W array for a modest setup.

A more realistic full-homestead system — chest freezer, water pump, lights, charging, washing machine — typically lands in the 8–16 panel range for a Tennessee location.

Step 4: Size Your Battery Bank

Batteries are what keep you running through the night and through cloudy stretches. The standard guidance for off-grid systems is to size for 2–3 days of autonomy — meaning your battery bank holds enough energy to run your loads for 2–3 days with no solar input at all.

Lithium iron phosphate (LFP) batteries are the current standard for off-grid homesteads. They can discharge to about 80% of their capacity without damage, they last 10+ years, and they handle temperature variation well. Lead-acid batteries are cheaper upfront but can only discharge to 50%, weigh considerably more, and need more maintenance.

Battery bank sizing: Daily load (Wh) × days of autonomy ÷ depth of discharge = total battery capacity needed.

For a 3,000 Wh/day load, 3 days autonomy, 80% DoD: 3,000 × 3 ÷ 0.80 = 11,250 Wh (11.25 kWh) of battery storage.

Step 5: Choose Your Inverter

Your inverter converts DC power from your panels and batteries into the AC power your appliances use. Size it for your peak simultaneous load — not your average load. If your well pump (750W), washing machine (500W), and refrigerator (150W) could all run at once, your peak load is 1,400W. Size your inverter to at least 1.5× that: a 2,000W inverter minimum.

For most homesteads, a 2,000–4,000W pure sine wave inverter with built-in MPPT charge controller (an all-in-one unit) is the cleanest setup. Brands like Victron, Renogy, and EG4 make units designed for off-grid use that include battery management, solar charge control, and AC output in a single box.

What a Real Off-Grid Homestead System Costs

For a modest but functional off-grid homestead — chest freezer, lights, charging, water pump, electric fence, washing machine — budget roughly:

• 4–8 panels (400W each): $800–$1,800
• 10–20 kWh battery bank (LFP): $4,000–$8,000
• Inverter/charger (2–4kW): $600–$1,500
• Mounting, wiring, fuses, charge controller: $500–$1,200
• Total DIY: $6,000–$12,000

That range is wide because the battery bank is the biggest variable. Going from 10 kWh to 20 kWh of storage nearly doubles the battery cost while barely changing anything else. Know your autonomy needs before you spec the batteries.

Installed by a contractor, add 50–100% to the hardware cost for labor and permitting. The 30% federal Investment Tax Credit applies to installed systems — worth factoring in if you're going the professional route.

The Honest Starting Point

If you're in the planning stages and not yet on your land, the most useful thing you can do right now is start tracking your current energy use. Pull up your electric bill, look at your monthly kWh consumption, and divide by 30. That's your current daily load baseline. Then go through it item by item and decide what you'd run differently off-grid.

Most families planning an intentional off-grid homestead end up targeting 2–5 kWh per day once they've made deliberate choices about propane cooking, wood heat, and line-drying clothes. That's a very achievable system at a reasonable cost — especially in a state like Tennessee with solid solar resources.