Ethan BrooksBy Ethan Brooks

Updated November 2026

An off grid solar system PDF is a document that walks you through the design, sizing and wiring of a standalone solar power setup that runs without a utility connection. This guide shows you how to do that math yourself: estimate your daily energy use, size the panels, battery bank and inverter, and lay out the wiring. By the end, you will have the outline of a plan you could save as your own PDF and build from.

What an Off Grid Solar System PDF Should Cover

A useful off grid solar system PDF is more than a diagram. It should give you a sizing worksheet, a parts list, a wiring diagram, and notes on safety and maintenance. Many free manufacturer guides and installer handouts follow this pattern, and it is a good template if you plan to write your own. When you compare an on grid and off grid solar system PDF side by side, the main difference is the battery bank and the absence of a grid tie. An on-grid system feeds power back to the utility and relies on the grid when the sun is down. An off-grid system must supply every kilowatt-hour from its own panels and batteries.

Shopping for one? See our guide: 6 Best DIY Solar Power System Kit Options for Off-Grid Homes (2026).

If you are still deciding between the two designs, read On-Grid vs Off-Grid Solar System: Which Should You Choose? before you commit to a layout.

Step 1: Calculate Your Daily Energy Use

Every off-grid design starts with a load estimate. List each device you plan to run, its wattage, and how many hours per day it operates. Multiply watts by hours to get watt-hours per day, then add the totals.

  1. Find the wattage on each appliance label or manual. For devices with a motor or compressor, use the running watts.
  2. Estimate daily run time honestly. A refrigerator might run about 8 to 10 hours per day in a warm climate, not 24.
  3. Multiply: for example, a 60 W LED light running 5 hours uses 300 Wh.
  4. Add all loads to get your total daily watt-hours.
  5. Add 20 to 30 percent for losses in the inverter, wiring and battery charging.

Suppose your loads total 3,000 Wh per day after losses. That number drives every sizing decision that follows.

Step 2: Size the Battery Bank

Batteries store energy for night use and cloudy days. Most DIY builders size for one to three days of autonomy, depending on how reliable the sun is at their site.

Battery Capacity Formula

Use this formula: Battery capacity (Ah) = (Daily Wh × Days of autonomy) ÷ (Battery voltage × Depth of discharge).

For lead-acid batteries, a depth of discharge of 50 percent is common. For lithium iron phosphate (LiFePO4), 80 to 90 percent is typical. Manufacturers specify the recommended limit for each battery, so check the datasheet.

Using the 3,000 Wh example, one day of autonomy on a 48 V bank at 90 percent DoD gives: 3,000 ÷ (48 × 0.9) ≈ 69.4 Ah, so a 75 Ah to 100 Ah bank at 48 V is a reasonable starting point. Two days of autonomy would roughly double that.

Step 3: Size the Solar Array

Your panels must replace the day’s energy use and recharge the batteries. Use peak sun hours for your location, which you can get from national solar resource maps or local installer data.

Array watts = Daily Wh ÷ (Peak sun hours × System efficiency). A system efficiency of 0.75 is a common planning value that covers wiring, controller and temperature losses.

With 3,000 Wh per day and 4.5 peak sun hours: 3,000 ÷ (4.5 × 0.75) ≈ 889 W. Round up to about 1,000 W of panels, which in practice means several panels wired to suit your charge controller’s voltage window.

Step 4: Choose the Charge Controller and Inverter

The charge controller regulates battery charging from the array. The inverter converts battery DC to household AC. Size the inverter for your largest simultaneous load plus a margin, usually 25 percent above the sum of running watts. Surge ratings matter for motors and compressors. If you want a deeper look at inverter selection, see Off Grid Solar System Inverter: How to Choose and Size One (Step-by-Step).

For controllers, MPPT types generally harvest more energy from the array than PWM types, especially when panel voltage is well above battery voltage. Confirm the controller’s maximum PV input voltage and amperage against your planned string layout before buying.

Step 5: Plan the Wiring

A clean wiring plan prevents most field problems. Typical signal flow runs: panels to combiner or disconnect, then to the charge controller, then to the battery bank, then to the inverter, then to the AC distribution panel. Keep DC cable runs short, because low-voltage high-current paths lose the most energy.

Wiring Checklist

  • Fuse or breaker on every battery positive lead, placed close to the battery
  • DC disconnect between battery and inverter, and between array and controller
  • Cable sized for current and voltage drop (aim for under 3 percent drop)
  • Grounding per local electrical code and the equipment manual
  • Battery terminals torqued to the manufacturer’s specification
  • Labels on every disconnect and breaker

Use a licensed electrician for final connections to a building’s AC panel, and check local permit rules before work begins.

Sizing Summary Table

Component Key input Example result
Daily load Sum of watt-hours plus 25% losses 3,000 Wh/day
Battery bank Daily Wh, autonomy days, DoD, voltage 75 to 100 Ah at 48 V (1 day)
Solar array Daily Wh, peak sun hours, efficiency About 1,000 W
Inverter Largest running load plus 25% margin Sized to peak simultaneous load

Common Mistakes

  • Skipping the load audit and guessing at daily use
  • Ignoring surge loads when choosing the inverter
  • Undersizing the battery bank, which leads to deep discharges and short battery life
  • Using undersized cable and accepting heavy voltage drop
  • Mixing battery types or ages in one bank
  • Forgetting temperature effects on battery capacity and panel voltage

Tips for Building from Your Own PDF

Keep your sizing worksheet in a spreadsheet so you can test scenarios, then export the final plan to PDF for your records. Add a margin for future loads, because most households add devices over time. Record the serial numbers, wire gauges and breaker ratings in your PDF so future repairs are simpler.

  • Victron Energy SmartSolar MPPT charge controller: Widely used in DIY off-grid builds, with a Bluetooth monitoring option that helps you check your daily harvest against your sizing estimate. View on Amazon
  • Renogy 2000W pure sine wave inverter: A common choice for mid-size off-grid loads that need clean AC output for electronics. View on Amazon
  • Klein Tools digital multimeter: Useful for checking battery voltage, panel open-circuit voltage and wiring continuity during commissioning. View on Amazon

FAQ

Is an off grid solar system PDF the same as a sizing calculator?

No. A PDF is a document that presents a plan, while a calculator produces the numbers. Many builders use a spreadsheet to calculate and then export the results to a PDF.

What is the main difference between on grid and off grid solar system PDF plans?

Off-grid plans include a battery bank and sizing for full energy independence. On-grid plans usually omit batteries and focus on grid-tie inverters and utility interconnection.

How many days of battery backup should I plan for?

One to two days is common for homes with reliable sun. Sites with frequent storms or long winter cloud cover often plan for three or more days.

Can I use the same panels for on grid and off grid designs?

Yes, the panels themselves are the same. The controller, inverter and battery configuration differ.

What peak sun hours should I use?

Use the average daily peak sun hours for your worst reasonable month, usually winter, to avoid undersizing. Consult local solar resource data.

Do I need a permit for an off-grid system?

Requirements vary by jurisdiction. Check with your local building department and consult a licensed electrician before connecting to any building wiring.

Which battery chemistry is better for off-grid use?

LiFePO4 offers higher usable depth of discharge and longer cycle life, while lead-acid is lower in initial complexity. Choose based on your budget category, maintenance tolerance and manufacturer specifications.

Conclusion

An off grid solar system PDF works best when it is built from real numbers: your daily load, your sun hours, and your battery autonomy. Follow the steps above to size each component, then document the plan clearly. Before connecting anything to household wiring, have a licensed electrician review the design.

Ready to choose one?

Ethan Brooks

About Ethan Brooks

Ethan Brooks is part of our editorial team and reviews and edits our DIY solar power systems guides, checking product details against manufacturer specifications and owner feedback.