Design your DIY solar
system in minutes.

Enter your loads, pick your system voltage, and get a complete parts list β€” sized exactly for your build.

Accurate load calculations
Battery bank sizing
Solar array recommendation
Charge controller sizing
Wiring diagram
Real product database DB
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System type
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Loads
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Location
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Sizing
5
Parts list
● Unsaved design
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What are you powering?
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RV / Van
Mobile, 12V ideal
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Cabin / Shed
Small off-grid
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Off-Grid Home
Full home, no grid
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Grid Backup
Hybrid / grid-tie
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Grid-Tied + Storage
HV hybrid system
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Marine / Boat
Saltwater-rated
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Custom
Build from scratch
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System voltage
12VRV / Marine
24VRV / Van
48VRecommended
ℹ️ 12V is standard for RVs, vans and boats. Simple to wire, lots of native 12V appliances. Best for systems under 1.5kW.
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AC grid / market
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Split-phase
120/240V β€” North America
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Single-phase
230V β€” Europe / International
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Three-phase
400V β€” EU industrial / farm
ℹ️ 230V single-phase 50Hz is used across Europe, Australia, most of Africa, Asia and South America. Standard for most residential off-grid systems worldwide.
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Saved Designs β€” save up to 5 scenarios to compare
Save as new design:
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Quick-add common appliances β–Ά
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Your appliance list
Appliance Watts Qty Hrs/day Wh/day SurgeΓ—
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Wh/day total
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Peak watts
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Surge watts
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Avg watts
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Sun hours & location
πŸ“… Annual avg
❄️ Winter
⚠️ Worst month
β˜€οΈ Summer
✏️ Custom
JanFebMarAprMayJun JulAugSepOctNovDec
4.0
Hours of full equivalent sunshine per day
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Panel tilt & shading
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Autonomy & battery design
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System wiring overview
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Safety & code checklist
    Affiliate disclosure: This page uses affiliate links to products. We earn a small amount from qualifying purchases at no extra cost to you. All recommendations are based on specs and community reputation only.
    Affiliate disclosure: This page uses affiliate links to products. We earn a small amount from qualifying purchases at no extra cost to you. All recommendations are based on specs and community reputation only.
    ℹ️Showing HV hybrid systems. Battery and inverter compatibility is enforced β€” only verified pairings are shown together. Select a battery to see matching inverters.

    LiFePO4 Battery Builder

    Configure DIY cell packs β€” series/parallel counts, BMS sizing, and full pack specs from the database.

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    Cell configuration from DB
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    Pack specifications
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    BMS recommendations from DB

    DC Wire Sizer

    Find the correct wire gauge for any DC run. Imperial AWG and metric mmΒ² shown side by side.

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    Circuit parameters
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    Wire sizing results
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    Fuse sizing guide
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    Recommended wire & connectors from DB

    Solar Education

    Essential concepts for designing and building reliable DIY solar systems.

    ⚑
    Key formulas
    FormulaUse
    W = V Γ— AWatts from volts & amps
    Ah = Wh Γ· VAmp-hours from watt-hours
    Battery kWh = V Γ— Ah Γ· 1000Battery energy capacity
    Panel W = Daily Wh Γ· (PSH Γ— Ξ·)Required solar watts
    MPPT A = Panel W Γ· Bat V Γ— 1.25Charge controller sizing
    Voc_cold = Voc Γ— (1 + Tc Γ— Ξ”T)Cold temp Voc correction
    VD = 2 Γ— L Γ— I Γ— R/1000Voltage drop in wire run
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    LiFePO4 vs Lead Acid
    LiFePO4Lead Acid
    Cycle life2,000–6,000300–500
    Usable DoD80–100%50%
    WeightLightHeavy
    Cost/kWh~$150–250~$100–150
    MaintenanceNoneWater top-up
    Cold performanceDischarge OK to βˆ’10Β°C; no charging below 0Β°C without self-heatingCharges below 0Β°C but loses 30–50% capacity at βˆ’10Β°C
    VerdictLiFePO4 wins long-term
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    Voltage comparison
    VoltageBest forNotes
    12VRV, van, boat under 1.5kWNative 12V appliances; high current needs thick wire
    24VRV, campervan, small off-gridGood for mobile setups. For homes and cabins, 48V is recommended for better efficiency and equipment choice.
    48VEverything else4Γ— less current = 4Γ— smaller wire. Better inverter efficiency. Industry standard for home/cabin.
    β˜€οΈ
    Peak sun hours by city
    LocationAvg PSH
    Phoenix, AZ6.5 h
    Miami, FL5.5 h
    Denver, CO5.1 h
    New York, NY4.1 h
    Seattle, WA3.2 h
    London, UK2.8 h
    Helsinki, FI2.5 h
    Sydney, AU5.8 h
    Cape Town, ZA5.5 h
    ⚠️
    Top beginner mistakes
    • !
      Undersizing wire β†’ heat and fire risk. Always size for 125% of continuous load.
    • !
      No fuse within 18 in / 460 mm of battery terminal β†’ unprotected short circuit path.
    • !
      Mixing old and new batteries or different cell batches β†’ destroys the whole bank.
    • !
      Panels partially shaded β†’ kills entire string output. Use MPPT + shade-tolerant wiring.
    • !
      Skipping BMS on DIY LiFePO4 cells β†’ overcharge, cell damage, or fire.
    • !
      Not top-balancing cells before first use β†’ imbalanced pack from day one.
    • !
      Modified sine wave inverter with motors / medical equipment β†’ overheating.
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    Trusted resources

    PV String Voltage Calculator

    Prevent MPPT damage. Cold temperatures raise panel Voc β€” a string that looks safe at 25Β°C can destroy your charge controller at βˆ’20Β°C. Check before you wire.

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    Panel selection from DB
    Used for MPPT voltage safety
    Used for power & Vmp calculations
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    String configuration
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    1
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    Temperature range
    βˆ’20Β°C
    60Β°C
    ℹ️ Use the coldest morning temperature you could ever experience at this location β€” not the average winter low. For MPPT safety, use the record low. Panels can reach +70–85Β°C in direct sun on hot days (cell temp = ambient + ~25–35Β°C).
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    String voltage analysis
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    Voc vs temperature β€” string voltage curve
    String Voc String Vmp MPPT max voltage
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    Maximum safe series count for your MPPT