Shed Solar Calculator
Pick your shed type, select your loads, and get panel, battery, and inverter specs in seconds. Results update live — no submit button needed.
What's in your shed?
How This Calculator Works
Load estimation
Each appliance has a rated wattage and a daily usage slider. Daily watt-hours (Wh) = watts × hours. The calculator sums all enabled loads to get total daily Wh.
Panel sizing formula
Panel DC watts = (Daily Wh ÷ Peak Sun Hours) × 1.15
The 1.15× factor covers MPPT efficiency losses (~6%) and miscellaneous wiring losses (~5%). Peak sun hours default to 4h (average U.S.) — adjust with the sun tier selector.
Battery sizing formula
Battery Wh = Daily Wh × 1.25 ÷ 0.80
1.25 days of autonomy (one cloudy day buffer). LiFePO4 at 80% depth of discharge. Results are in usable Wh — divide by battery voltage to get Ah.
Inverter sizing
Inverter minimum = sum of AC surge watts across all enabled loads. This is the peak draw the inverter must handle at startup. For tools with motors (saws, compressors), surge can be 2–3× rated watts.
System tiers
Tier 1 Lighting(<250W): LEDs, phone chargers, small electronics. 12V DC systems work well here.
Tier 2 Tools (250–600W): Drills, laptops, fans. 12V or 24V depending on inverter size.
Tier 3 Workshop(>600W): Power saws, compressors, angle grinders. 24V systems strongly preferred above 400W panels.
FAQ
How many solar panels does a shed need?
A basic storage shed with 2 LED lights and a phone charger needs 30–60W. A workshop with power tools needs 400–800W. The calculator above sizes panels to your exact load.
What size battery do I need for a shed solar system?
A she-shed with laptop and lights typically needs 150–300Wh usable. A cabin with a mini fridge needs 600–1,000Wh. The calculator uses 1.25 days autonomy with LiFePO4 at 80% DoD — the standard for DIY shed builds.
Do I need an inverter for a shed solar system?
Only if you're running AC appliances — power tools, fans, laptop brick chargers. A lighting-only shed can run 12V DC with no inverter at all. Add one when you have AC loads.
Should I use 12V or 24V for my shed?
12V works for loads under ~1,500W. Above that, wire losses get expensive and 24V is more efficient. The calculator flags when your load suggests upgrading to 24V.