Off-Grid Solar Kit Sizing Calculator
Stop guessing. Enter your daily power needs, location, and backup requirements — get a precise system spec in under 2 minutes. No sign-up, no fluff.
System Sizing Calculator
Results update instantly — no submission required
Step 1 — What's your daily energy consumption?
Use the appliance table below, or enter your total directly if you already know it.
| Appliance | Watts | Hours/day | Wh/day |
|---|---|---|---|
| LED Lighting | 120 | ||
| Refrigerator | 640 | ||
| Phone / Laptop | 240 | ||
| Fan / Small AC | 200 | ||
| Surveillance Camera | 360 | ||
| Custom Device | 0 |
Step 2 — Where will the system be installed?
Peak sun hours (PSH) is the single most important variable in sizing. Getting this wrong causes more undersized systems than anything else.
Step 3 — How many days of battery backup do you need?
This is how long your system can run without any solar input — think consecutive cloudy days or maintenance windows.
Step 4 — Choose your system voltage
Higher voltage = lower current = thinner cables and less heat loss. The right choice depends on your total system power.
Your Recommended Off-Grid System Spec
Based on your inputs — results include a 25% safety margin for real-world conditions
How Real Projects Use This Calculator
Three scenarios I keep coming back to when explaining off-grid sizing to new clients — because the numbers tell the story better than any spec sheet.
Remote Telecom Tower — Indonesia
A telecom operator needed 24/7 uptime for a hilltop repeater drawing 180Wh/day. With 5.2 PSH locally and a 5-day backup requirement (monsoon season), the calculator output: 200W panel + 400Ah AGM battery at 12V.
Off-Grid Cabin — Pacific Northwest, US
A family cabin with 1,800Wh/day consumption, 3.8 PSH (heavy tree cover), and 3-day backup. The calculator flagged the low PSH as the critical constraint — output: 700W array + 450Ah lithium at 24V.
Agricultural Irrigation Pump — North Africa
A 750W pump running 4 hours/day = 3,000Wh/day. With 6.5 PSH and 2-day backup, the 48V system output: 700W panel + 200Ah lithium. The high PSH made this surprisingly compact.
The Math Behind the Calculator
Transparency builds trust — here's exactly how each output is calculated. No black boxes.
1 Solar Panel Wattage
The 1.25 factor accounts for real-world losses: temperature derating (~5%), wiring losses (~3%), inverter inefficiency (~10%), and dust/soiling (~7%). Skipping this margin is how systems end up undersized in summer heat.
2 Battery Capacity
DoD (Depth of Discharge) is 0.8 for lithium, 0.5 for AGM. A 100Ah AGM battery only gives you 50Ah of usable capacity — a common mistake that leads to premature battery failure.
3 Charge Controller
Always oversize the charge controller by 25%. Panel output can spike above rated wattage in cold, clear conditions — a phenomenon called "cold weather boost" that catches many installers off guard.
4 Inverter Size
Peak load is the sum of all appliances that could run simultaneously. The 1.2 surge margin handles motor startup currents — a refrigerator compressor can draw 3–5× its rated wattage for the first 200ms.
Need a Validated System Spec?
Sungold's engineering team reviews your calculator output and provides a certified BOM — free for B2B inquiries. TÜV/UL certified panels, custom voltage options (12V/24V/48V), and Indonesia-origin supply chain to help you avoid AD/CVD duties.
Frequently Asked Questions
The questions I get asked most — answered straight, no padding.
