Everything you need to size, plan, and understand your off-grid energy system. Engineering-grade calculators, reference guides, and glossaries — built by engineers, designed for every skill level.
Tools & Calculators
Tool 01
Off-Grid Solar System Sizing Calculator
Enter your appliances and daily usage, set your battery chemistry, peak sun hours, and autonomy days — and get a complete system specification: solar panel wattage, battery bank size, inverter rating, and MPPT charge controller in one pass.
Solar panelsBattery bankInverterMPPTAll skill levels
Enter your daily load, battery cell Ah rating, depth of discharge, and autonomy days to get your exact bank configuration — series/parallel layout, usable kWh, runtime scenarios at different loads, and charge time from solar, grid, or generator.
Three tools in one: size your MPPT charge controller using absorption voltage (not nominal), find every valid panel array configuration for your specific MPPT limits, and calculate exactly how fast your solar system pays back against a generator with Nigerian fuel escalation built in.
Build your appliance list with load types, and get the minimum continuous rating, peak surge capacity, and DC current draw your inverter must handle. Includes a full voltage window setpoint table for LiFePO4, NMC, and lead-acid batteries — correctly coordinated between MPPT, inverter, and BMS.
Check whether your inverter can handle your full load including motor surge with thermal derating applied, and size a generator correctly for hybrid off-grid operation. Get the exact AC input current limit to set in VEConfigure for your Victron or Deye inverter-charger, with PowerAssist analysis included.
Three precision tools in one: size cables per IEC 60364‑5‑52 or NEC, verify voltage drop, and select the correct fuse or breaker — all with automatic derating for temperature, grouping, and insulation type. Essential for safe, code‑compliant installations.
The percentage of a battery’s total capacity that has been used. A 100 Ah LiFePO4 at 80% DoD has delivered 80 Ah and should now be recharged.
PSH — Peak Sun Hours
The number of hours per day when solar irradiance averages 1,000 W/m². This single number drives your entire panel array size. Nigeria averages 4.5–5.5 PSH depending on location.
C-rate
The charge or discharge current relative to battery capacity. A 1C rate on a 200 Ah battery equals 200 A of current. LiFePO4 is typically rated at 0.5–1C continuous discharge.
SOC — State of Charge
Your battery’s current charge level as a percentage. 100% = fully charged, 0% = fully discharged. Most inverters display SOC — but voltage-based SOC readings are inaccurate under load.
MPPT — Max Power Point Tracking
A charge controller algorithm that continuously adjusts the panel’s operating voltage to extract maximum power regardless of temperature or partial shading.
Wp — Watts Peak
A solar panel’s rated output under Standard Test Conditions: 1,000 W/m² irradiance, 25°C cell temperature. Real-world output in Nigeria is typically 75–85% of this figure.
Voc — Open-Circuit Voltage
The voltage a solar panel produces with no load connected. Rises in cold weather. Your MPPT Voc max rating must exceed this — which is why a 20% safety margin is mandatory.
BMS — Battery Management System
The electronics that protect a lithium battery bank from overcharge, over-discharge, overcurrent, and thermal events. It is the last line of defence in your battery system.
Autonomy Days
The number of consecutive days without solar input your battery bank can sustain your load. For Nigeria, 2 days is a common design target to account for cloudy weather.
New tools and guides added regularly
Subscribe to get notified when new calculators, reference guides, and downloads go live. No spam — just useful updates for off-grid engineers and DIYers.
Contains information related to marketing campaigns of the user. These are shared with Google AdWords / Google Ads when the Google Ads and Google Analytics accounts are linked together.
90 days
__utma
ID used to identify users and sessions
2 years after last activity
__utmt
Used to monitor number of Google Analytics server requests
10 minutes
__utmb
Used to distinguish new sessions and visits. This cookie is set when the GA.js javascript library is loaded and there is no existing __utmb cookie. The cookie is updated every time data is sent to the Google Analytics server.
30 minutes after last activity
__utmc
Used only with old Urchin versions of Google Analytics and not with GA.js. Was used to distinguish between new sessions and visits at the end of a session.
End of session (browser)
__utmz
Contains information about the traffic source or campaign that directed user to the website. The cookie is set when the GA.js javascript is loaded and updated when data is sent to the Google Anaytics server
6 months after last activity
__utmv
Contains custom information set by the web developer via the _setCustomVar method in Google Analytics. This cookie is updated every time new data is sent to the Google Analytics server.
2 years after last activity
__utmx
Used to determine whether a user is included in an A / B or Multivariate test.
18 months
_ga
ID used to identify users
2 years
_gali
Used by Google Analytics to determine which links on a page are being clicked
30 seconds
_ga_
ID used to identify users
2 years
_gid
ID used to identify users for 24 hours after last activity
24 hours
_gat
Used to monitor number of Google Analytics server requests when using Google Tag Manager
1 minute
You can find more information in our Cookie Policy and .
