Off-Grid Solar Systems: Load Lists, Battery Banks, Panel Sizing, Cables & Monthly Energy Balance

What you'll build

What you will be able to do

Each lab ends with a concrete result that you build yourself and the checker confirms, cell by cell.

• Turn a cabin's load list into Wh per day, add the inverter loss for the AC loads and a planning margin, and find the largest start-up surge the inverter has to cover.
• Choose the system voltage of five projects with IFS, convert daily Wh into battery Ah and compare the peak currents with what the same loads would draw on 12 V.
• Size Fernbrook's battery bank from the design energy, days of autonomy, usable depth of discharge and efficiency, then turn the Ah into strings and battery units.
• Size the array for the design month, round up to whole panels and check how many panels fit in series before the cold-weather voltage passes the controller's input limit.
• Size the charge controller's output current with a margin, pick the next rating up from a model list and compare the daily yield of a PWM and an MPPT controller.
• Compare solar yield and load month by month, turn the daily balance into kWh per month, add up the generator hours needed in the deficit months and chart the year.
• Calculate the minimum cable cross-section of five DC circuits from current, length and allowed voltage drop, pick standard sizes, check the actual drop and look up a fuse size from a fictional table.
• Price the system, calculate its cost per kWh over the life, and compare it with running a generator through simple payback and a net present value.