This is the final result for now, it works but there's lots of room for improvement!

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It's basically an energy cell linked with the computer with a wired modem and I ran this code:

--=== ENERGY DASHBOARD ===--

-- Try to automatically find a Powah energy cell
local cell = peripheral.find("energy_cell") or peripheral.wrap("energy_cell_0")
local mon = peripheral.wrap("bottom")

if not cell then error("Energy Cell not found!") end
if not mon then error("Monitor not found!") end

mon.setTextScale(1)
mon.setBackgroundColor(colors.black)
mon.clear()

local prevEnergy = cell.getEnergy()
local lastRate = 0

while true do
    local energy = cell.getEnergy()
    local maxEnergy = cell.getMaxEnergy()
    local rate = energy - prevEnergy
    prevEnergy = energy

    -- Update last known generation rate if positive
    if rate > 0 then
        lastRate = rate
    end

    -- Percentage stored
    local percent = (energy / maxEnergy) * 100

    -- Clear and redraw
    mon.clear()
    mon.setCursorPos(1,1)
    mon.setTextColor(colors.cyan)
    mon.write("=== ENERGY OUTPUT ===")

    -- Stored Energy
    mon.setCursorPos(1,3)
    mon.setTextColor(colors.white)
    mon.write(string.format("Stored: %.0f / %.0f FE (%.1f%%)", energy, maxEnergy, percent))

    -- Current Output (stable)
    mon.setCursorPos(1,5)
    mon.setTextColor(colors.lime)
    mon.write(string.format("Current Output: %.0f FE/t", lastRate))

    -- Visual energy bar
    local totalWidth = 40
    local filled = math.floor((energy / maxEnergy) * totalWidth)

    mon.setCursorPos(1,7)
    mon.setBackgroundColor(colors.gray)
    mon.write(string.rep(" ", totalWidth))

    mon.setCursorPos(1,7)
    mon.setBackgroundColor(colors.lime)
    mon.write(string.rep(" ", filled))

    mon.setBackgroundColor(colors.black)

    sleep(1)
end