Every off-grid build eventually hits the same wall. The fix isn't a bigger battery you can never fully recharge — it's a second and third way to make electricity that don't depend on a clear sky.
Small wind: the honest numbers
Wind's appeal is obvious — it blows hardest in exactly the weather that flattens solar output, and it runs at night. The reality is harsher than the marketing.
Power available from wind scales with the cube of wind speed. Double the wind, eight times the power. That single fact explains everything about small wind: a turbine rated "400W" is rated at a wind speed most sites rarely see. At half that speed it produces about an eighth of the rating. Most small turbines also have a cut-in speed of roughly 6–9 mph — below that, they generate nothing at all while still sitting there looking productive.
- Height matters more than the turbine. Wind speed increases substantially with elevation above ground clutter. A turbine on a short pole beside a trailer sits in turbulent, slow air and will disappoint you. Real installations use real towers.
- Turbulence is the enemy. Air tumbling over trees, buildings, or your own rig kills output and beats the bearings to death.
- You need a diversion (dump) load. Unlike solar, a wind turbine cannot simply be disconnected when the battery is full — with no load, many designs freewheel and destroy themselves. A diversion controller dumps excess into a resistive load (often a water heater element). This is not optional equipment.
- Noise and vibration are real. Anything mounted to your living space transmits into it. This is the complaint that makes people take them down.
Micro-hydro: the only source that runs 24/7
If you have year-round moving water with some drop to it, micro-hydro is the best-kept secret in off-grid power. A small stream producing a modest, unglamorous 100 watts continuously delivers 2.4 kWh per day — which quietly beats a substantial solar array, because it never stops for night or weather.
Output comes from two things multiplied: head (vertical drop) and flow (volume per minute). High head with low flow works. High flow with low head works. Neither alone does. Measure both honestly before buying anything — head with a level and tape, flow by timing how long a stream fills a known bucket.
- Intake screening is the whole game. Leaves, silt, and ice will clog you constantly. A well-built, self-clearing intake is the difference between a power source and a weekly chore.
- Penstock (pipe) sizing matters. Too narrow and friction eats the head you worked to get.
- Water rights and permits are real. Diverting a watercourse is regulated in most places, even on your own land. Check before you dig.
- Freeze protection determines whether it's a year-round system or a seasonal one.
Alternator / DC-DC charging: the one almost everyone should have
If your rig has an engine, you already own a generator — you're just not using it. A DC-DC charger takes power from the vehicle's alternator and charges your house bank correctly and safely while you drive. For anyone who moves regularly, this is often the highest-value charging upgrade available, and it works in weather that gives solar nothing.
If you run a Jackery station rather than a DIY bank, they make a DC-DC alternator charger built for their units — same principle, matched to the hardware.
Size it to your alternator, not your ambition — a common rule is to stay well under half the alternator's rating for continuous draw, and to check whether your vehicle uses a smart/variable-voltage alternator, which changes the requirements.
Fuel generators: honest backup, not a lifestyle
A generator is the bluntest tool in the box and sometimes exactly the right one. Modern inverter generators are quiet, fuel-efficient, and produce clean power safe for electronics. The trap is buying one too big: an oversized generator running a small load burns fuel inefficiently and wet-stacks (unburned fuel fouling the exhaust) on diesel units.
The efficient pattern is generator → charger → battery bank → your loads, running the generator hard for a short window to bulk-charge, rather than idling it all day to run a laptop. And read the CO section on the Safety page before you run one anywhere near an enclosed space — generators kill people every year.
Combining sources without them fighting
A hybrid system is where this gets genuinely engineering-flavored. The core principle: every charge source must agree about the battery. They all need charge profiles matched to your chemistry and voltage, and they must not fight over who is charging.
- Each source gets its own properly-rated controller — an MPPT for solar, a diversion controller for wind/hydro, a DC-DC for the alternator. They connect to the bank, not to each other.
- A battery monitor / shunt is what makes a multi-source system legible. Without it you're guessing about what's coming in and going out.
- Set consistent voltage set-points across every charger. Mismatched absorption voltages cause chronic under- or over-charging that quietly ages the bank.
- Wind and hydro need somewhere for power to go when the bank is full. Solar can simply stop; they usually cannot.
Whatever mix you choose, the daily energy budget is the same math. Run it through the Power Sizer first — generation supplements a correctly-sized system; it doesn't rescue an undersized one.