Solar Photovoltaic Array

Silent, no moving parts, and the fuel falls on you for free.

Why it is worth it

Panels turn daylight straight into DC electricity with nothing to wear out. For most homesteads solar is the backbone: pair it with a battery bank and you have power day and night. Size the array to your daily load (see 1.23), aim it toward the equator at roughly your latitude, and keep it clear of shade.

Materials & tools

• PV panels
• Racking / mounts
• Charge controller (MPPT)
• Fused DC combiner + disconnect
• Correctly sized PV wire
• Grounding lug + rod

Step by step

1. Size the array from your daily watt-hour budget and local sun-hours.
2. Mount facing the equator, tilted near your latitude, in full all-day sun.
3. Wire panels in series/parallel to hit the controller's voltage window.
4. Run through a fused DC disconnect to the charge controller, then to the battery.
5. Ground the frames and system per code; add surge protection.

Solar Tracking Mount

Follow the sun and wring more hours out of the same panels.

Why it is worth it

A fixed panel only faces the sun squarely for an hour or two. A tracker pivots the array to follow it, adding 25 to 45 percent more daily energy, most of it in the valuable morning and evening. A single-axis tracker follows east-to-west; dual-axis also adjusts for the seasonal height of the sun.

Step by step

1. Build a balanced pivot frame that carries the array's weight and wind load.
2. Drive it with a linear actuator (active) or a passive gas-charged tracker.
3. Control with a light-seeking sensor or a timed program.
4. Set wind-stow limits so storms lay it flat.

Horizontal-Axis Wind Turbine

When the sun is down and the wind is up, the propeller keeps the lights on.

Why it is worth it

Wind complements solar beautifully: it often blows hardest in winter and at night when the panels are idle. A propeller-style (horizontal-axis) turbine on a tall tower is the most efficient wind machine. The two hard truths: you need real, steady wind, and you need the turbine up high and clear of trees and buildings (turbulence near the ground wrecks output and bearings).

Materials & tools

• Turbine + blades
• Tall tower + guy wires + anchors
• Rectifier (if 3-phase)
• Charge controller with DUMP LOAD
• Slip ring or droop cable
• Disconnect / brake

Step by step

1. Confirm your site's average wind; measure if you can.
2. Raise the rotor at least 30 ft above anything within ~500 ft.
3. Guy the tower properly to rated anchors; plan a safe raise/lower (tilt-up).
4. Rectify AC to DC if needed, into a controller with a dump load.
5. Fit a shut-down brake or short for storms and service.

Vertical-Axis Wind Turbine

Takes wind from any direction, lives closer to the ground, shrugs off gusts.

Why it is worth it

Vertical-axis turbines spin on an upright shaft, so they do not need to turn into the wind and they tolerate gusty, turbulent, swirling wind better than a propeller. A drag-type Savonius self-starts in light wind and is easy to build from barrels; a lift-type Darrieus is faster but needs help starting. They are less efficient than a good HAWT but simpler, quieter, and friendlier near buildings.

Step by step

1. Pick the type: Savonius for easy DIY and low wind, Darrieus for more output.
2. Build a balanced rotor on a sturdy vertical shaft and bearings.
3. Couple to a low-RPM generator (often a modified motor or axial-flux).
4. Rectify to DC into a controller with a dump load, same as any wind machine.

Overshot Water Wheel

If you have falling water, you have the steadiest power on the homestead.

Why it is worth it

A stream with a modest drop can run 24 hours a day, rain or shine, wind or calm, which makes micro-hydro the most reliable off-grid source of all where it is available. The classic overshot wheel takes water onto the top of the wheel and lets gravity in the filled buckets turn it; it suits low flow with moderate head (a few feet of drop).

Step by step

1. Measure your head (vertical drop) and flow (gallons per minute).
2. Build a flume to deliver water onto the top of the wheel.
3. Size the wheel so filled buckets on the descending side drive it.
4. Gear up the slow wheel to a generator's RPM via belt or chain.
5. Return the water to the stream (tailrace) below.

Pelton Wheel (High Head)

A tall pipe of water, a nozzle, and a spinning cup wheel: big power from a small stream.

Why it is worth it

When you have head (a lot of vertical drop) but not much flow (a hillside spring or creek), a Pelton wheel shines. Water piped down a penstock gains pressure and is fired through a nozzle as a fast jet onto spoon-shaped cups, spinning a small wheel fast enough to drive a generator directly. More head means more power from the same trickle.

Step by step

1. Find high head: measure the vertical drop from intake to turbine.
2. Run a penstock pipe down the drop (bigger pipe loses less pressure).
3. Fire the jet through a sized nozzle at the Pelton cups.
4. Couple the wheel to an alternator, into a rectifier and controller.
5. Return water to the stream below.

Cross-Flow (Banki) Turbine

The workhorse for streams with more flow and less drop.

Why it is worth it

Where a Pelton wants head and a wheel wants gentle flow, the cross-flow turbine sits in between: a wide rectangular jet pours across a drum-shaped rotor (the water passes through the blades twice), handling bigger, lower-head flows gracefully. It is forgiving, self-cleaning, and buildable in a farm shop.

Step by step

1. Match the turbine to your head-and-flow pair.
2. Build the drum rotor and the rectangular guide-vane nozzle.
3. Feed from a penstock or open flume into the nozzle.
4. Belt to a generator; rectify and control as usual.

Archimedes Screw (Very Low Head)

Barely any drop at all? An old spiral still makes power, and fish swim through it.

Why it is worth it

With only a foot or two of drop but good flow, run the Archimedes screw in reverse: falling water turns the spiral instead of the spiral lifting water. It works at tiny head, tolerates debris, and is famously fish-friendly, which matters where screened intakes and fish passage are required.

Step by step

1. Set a large spiral screw on a shallow incline in the channel.
2. Let falling water fill the flights and turn the screw.
3. Gear the slow, high-torque shaft up to a generator.

Thermoelectric Generator (Wood-Stove TEG)

Turn the heat you are already making into a trickle of electricity.

Why it is worth it

A thermoelectric module makes DC from a temperature difference across it. Clamp one to a hot wood stove with a cooled heat sink on the other side and it quietly produces a few watts all winter, exactly when solar is weakest, enough to charge phones, run LEDs, or trickle a small battery. No moving parts.

Step by step

1. Mount a TEG module flat against a hot stove surface (within its rated temperature).
2. Clamp a finned heat sink (air or water cooled) on the cold side; the bigger the difference, the more power.
3. Feed the output through a DC-DC regulator into a small battery.

Pedal / Bicycle Generator

Your legs are a generator that also keeps you warm.

Why it is worth it

A human can sustain roughly 75 to 150 watts of pedaling. That will not run a house, but it will charge a phone, power lights and radio, or top a small battery when the sun and wind both quit, and it works any time you are willing to work for it. Simple, cheap, and good exercise.

Step by step

1. Mount a bike on a stand so the rear wheel drives a motor-used-as-generator (friction roller or belt).
2. Rectify the output and run it through a DC-DC regulator into a battery.
3. Add a meter so you can see your watts.

Wood-Gas (Gasifier) Generator

Run an engine on smoke: turn wood into a gas you can burn.

Why it is worth it

A gasifier starves wood of oxygen and heats it until it gives off a combustible producer gas (mostly carbon monoxide and hydrogen) that an ordinary engine can run on. In a fuel emergency it lets a woodlot power a generator. It is also the most dangerous project in this chapter and belongs only in experienced hands.

Step by step

1. Build the stages: fuel hopper, restricted reduction zone, then cyclone, cooler, and filter to clean the gas.
2. Pipe the cleaned, cooled gas to the engine's air intake.
3. Start on gasoline, then switch to wood gas once the gas runs clean.
4. Run only in the open air, never enclosed.

Biogas Generator

Rot turns manure and scraps into cooking gas and electricity.

Why it is worth it

An anaerobic digester (Chapter 6) feeds on manure and food waste and gives off methane-rich biogas. Scrubbed of hydrogen sulfide and moisture, that gas cooks, heats, and runs a converted engine-generator, all from waste you already have. It shines in warm climates where the digester stays active.

Step by step

1. Build and feed the digester (see Chapter 6) and let it establish.
2. Scrub the gas (iron sponge for H2S, a moisture trap for water).
3. Feed the clean gas to a converted spark-ignition engine driving a generator.

Fuel Generator Backup

The thing you run as little as possible, and are very glad to have.

Why it is worth it

A gas, propane, or diesel generator is the backstop for the dark, windless week when the batteries sag. Used right, it runs briefly to bulk-charge the bank or carry a heavy load, then shuts off. Propane stores for years without going stale, which makes it the off-grid favorite.

Step by step

1. Size it to your charger/largest load, not your whole future.
2. Wire it to the system through a proper transfer switch or interlock.
3. Feed a battery charger so short runtime does the most good.
4. Run it outdoors, well clear of windows and intakes.

Flooded Lead-Acid Battery Bank

Heavy, cheap, proven, and forgiving if you tend it.

Why it is worth it

Flooded lead-acid (the golf-cart or L16 battery) is the old reliable of off-grid storage: cheap per watt-hour, tolerant of abuse, and repairable. The trade is maintenance (checking and topping water) and that it should not be drawn below about half charge if you want it to last years.

Step by step

1. Wire cells in series/parallel to your system voltage and capacity.
2. Use proper cable, a main fuse, and a bus bar; torque terminals.
3. Set the charge profile (bulk, absorb, float, periodic equalize).
4. Check electrolyte monthly and top with distilled water.

AGM & Sealed Lead-Acid

Lead-acid with the maintenance and the venting mostly designed out.

Why it is worth it

AGM (absorbed glass mat) and gel batteries hold their acid in a mat or gel, so there is no watering, far less off-gassing, and they can be mounted in more positions. They cost more than flooded cells and are less tolerant of overcharging, but they are the easy, low-fuss lead-acid choice.

Step by step

1. Wire to voltage/capacity with proper cable and a main fuse.
2. Set the charge profile to the AGM spec (they dislike the high equalize voltages flooded cells want).
3. Add a temperature sensor so charging compensates for cold and heat.

LiFePO4 Lithium Bank

Light, deep-cycling, long-lived: the modern off-grid battery.

Why it is worth it

Lithium iron phosphate holds far more usable energy per pound, can be drawn down deep without harm, lasts thousands of cycles, and needs no watering. It costs more up front but often less per usable cycle, and LiFePO4 is the safest lithium chemistry (it does not readily run away like the laptop kind).

Step by step

1. Build the pack to voltage with matched cells and a proper Battery Management System (BMS).
2. Let the BMS handle cell balancing and cutoffs; wire balance leads correctly.
3. Set the charger to the LiFePO4 profile (no float abuse, correct voltages).
4. Fuse and protect as with any bank.

Nickel-Iron (Edison) Cells

Nearly immortal batteries you can abuse for decades.

Why it is worth it

Edison's nickel-iron cells can last 50 years or more, shrug off being left discharged, overcharged, or frozen, and are rebuildable by swapping the alkaline electrolyte. The price is low efficiency, high self-discharge, and a big up-front cost. For someone who wants a battery their grandchildren inherit, nothing else compares.

Step by step

1. Series the cells to system voltage (each cell is ~1.2 V).
2. Fill with the specified alkaline (potassium hydroxide) electrolyte.
3. Charge at the higher voltages NiFe wants; expect lots of gassing.
4. Top electrolyte and change it every several years.

Micro Pumped-Hydro Storage

Store surplus power as water uphill, spend it as water downhill.

Why it is worth it

If you have two ponds at different heights, surplus solar can pump water up by day; at night that water runs back down through a turbine (1.6/1.7) to make power. It is the oldest grid-storage trick, scaled to a homestead: no battery chemistry to wear out, just water and head. It needs real elevation and volume to store much.

Step by step

1. Establish an upper and lower reservoir with as much head between them as you can.
2. Use a pump to lift water with surplus power.
3. Return it through a turbine when you need power.

Thermal Storage (Hot Water / Mass)

The cheapest battery for heat is heat itself.

Why it is worth it

You do not have to store every surplus watt in an expensive battery. Divert midday solar excess into an immersion element in a well-insulated water tank, or into a mass of rock or cob, and you bank cheap heat for the evening: hot water and warmth without chemistry. It is the best use of power you would otherwise dump.

Step by step

1. Set the charge controller to divert excess (instead of a dump resistor) into a water-heater element.
2. Store the heat in a well-insulated tank or a thermal mass.
3. Draw the heat in the evening.

Charge Controllers: PWM vs MPPT

The brain between the panels and the battery. Pick the right one.

Why it is worth it

A charge controller stops your source from cooking the battery and manages the charge stages. A cheap PWM controller simply connects panel to battery and works when their voltages are close. An MPPT controller is a smart DC-DC converter that harvests the panel's maximum power and down-converts the voltage, gaining 10 to 30 percent, especially in cold and with higher-voltage arrays. For anything but the smallest system, MPPT pays for itself.

Inverters: Modified vs Pure Sine

The box that turns your battery's DC into household AC.

Why it is worth it

Most appliances want AC, so an inverter converts your battery DC to 120/240 V AC. A cheap modified sine inverter runs resistive loads and tools fine but can buzz, overheat, or refuse sensitive electronics, motors, and chargers. A pure sine inverter makes clean, grid-quality power that runs everything. For a whole-home system, buy pure sine.

The Whole System: Fusing & Grounding

How it all ties together, safely. This page is the one to get right.

The rules that keep it from burning down

• Fuse every ungrounded conductor close to its source (array, battery, each branch). A battery can deliver thousands of amps into a fault.
• Size wire to the current and the distance; undersized wire is a fire.
• Use DC-rated disconnects at the array and battery so you can isolate for service.
• Ground and bond panel frames, equipment, and the system per code, with a ground rod and surge protection.
• One bonding point between neutral and ground; know where it is.

Sizing It: The Load Budget

Everything upstream is sized by one honest worksheet.

Do this before you buy anything

List every load, its watts, and the hours per day you run it; watts times hours is watt-hours. Add them for your daily watt-hour need. That one number sizes everything: divide by your local winter sun-hours to size the array, and multiply by your days-of-autonomy and depth-of-discharge to size the battery bank.

1. List loads: lights, fridge, pump, tools, phone, well pump.
2. Watts x hours/day = Wh for each; sum them.
3. Array watts ≈ daily Wh ÷ winter sun-hours (add ~25% for losses).
4. Battery Wh ≈ daily Wh x days of autonomy ÷ usable depth-of-discharge.