Here is a good summary and idea for all 220 volt AC, or 110 for us:

“Cost of solar cells, on their own, is about 3-6 $/watt. A single 150w cell is 450$ or so. Ten are 4500$. You need a charger ie electronic controller (500-1000), cables (500-1000) and appropriate batteries (10x8D).

The cable MUST be thick, as its DC, thats why they are not cheap. The cheapest marine deep-cycle batteries or AGMs are about 400-500$ each. 10 x 450$=4500$.

Total cost is about 12-14.000$ if you install everything yourself, and buy everything at rock-bottom prices. The work will be about 100 hours. Now, for me, myself, this is exactly what I will buy/install. And I plan to spend, if I must, about 15.000$ at it. I suspect that in 1-2 years the system cost will be about half, as batteries are getting cheaper and so are the solar cells.

Because I want to have house loads available for 5 days without running a generator. This needs about 10-15 solar cells of about 150w nominal, for about 1000w real continuous power. It needs about 12-15 square meters of area. I will put mine on the pilothouse roof. The 2000w nominal gives you grid independence, You can live with a fridge and pc almost not running a generator/motor.

And I will have 220v, 50hz throughout, nothing and I mean nothing will run on DC. It far cheaper, far more reliable, less corrosive, more efficient etc. etc. etc. Cable losses account for about 20% of your consumption in DC and under 1% in AC 220v. Because you first have to generate the DC, you first lose 20% then lose
is again when using it. So, you are wasting about 40% of your electricity in heating the cable with DC! DC cables cost about 4-5 times more than ac (as they must be thicker). Also, all appliances and tools are far more reliable when meant for industrial and house use and running at 220 V, 50hz. For example, a house freshwater (pressure) pump will run 10-20 years and costs under 1000$. Same for cooking etc. etc. An energy efficient house refrigerator will be about the same efficiency as the best DC system you can have custom built. It costs 500$ vs about $5000 for the best custom stuff. Its about 5-10x more reliable, and you can buy a new fridge anywhere in the world for $500. You can make/build a custom enclosure if you want. Wood, granite, stainless, whatever. I will. Just make sure its easy to disassemble (don’t glue the pieces). All of the above is based on a live aboard, like a trawler yacht, with standard house conveniences like fridge, shower pressure water, pc or laptop etc.”

Power Needs Inventory


Air Compressor 5 HP, 18.1 CFM @ 90 PSI 230 30 6,900
Plasma Cutter – Hypertherm Powermax1000 230 44 10,120
Plasma Table 110 10 1,100
  AC Peek Watts 18,120
Welder (V300 Inverter) 240 43 10,320
ROV Plasma Monitors
Washing Machine
Ice Maker – Edgestar, 28 pounds/day 115 3.48 400
Water Maker


Controlling the speed of a brushed DC motor is simple. The higher the armature voltage, the faster the rotation. This relationship is linear to the motor’s maximum speed.
The maximum armature voltage which corresponds to a motor’s rated speed (these motors are usually given a rated speed and a maximum speed, such as 1750/2000 rpm) are available in certain standard voltages, which roughly increase in conjuntion with horsepower. Thus, the smallest industrial motors are rated 90 VDC and 180 VDC. Larger units are rated at 250 VDC and sometimes higher.

Specialty motors for use in mobile applications are rated 12, 24, or 48 VDC. Other tiny motors may be rated 5 VDC.

Most industrial DC motors will operate reliably over a speed range of about 20:1 — down to about 5-7% of base speed. This is much better performance than the comparible AC motor. This is partly due to the simplicity of control, but is also partly due to the fact that most industrial DC motors are designed with variable speed operation in mind, and have added heat dissipation features which allow lower operating speeds.

Easy to control torque

In a brushed DC motor, torque control is also simple, since output torque is proportional to current. If you limit the current, you have just limited the torque which the motor can achieve. This makes this motor ideal for delicate applications such as textile manufacturing. —


An inverter converts DC to AC. There is approx. a 5 to 10% energy loss converting from DC into AC.


A rectifier converts AC to DC.

DC to DC converter

A DC to DC converter steps down DC voltage, for example from say 120v to 12v.

Battery Chargers

Forklift battery chargers come in both 1 and 3 phase with common outputs of 12, 24, 36 and 48 volts. A 48 VDC, 153 Amp output charger can be purchased used for about $300.

Generator Heads

Chinese made generator heads are available on eBay from Bill Osborne,, in Milledgeville, GA.  The 20KW 3 phase is $570 and 30KW 3 phase 120/240 is $980. (Feb 2009) Both heads need to turn at 1800 RPM, the 20KW  head requires 29 HP and 30KW head requires 43  HP.

“Depending on what engine you use, you can use an electronic governor or have to go with a mechanical. Some guys use a lister engine (old style diesel) with a mechanical and works very well. Others go on the high end and use a big engine and use an electronic one. Some things to know about this when setting up: get a Kill-A-Watt meter and use it to set the frequency to 62Hz (equates to 1860RPM) under no load. This way when the unit is at max load, the frequency will go down to about 58-59Hz. Any item in a house can use this and will not hurt anything.” –Bill

Wind Generator

Alternators – The biggest problem with using car alternators for wind power is that they are designed to rotate at too high a speed to be practical in wind power applications without significant modifications. Even a small, seemingly fast windmill might do most of its work at 600 rpm, not nearly fast enough for a car or truck alternator. This means that gearing up with pulleys or other methods is needed, so lots of power is lost to friction–a big problem with wind or water power, but not a problem with a gasoline engine.

Our experiments have consistantly shown that homemade PM alternators are the most powerful and cost-effective solution for building a wind generator. Their low-rpm performance is excellent, and at high speeds they can really crank out the amps thanks to their efficiency. Our more recent PM alternators have been based on Volvo disc brake assemblies, which are very sturdy and have thrust bearings built into the unit. Our larger units are “Disc” or “Axial” designs…a flat plate of magnets rotating next to a flat plate of coils. Our smaller PM alternators are “Radial” designs, where the magnets are fastened to the outside radius of the armature. Since all alternators produce AC, the output must be converted to DC with bridge rectifiers for battery charging.

Our designs to date have been single phase for ease of construction. Three-phase alternators have some advantages (they are somewhat more efficient, and make better use of available space), but they are somewhat more difficult to build.

With a 7 ft diameter prop, (Wind) our Volvo brake designs can put more than 60 amps into a 12 volt battery in a 30-mph breeze–that’s about 700 watts. We’ve seen the Volvo design peak at over 100 amps during high winds! This gives these homebrew designs a big advantage over similar-sized converted induction motors, which become inefficent quickly and top out at 20-25 amps output with a 7 ft. diameter prop.   —

Low-RPM Disk Alternator

Axial flux windmill plans —

Low Cost – Tread Mill Motor


Auto Pilots

LED Lighting

…parallel them and use however many you want. Please note that you
shouldn’t just parallel the LEDs themselves, since the slightly-variant
voltage drop across them would just cause them to burn out one after
another; instead, connect each LED in series with the appropriate
resistor (i.e., max current of 20mA at max voltage – say, 14.4v while
you’re running your engine – works out to (14.4-3.2)/.020=560 ohms),
then parallel all your LED/resistor sets, as many as you’d like:

______     ______
+12v |     |
z     z
z 560 z 560
z     z
|     |
_     _
Gnd  |     |
—— —— …

Also, I wouldn’t rely on just the regulator to block spikes; their
response time isn’t all that good. Put a couple of capacitors – say, a
.001µF and a 1µF tantalum with at least a 50V rating – across the
regulator input; that should protect both it and the LEDs.  –Ben Okopnik