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Solar Generator

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Portable Solar Generator

Generating energy independent from the main power grid is a key stepping stone to energy independence.

The original idea for my generator came from a Californian who, in 1996 built his own prototype. I'll be mentioning him at the end in the links section so be sure to take a look if you're interested.

This topic will discuss and show how you can, in a limited way, have a means of storing energy and re-charging it using sunlight.
It will also use easily available technology and requires only a basic understanding of electricity.

The unit, when complete will weigh about ten kilo's and be portable enough to lug around without too much difficulty.
It makes an excellent tool for living off-the-grid, in a shelter, in an RV vehicle and so on.
Should the power go out in your house one of these will soon get the lights back on!

You will need for this project:

A battery box capable of fitting a 12 volt car battery. Look for one with a tie-down strap like that pictured. Otherwise use bungees to keep it shut.

A deep-cycle battery of around 80 to 115 Ampere Hours (or Amp Hours for short).
However getting one in the dimensions of the widely available battery boxes out there won't be easy.

For this project I've chosen an 85 Amp Hours Deep Cell Battery. This will fit in a 12v car battery box you can get online.

A solar panel, or a set of solar panels linked up to the battery.

An Inverter (DC to AC)

A DC Output Box

Some wood measuring the panels dimensions.

A multimeter

A wire stripper

Optional extra's:

A voltage gauge

A switch to isolate the unit

The Battery you choose

Deep Cell Acid or Gel?

BatteryThe best battery type is either the tried and tested lead/acid type or gel-type.

The lead acid has longevity and is easy to maintain. Buying one of these with a big Amp Hour rating will give you many years of use if used correctly and maintained.
However it uses highly potent sulphuric acid and if you buy the battery 'dry' you'll need to manually add the acid to the battery's 6 cells correctly.
Also you need to ensure it doesn't slosh about too much as although sealed if the battery tips onto its side it could result in a spillage.
The acid is harmful to the skin.
A gel-type battery uses a chemical goo-like gel that does not leak out even in violent agitation. It's longevity isn't as long as lead/acid as they are sealed against tampering but in a marine environment they are ideal.

Once you've chosen what battery and box you are going for you'll need to get two things to get started.

Some heavy duty cord for lifting in/out the battery of the battery box and some electrode terminals for your wires.

Solartron Resources

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Solar panel set-up

Portability vs Power vs Hybrid

Big Solar PanelUnless you fancy re-charging your battery on a grid based charger you'll need a solar panel to help re-charge and keep the power topped up.
You have two choices to make here, or even a third depending on your approach:

Portability, Power or a hybrid?

Starting with the power option. This is a large, static panel system that ties into your battery via a quick-connect/disconnect set-up. For this you'd need to be somewhat more of an electrician and be good at installation.
Good areas for this include the roof of a house, a shelter and even an RV roof.
You'll also need to incorporate a charge controller so the battery doesn't accidently discarge through the array. Your cabling will also need to be quite thickly insulated too compared to.
More than one battery would be more than wise as if you're going to be running a house off one you'd soon drain a single 12v battery. So a handful of 12v battery's in parrallel would be needed.

Portability is what we're going for here though and much smaller panels that give less watts but allow it to be moved around from the home, to the car and so on.
However it is worth considering building a solar generator that does both portability and power via a system of quick-connect / quick-release connectors.
Alternatively you could have one for portability and one for power.

Solar Panel and assembly

Portable, light and easy

Portable Solar PanelFor the portable option I've chosen a small 5 Watt panel. This won't perform marvels but it's light and very cheap. They are also widely availably. Make sure you get one with attachment slots in each corner. These will make anchoring them onto wood and the like a lot easier.

Keeping everything as one complete unit I've mounted a rectangular piece of wood onto the battery box. Proper placement and accuracy here is important. Mount it at an angle and not so as to intrude with inverter on top. You can mount the inverter first but I find it's easier the other way round.

In the picture I'm at the stage of attaching the panel to the wood.

Solar Generator

Basic Unit Complete

SolartronI've used brass screw and nuts to secure the panel onto the wooden mount.
This is secure and can take some punishment.
The whole unit can be moved about and as long as its daylight the battery will be getting its precious energy topped up.
I don't have worry about disconnecting wires, packing up the loose bits etc.

Solar Generator Upgrading

Optional Extras

Solar Generator Volts GaugeWhile a multimeter can be used to take voltage readings I prefer the look and instant action of a voltage gauge.
Now finding a good one that is the right size can be difficult, but if you persevere you should locate one.
Make sure you find out the gauges dimensions otherwise it may be next to impossible to fit it inside.
For about $6 I have obtained the elusive voltmeter I've been looking for. This was sourced from the 3rd world but in the US or the UK they retail at about $15 to $25.
It might be work a look in a scrap-yard to see if you can get one out of a wrecked sports car or similar. This gauge is actually meant for a car.

Installing it was a bit tricky. I cut out a circle in the battery box and made sure the fit was extremely flush indeed. That way the gauge could be carefully squeezed through then environmentally sealed with silicon. Once it was wired in I inserted a small switch for power operation and lights on it.

Further Modification

DC Power Socket

Solar Battery CompleteTaking my project to the final stage of its design I now went about installing a means of running DC power from the solar generator.

The problem with using an Inverter is that, although it's ease of use allows household appliances to be plugged in, there are limitations.
Household appliances (due to the grid being AC) run off AC power and you're battery is Direct Current (or DC). This means you've got to use the inverter to run anything that's AC with it converted the DC to AC.

The battery has to have a hefty charge in it, it's a bit noisy (fan cooled) and it uses power to operate. This in tandem with the load you're running can mean it's not very long before the power dips below 10.5 volts which most inverters require to operate. Once that happens the device shuts down.

With DC Power socket wired in directly to the battery terminals you can plug in direct DC appliances and not have to worry about battery drain so much.
I've mounted this on top of the inverter and it's secured with adhesive glue and the battery strap.
Just at the bottom of the camera is a handy way to remotely turn on and activate the DC power to each socket.

Solar Panels and Off The Grid Videos

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