Home Solar Power

What would you say if I told you that you were effectively paying over $300 per KWh for your electricity?

Electricity is billed by all utility companies by the kilowatt-hour (kWh). If a single electric heater consumes 1 kilowatt ( 1000 watts) and the heater is left on for one hour then one kWh is used. Using a 60 watt light bulb for one hour consumes 0.06 kilowatt hours of electricity. Using a single 60 watt light bulb for one hundred hours consumes 6 kWh of electricity.

The average price of Electricity in the USA according to government statistics is 11.94 cents per KWh.

You may well be paying over $300 per KWh if you use disposable batteries in your flashlight, radio or camera.

The cost of a single AA batery is $1.47 at Walmart if purchased in a pack of 4. The average capacity of an alkaline battery is around 2900 mAh with a voltage of 1.5.

Since it’s a convention to measure energy in Joules, I’m going to convert the theoretical energy available in both cases. The battery, discharging to 0.8v a cells gives us 15390 Joules, or 15.39 KJoules of energy. Since 1 W/s is 1 Joule of energy, 1 kW hour = 60 x 60 = 3600 kJoules.

A single KWh of electricity therefore gives us 234 times the theoretical energy of a single AA battery. The actual energy obtained from the battery will be lower in practice since most devices stop working once the battery voltage drops to a pre-defined level, but I’m going to err on the side of caution in this analysis. Your battery power is therefore costing you $343 per KWh equivalent ($1.47 x 3600/15.39).

Luckily there is a solution to reduce these costs somewhat.

Rechargable batteries are widely available with around the same capacity of the disposable alkaline AA battery but these can be recharged up to 1,000 times. The average cost of four rechargeable batteries is $11. Even assuming they are only recharged 250 times, this brings the per usage cost down to a single penny. It’s true that you will need to use your relatively cheap mains electricity to recharge the batteries but, since this blog is about home solar power, there’s an even better solution. Amazon, and I’m sure many other stores, have a Home Solar Powered Battery Charger for less that $20:

So ditch those expensive polluting disposable batteries and go buy some rechargables.

Electricity Batteries, Electricity, Home Solar Power

As predicted, there’s no Toyota Electric Car in the works.

The official line from Toyota spokesperson Jana Hartline yesterday was “we’re not aware of any such vehicle, planned or otherwise.”

As you can see from the previous post it IS possible to power a car exclusively from solar electricity, but from panels mounted on the roof in suburbia? Not going to happen.

Solar Cars Add new tag, Solar Cars

An electric car has just completed an around the world trip covering 32,000 miles using only home solar power according to this post at Nashuatelegraph.

The car can travel at up to 55mph and has a range of 185 miles on a full charge.

Solar Cars Solar Cars

In order to generate usable electricity directly from sunlight we need to use commercially produced photo voltaic (PV) cells. These PV cells convert the light from the sun directly into usable electricity, albeit at a low voltage.

These PV cells are composed of two layers of semi-conducting material. When the sun shines on a PV cell it creates a voltage difference across the two layers of the cell. This voltage differential produces electricity which can then be stored in a battery for later use or used directly. The higher the light intensity, the greater the electric current flowing.  PV cells are linked together serially to provide a usable voltage.  Often they are produced in panels to provide sufficient power to charge a 12v lad-acid battery.

Are PV cells realistic for home home solar power?

Well… maybe!

PV cells and panels  are readily available and many companies will be happy to install you a working home solar power system. This will generate some electricity during the day, even when it’s cloudy. The problem is the cost of the installation. Typical installation prices are around $10,000 (USA) for a 2.5KWp system. This may generate half of your annual electricity if your location gets a lot of sunshine. Perhaps a third if you get some cloudy days. Even if we assume that you live in an area with very high electricity prices, this will save you at most $500 a year. This gives you a payback period of 20 years assuming no maintenance is required during the first 20 years. This is a realistic assumption for PV cells, barring physical damage. Battery technology, however, cannot provide this sort of no-maintenance or replacement time frame. Realistically, heavily used batteries will need to be replaced every five years or so increasing your maintenance costs.  If you live in an area with low energy costs, or a lot of cloud these figures are ever worse.

These high initial costs, and battery maintenance, must be reduced substantially for home home solar power electricity generation to be cost-effective. There are some DIY solutions than can be installed for as little as $200, which will reduce this payback period dramatically. I’m going to cover these low-cost home solar power projects in a later post.

Photo by Tiggs07

Electricity, Solar Power Electricity, Solar Power

China is planning to build a massive one gigawatt home solar power plant according to Greentech Media.

The plans are a little vague as to timelines but this would be almost double the size of the planned 550 megawatt home solar power plant to be built in San Luis Obispo CA.

Electricity Electricity

There’s a lot of talk about an electric car powered by PV cells on it’s roof being developed by Toyota. This story, first reported this week’s Nikkei newspaper, is variously described as both both nonsense and a technological breakthrough. Wired is now claiming that Toyota’s Solar Concept may not be a car at all.

Personally I don’t see that enough sunlight falls on the roof of a car, even assuming somebody could manufacture PV cells with 100% efficiency, to power a car for anything more than occassional use.

We shall see.

Solar Power Solar Cars

Proof that home solar power is reaching main street.  This home solar powered trash compactor was spotted in downtown San Antonio, Texas.

Photo by specialkrb

Solar Power Solar Power, Trash Compactor

First some obvious advantages:

It’s free.  Once you are set up there are no ongoing costs, whether it be used to generate electricity or for heating water.

It’s literally inexhaustible.  It will always be there in our lifetime.

It’s non-polluting with zero carbon emissions.  Good for reducing greenhouse gases and global warming!

It’s silent and has little visual impact.  No noisy generators, no ugly power stacks.

And, unfortunately, some disadvantages:

The initial costs may be high, especially for electricity generation.  It may need a long payback period, often several years, before the costs are recovered.

It doesn’t work well at night (duh!)

It isn’t as effective if you live in an climate where there is a lot of cloud cover, or in northern latitudes where the intensity of sunlight isn’t as high.

Obviously given the advantages and disadvantages of using residential home solar power are down to your unique and individual circumstances.  If you feel you can afford the substantial up-front investment and you live in a sunny climate home solar power make a lot of sense.  Living in the far north under a cover of cloud for 10 months of the year?  Not such a good idea.

Electricity, Hot Water, Solar Power Home Solar Power

All of life here on this planet is made possible by the light and heat from the sun. Without our sun, we would not be here. There is an unlimited supply of home solar power. It has been there for several billion year and should continue for many billion more. It causes absolutely zero pollution and creates no carbon-dioxide greenhouse gases.

The question I put to you is “why are we not all using this free unlimited source of energy?” We have all been spoiled by relatively cheap energy derived from fossil fuels such as oil, coal and gas. These are no longer as inexpensive as they once were and the carbon dioxide being release when we burn them in our power stations is undoubtedly leading to climate change.

Free solar energy has a number advantages over conventional fossil fuel sources of energy. The power from our sun is free and unlimited. Our only expense is that of collecting, using and storing this energy. These cost of recovery, whilst still high, are falling as new technology comes on line and it’s now becoming possible to generate much of the power for your own home from alternative energy sources, such as solar and wind power.

There are two main methods for recovering solar energy for the home:

Flat-Plate Hot-Water Collectors: These can allow every home to provide free hot water heated directly by the sun. They are relatively inexpensive to buy and install and have a payback time that makes these an economical prospect in sunnier climes. They are often composed of a number of copper pipes running through an enclosed sealed panel. They are mounted on a south or south-west-facing wall or roof and will provide hot water dring most of the year, even on cloudy days.

Solar Electricity Generators: These are photo voltaic cells which convert sunlight directly into usable electricity. These cells have become the world’s fastest-growing energy technology with production doubling every two years. This increase in manufacturing capacity has caused the prices of these cells to fall to a level that is affordable for use in home home solar power generation.

Electricity, Hot Water, Solar Power Climate Change, Electricity, Flat Plate Collectors, Global Warming, Home Solar Power, Hot Water