Solar Electricity

[MikeBoxwell]

I've written a book on how to use solar panels to generate electricity. It feels very strange to see my name on the cover of a book!

The real reason for writing this thread though is that there the publishers have put up a web site that accompanies the book that includes some pretty impressive solar calculators. If you're interested in finding out more about solar power, they're worth a look at - I certainly haven't found anything better on the web (although please let me know if you think they can be improved).

Some of these tools are also useful for people looking at solar hot water systems - especially the solar angle calculator and the solar insolation calculator which will tell you how to position the panels in the optimum position and how to calculate how much energy you can expect to get from your system for every month of the year.

Solar Calculator - solar analysis reports, solar irradiance calculators and solar angle calculators

[Phil]

Thanks for the link - the calculators come in handy. I'm considering between adding solar heaters and/or a wind turbine to my 4th floor flat in London. Got to weight up the benefits of money saved/feel-good-factor against the potential loss of roof terrace space which is a very sought after feature in this town.

[MikeBoxwell]

You need to be very careful with your calculations for wind. Wind turbines like a nice smooth airflow, and you are unlikely to get that in the middle of London. Turbulent air means you end up with very little power generation at all.

Of course, you can get around that by oiking the whole thing up on the end of a long pole, 20 metres up in the air, but then you start getting neighbours complaining...

[Phil]

Yeah, my dad's had the same problem installing a wind turbine into his garden in Scotland. Has trouble getting the turbine up to 'generating speed', and when it does, kicking in the dynamo causes it to slow down and therefore drop it back below optimal speed.

My flat in London is the tallest building around, and it is a constant wind, however I still think it'd be a bit futile. At least with solar water, there's an easy option for storage of the power (i.e. in the hot water). Only problem is though, I like my terrace space, and we don't actually have a water tank.

The final option is PV solar cells, but are they even any good in this country (in comparison to the wind potential)?

[Mike]

Congratulations on the Book Mike! that really is excellent :)

Dont forget to submit it to the directory too!

[MikeBoxwell]

Originally Posted by Phil

The final option is PV solar cells, but are they even any good in this country (in comparison to the wind potential)?

It depends on what you want to do with it. If you want to be able to disconnect your house from the national grid and run purely on solar power, you're going to struggle. If you want to use solar electricity for very a specific purpose, then you could well be able to do it.

A good example would be lighting. So long as you are using low wattage lightbulbs throughout your house, there is no reason why you couldn't run all your lighting on a solar based system.

The real world benefit of doing that is that you have a secondary power source: if you lived in an area that had frequent power cuts, for instance, you could use your solar system as an emergency power source as well as powering your lights.

If you wanted to run your lights on solar power completely throughout the year, this set up would probably get quite expensive - simply because of the lack of sunshine during December and January - but if you were happy for a system to provide your complete needs for nine months of the year and supplement your solar system with mains power during the winter, you could build such a system for around £1,000.

Is that worthwhile? Quite frankly, in the middle of London, I would suggest the answer is no. If you were in the middle of the sticks and had regular power cuts and needed a more reliable power supply, I would suggest that £1,000 is good value for money.

[NaturalChoices]

Last September I finally bit the bullet and had a 2.8 kiloWatt PV system installed, wasn't cheap but there is only so long you can go on living with candles and a generator.
In January our part of the world was hit with some incredible storms and two high tension pylons fell over. The whole are was cut off from the grid for a week. Ther only two houses with power was mine and my neighbour.
Boy did I feel smug.
Pete

[MikeBoxwell]

Wow! That's an impressive setup. It's a testimony to your setup and your prudent use of electricity that your system managed to provide you with all your electricity needs in January - when solar insolation figures are very low.

More and more people are now deciding that solar energy is cost justifiable for a home installation: for the cost of a new family car you can now generate your own electricity for life.

[Andy]

Has pv technology moved on a lot recently?

We enquired a while ago and both the cost and the technology proved to be probibitive

[MikeBoxwell]

Prices have dropped a little recently - it's dropped by around 5% over the past three months.

As to whether it works for you, it really depends what you want to do with it. If you decide you want to run your house or charge up an electric car on solar power, it's going to cost you an awful lot, and it will take 25 years plus to pay for itself.

Solar works best for small, stand alone projects where you want to generate a modest amount of electricity for a specific purpose. If your daily power requirement can be measured in tens of watts rather than kilowatts, solar can be very cost effective.

An excellent example would be if you wanted electricity in a garden shed, a lock up garage, or on a shed at an allotment, so that you could run a couple of lights, a radio, charge up a few power tools and run a lightweight strimmer from time to time. In this scenario, it may be difficult - or even impossible - to install a mains electricity connection, but you could install a solar panel, battery, controller and inverter (if necessary) and do the job for quite reasonable amounts of money.

How reasonable is reasonable? Well, just for a shed light you can have a decent system for around £30-50. To do all of what I suggested above would probably cost around £200-300 depending on how much you'd actually be using it.