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24 October 2003

1) Website changes
2) Using an inverter
3) Portable solar panel
4) Ideas please

1. Website Changes

Now the autumn has really started here in mid-Wales it's given me an opportunity to do some much needed site maintenance. There are no great changes, but I've updated the links page to get rid of any broken links and added an exciting new mail order equipment supplier.

The equipment page has also changed. I was never really happy with it so I've taken the pictures away and made it easier to understand.

Check it out at

2. Using an Inverter

I had an e-mail a while ago from someone asking how much power an inverter uses. It's a question I get asked a lot, and there's no simple answer.

Of course there is an answer to the question, but it's another question: 'How much power are you going to use?'

Here's how you work out how much power an inverter uses, and ultimately what its energy requirement is:

- List all the things you are going to power from the inverter.
- List the power consumption of each item.
- Go through the list and add up the maximum likely power consumption at any one time by deciding what things will be on at the same time. Multiply by 1.2 to give a 20% safety factor and that's the continuous power rating of your inverter.

- Find out the inverter efficiency. Ask the manufacturer or, if you can't find out, assume it's 80%
- Divide the power consumption of each item by the efficiency of the inverter, e.g. if it's 80% then divide by 0.8 to give a bigger number. Use these numbers to size the system in the normal way.
- If the inverter will be on for extended periods without a load, consider the no-load power consumption of the inverter as another DC load.

Simple really.

3. Portable Solar Panel

I've been sent details of a lovely little portable solar panel. It has a peak output of 13 Watts and a nominal voltage of 12 Volts. It folds up into a briefcase shape with a carrying handle and I reckon it would be ideal for people who need to charge batteries in the middle of nowhere. Check it out at link obsolete

4. Ideas Please

I'll be starting work on a new e-book soon. It will be a comprehensive guide to designing a solar power system which follows on from the introduction given by the free book.

If you have any ideas about what should go into it, questions you'd like to see answered and that sort of thing then please let me know at:

mailto:[email protected]

All suggestions gratefully received.

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