The Solar Panel Project - Chapter 7: Practical ways to save energy


As mentioned on my intro page, if you want to get into renewable energy, only throwing large amounts of cash at a high quality installation will make any significant difference. It's the lifestyle changes that are more likely to make an impact rather than equipment installations such as this. For example, we recycle all materials accepted by the local waste disposal facility, avoid buying overpackaged goods, reuse what we can, we swapped the petrol-guzzling Range Rover for an efficient diesel VW Golf and made use of the employers flexitime policy to start work at 07:30-08:00 and leave around 16:00 thus avoiding the rush hour queues.

In terms of saving electricity, yes my installation will save some as several items have been taken off the grid, but energy (and money) can be saved without having to resort to complicated solar or wind power installations. Some basic measures anyone can undertake include:

Unplugging equipment that isn't in use;
Avoiding the use of 'powered art' - i.e. sets of lights that look pretty but serve no useful purpose;
Using hybrid rechargeable batteries instead of alkaline (disposable) batteries;
Converting all light fittings to run with CFL or LED bulbs;
Switching lights off when you leave the room;
Avoiding leaving TV's and computer monitors on standby for long periods;
Unplugging chargers once they have finished charging;
Using automotive chargers to charge items such as phones and MP3 players from your cars battery;
Hanging out washing to dry instead of using an electric dryer;
Taking showers instead of baths;
Turning down central heating thermostats or running the heating for shorter periods;
Investing in loft insulation and cavity wall insulation.

These are all common sense methods that are easy to apply and there are many others, you just have to look around you to see how you can apply such changes to your lifestyle. One example I can give is that we used to oven cook croissants every Saturday and Sunday for breakfast. This meant running our electric oven at 190C for several minutes every weekend. We cut this out and now have fruit instead which eliminates the need to run the oven, cuts out the non-recyclable packaging waste from the plastic used by the supermarket and we can compost the left over skin/cores etc. from the fruit. It's a simple change but it will make a big difference to the next electric bill and the size of our bin-bags.

It's worth taking a close look at your electricity bill to see how much you are being charged for your power. My supplier is Powergen and according to the bill I received for May to August 2007 my household used:

232kWh at 18.28p/unit (primary rate)
892kWh at 9.88p/unit (secondary rate)
449kWh at 4.24p/unit (night rate)

This makes a total of 1573kWh at a total of £149.58. My aim is to reduce this for the same quarter in 2008.

If you don't already know, kWh stands for kilowatt hour and represents 1000Watts of electricity over a period of one hour. To put it another way, if you had a 1000 Watt light bulb and left it on for one hour, it would use 1kWh.

We can divide a kilowatt by 1000 to find the cost of a single watt:

18.28
------- = 0.01828p per Watt (primary rate)
1000

Of course, nobody has a 1000 Watt light bulb - but you might have less. For example, I had 100 Watts of lighting split over four 25W bulbs in one small room so to run these lights for one hour at primary rate would cost:

100 x 0.01828 = 1.828p (just shy of 2p)

Doesn't sound like much does it? Only 2p to run my lights for an hour on primary rate! Still, it all adds up and if I did that every day for a year it would cost £6.67. It's possible to get the same light output from energy saving bulbs for less. I changed my 100 Watts of lighting to 20W using four 5W Compact Flourescent Lamp (CFL) bulbs giving me nearly the same light output but for a fifth of the power consumption. The same usage now costs:

20 x 0.01828 = 0.3656p (just over a third of a pence!)

Again, doing the same yearly calculation we get £1.33 as our annual bill - a saving of £5.34. Doesn't sound like a lot, but this is one example and of course, we all use much more electricity than 100 Watts for one hour per day.

The first thing I bought when undertaking this project was a power meter. Mine cost £13.60 (delivered) from an online auction site and they're also available from CPC.


Just plug it into the wall, plug the item to be tested into the meter and it will read off all kinds of interesting facts including Watts, Amps, VA, kWh consumption and the voltage/frequency of the AC input. It's great for seeing just how much power is being consumed and at what point. For example, my CRT iMac DV spikes at about 230W when firing up, stabilises at around 86W when sitting idle and continues to draw about 3W when switched off. Similarly, my CRT 21" TV with digibox takes about 80W when on, 9W when on standby and 6W when switched off. It just goes to show that switching off the mains sockets or unplugging items when not in use really does save power. These items alone, if not unplugged, consume enough power when switched off to run a 9W energy saving (CFL) light bulb - that's equivalent to nearly two of the 5W bulbs I just fitted!

Identifying and eliminating this kind of power wastage should be the first thing you do before trying to switch over to a renewable source.

The bottom line then - was it all worth it?
Well... yes. For me it was. It was an interesting project but I can see that it's not going to be practical for everyone. If you have a remote building without mains power then it's worth considering an installation such as this, but solar power around the home really needs much more of an investment than I can afford in order to be really worthwhile.

redundant_adaptors.jpg
A pile of mains adaptors that are no longer required. Some of these were plugged in 24/7 drawing constant power from the mains. Now they can go into a box and wait for the day that they are either put into useful employment somewhere else or pulled apart for spares.

 

Below is the list of fixed (i.e. non-portable) items converted to run off my solar installation. Power consumption readings were taken from the mains power meter before conversion.

Equipment: Power consumption when on:
Power consumption if off:
'On' time:
Nightlight 11W 0W Daily (10 hours)
Decorative LED lights (hall) 2W 2W 24/7
Decorative LED lights (landing) 2W 1W 24/7
Decorative LED lights (binary cct) 1W 1W Daily (1 hour)
Decorative 'mood' LED lights 2W 1W Daily (1 hour)
Shelf lights 8W 0W Daily (1 hour)
Porch lights 21W 1W Daily (2-7 hours)
Desk lamp 11W 0W Daily (1 hour)
       

If I go by the numbers above, I should save between 76 and 375 Watts per day as none of the above is on the grid any longer. This makes a saving somewhere between 0.3p and 6.9p per day depending on consumption and rate. These figures don't include savings made by using the portable equipment off the grid (i.e. charging batteries, iPod and mobile phones, the kids using their Leapster etc.) You can see that even a simple installation could take a while to pay for itself with these numbers - but my maths isn't great so don't take them as gospel. Instead, take a look at your own applications and your own numbers and if you want to play with the technology, go knock yourself out - it's kinda fun.

 

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