Saving energy

I switch most things off rather than leave them on standby - they do add up. Also I feel safer at night if there are not too many things humming!

Another one here who turn off many electrical appliances at the mains when not in use vis. Cooker, dishwasher, washing machine, TV, video, etc.

Mainly for safety reasons.

We lived off grid for 20 years so we are well aware of energy usage. Thank goodness for LED bulbs. In the conservatory alone there are 20 lights.

I am indeed watching this space Beattie9 with great interest. I know I have become rather lax as the winter rolled on.

petra off grid for 20 years! Interesting too.

We have 16 solar panels which on fine sunny days do generate a fair bit of power. I try to use the washing machine, dishwasher and iron when the sun is shining. Our house is heated by a ground source heat pump so we try to run the pump when the sun is shining.

Beattie, thanks for this. I've been aware of my blissful ignorance of the energy consumption of household appliances, and I'm not even sure how much a unit of electricity currently (pun intended!) costs.

I need to pay attention to this. Can I ask what you use to measure consumption please?

Parsleywin
Tariffs vary, but if you work on the basis of 1 kWh (1 Unit) costs 15p (incl VAT @ 5%), you shouldn't be too far out.

As I don't possess a wattmeter I used two industry-standard digital multi-meters (DMMs), one to measure the voltage and the second to measure the current drawn by the appliance using an 'intercept' box.

This box is fitted with two sets of shrouded sockets to receive the probes from the DMMs. Two flexible cords exit the box, one going to a 13A plug, the other to a 13A trailing socket. The appliance-under-test is plugged into the trailing socket and the 13A plug into the wall socket.

The figure for the power is arrived at by calculation from:
Power (in Watts) = Voltage x Current (in Amperes)

Strictly speaking, the result of the calculation is only accurate for purely resistive loads such as kettles, toasters, irons, tungsten lamps, etc.

When using the above formula for appliances that have wound components (e.g. motors) and capacitors, a slightly inaccurate result occurs but usually this is small enough to be ignored in most cases.

I would not advocate anyone attempting what I have described unless you are electrically competent. A safer but less convenient way of measuring the power of an appliance is to switch on the appliance, then watch the electricity meter. If you still have the old style meter with dials, the red dial is calibrated in tenths of a kilowatt-hour. If your meter is the later digital type, count the number of flashes its light makes over a measured period of time, say five minutes. The meter will have a figure of how many flashes correspond to one unit. (If you have a Smart Meter, do as I did and have it removed!) As I say, hardly a convenient method, especially if you want check several appliances but it's slightly more interesting than watching paint dry!

For appliances in the second category (above) the same errors will be present since energy meters cannot measure consumption of installations with low or poor Power Factor (PF)

Apologies for slipping into 'technical mode'; old habits die hard!

Reading my last posting, I have noticed an ambiguity in the penultimate paragraph; it should read:

...energy meters cannot measure consumption of 'apparent' power of installations with low or poor Power Factor (PF)

Solar panels (aka photo-voltaic or PV, to differentiate from solar heating) are a serious consideration for anyone aspiring to be 'green' in their energy thinking or those wishing to reduce dependency on the public supply network.

As many people will know, a few years ago the government were concerned that national electricity consumption was fast approaching net generating capacity and this, coupled with the planned decommissioning of coal-fired power stations prompted a strategy of energy conservation and self-reliance to be encouraged amongst the population.

Solar panels were seen as one solution that many ordinary house owners and businesses could adopt to stave off potential shortfalls in generating capacity. Consequently, the government offered generous 'feed-in tariffs' to encourage those with predominantly south-facing roofs to consider a PV installation.

And a great many did! Such was the level of the feed-in, that companies offering PV installations began popping-up all over the country!

The big attraction of the scheme to the home owner was discounted electricity, since PV-generated energy is fed back into the Grid, effectively turning every installation into a mini-power station.

Unless the home owner or business could afford the typically thousands of pounds to own their own, the installation was owned, either by the installer or A N Other, who effectively rented the area of the roof (by offering discounted electricity) for a period of perhaps 25 years.

As I understand it, the current situation is one where the feed-in tariff has been drastically reduced, with the result that several installers have either gone out of business or switched to other sources of income.

On the plus side, PV solar panel technology has improved dramatically over the last couple of decades. An oft-quoted figure for the theoretical amount of energy available from sunlight is 1kW per square metre. Unfortunately, this figure is reduced if the sun is not directly overhead (angle of incidence < 90 degrees).

Tilting of the panel can compensate but this is not usually an option when mounted on a roof; the angle of incidence then tends to match the pitch of the roof.

Then there is the efficiency of the PV panel itself at typically 15% resulting in a theoretical energy yield of 0.15kWh per square metre. So with a PV array of say, 10 sq metres and a mean of 5 hours of useful sunlight per day, perhaps 7.5kWh per day may be possible.

This figure will be reduced on dull and rainy days and off course, will be near zero at night. Which brings me to my next point: many PV installations are 'online', generating only when conditions are ideal and with no capacity for storage of generated energy.

An example of this is a local transport museum that had a 15kWh array installed some years ago that didn't include storage; all of the energy went back to the Grid with only a negligible amount used in the building during the day.

Unfortunately, there had been some kind of mix-up in the setting-up of the account that resulted in the museum not receiving a penny in generating revenue over a period of several years! I believe that has now been sorted but the fact remains that as the museum is either open in the evenings or people are working on the vehicles at that time, lights are required that are not powered from the very expensive array!

The cost of storage batteries and charging equipment is naturally another factor to be considered as is the fact that there is another efficiency loss in the conversion of energy from PV-to-battery-to-inverter (for mains voltage equipment) or low-voltage lighting.

But it can only get better!

Ah Beattie, I wish I could understand all that you are saying you certainly sound very knowledgeable. I can wire a plug, but that's about all. There are two of us in the house and are reasonably careful about power use, usually, but don't let it rule our lives. We do have 16 solar panels fitted, and had them installed in early 2012. They will have generated enough income to have paid for them selves, very shortly this year. DH also says that with the FIT income, it covers enough to pay for our Gas, Electricity and Water bills. So they have been a success, with, fingers crossed, no problems.

Auntieflo

It's horse for courses, I guess!

My background is engineering! Apologies if some of my posts are overly-technical; I try to give readers the full picture!

Glad to hear that the great news about your installation. Solar panels are an undoubted success and the energy is clean and free!

May the sun keep shining on you!

I have ordinary solar panels, not PV and they do save me money for hot water on a light day, The sun does not have to be shining but zilch happens when the sky is grey. It is not a council house but the council offered this at a discounted price in 2009.

The only thing I do not switch off at the mains is my TV and Humax because of late recording and updating.

Beattie I am another who is lost but that is not difficult.

Charleygirl

Although familiar with the principle, I do not have first-hand experience with solar heating panels.

I am presuming that your installation closed-circuit in design? (Closed circuit implies a system of small-bore pipework, usually black in colour, that snakes across the roof whereas an open-circuit design trickles water down the roof, to be collected at the bottom)

Closed-circuit is the better system since no water is lost to evaporation and usually contains additives to reduce the risk of corrosion and freezing.

Regarding leaving TV on standby: although there is a cost implication, perhaps 1kWh or more per day, the convenience aspect probably out weighs the cost.

Furthermore, TVs are much safer than they used to be. In the past, some house fires were attributed to equipment being left in standby but these tended to involve the heavy, boxy CRT televisions.

TV sets of that age would invariably be analogue receivers that incorporated circuits called AGCs to compensate for varying strengths of received signals from an aerial/antenna.

In the days before 24-hour broadcasts, if a set was left on with no signal being received, the AGC circuit would ramp up looking for what the TV thought was a weak signal! This generated additional heat in the receiver which, if left unattended for perhaps hours, could give rise to a fire risk.

Please don't be lost! If I can answer your questions, I'd be more than happy to oblige.

I definitely do not have black pipes snaking down my roof. Most of the apparatus is in the loft and the remainder in the airing cupboard where I could read the meter if I was not partially sighted!

What I do not like about this system is that the first I was aware of a problem, the ceiling in a bedroom was bending and then cracked letting drips of water through. Fortunately there is a finite amount of water so the house was not flooded.

So there is nothing visible from outside? That's has to be a plus!

Two lovely pieces of supposedly self cleaning glass! It looks smart or it would not have been fitted, cheap or not!