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So now I have a solar PV system how do I make the most of it???
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# 1
teachergirl
Old 02-01-2011, 8:25 PM
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Default So now I have a solar PV system how do I make the most of it???

Dear all. I know there are several threads about solar PV but many of them are debating whether or not they are a good idea and if the free ones are worth having. All of which is valid debate. Stuck in the middle of some of these threads I have found the odd tip about how to make the most of the generated electricity but they can be difficult to pick out.
So I wondered if we could have a new thread where people share their tips for making the most of the electricity that they generate.
Our system was put up just before Christmas in a snow storm. We haven't exactly generated much electricity but as we are all at home for the holidays we have changed our usage habits and used our appliances during the day. When we go back to work we will have to use the timing devices to get our appliances to come on during daylight. Now at the moment that is the only thing I can think of doing. However I have picked up so many handy tips from these forums I wondered if we could share our ideas as there are bound to be some clever people out there who have lots of MSE ideas
Thanking you all in advance

Official MoneySavingExpert insert: There are some great hints and tips on how to get the most from solar panels. Thanks to all who contributed!
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Last edited by MSE Debs; 21-02-2012 at 8:19 PM.
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# 2
Jon Tiffany
Old 02-01-2011, 9:04 PM
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Congrats on joining the solar pv club! Firstly some good news - the days are getting longer now and you will see the output from the panels increase considerably over the next couple of months.

A good place to start is dishwashers and washing machines as you have control and flexibility over when they are run. We try to save up washing as much as possible for the sunnier days, this works out well as sunny days are great for then putting the washing out to dry.

We tend to run the washing machine from around 10am and then the dishwasher from about 1pm. We have an electric oven and grill so try to leave a space at lunchtime.

Regarding appliances such as washing machines the two main points are:

1 - dont run them all at the same time, stagger them, i.e run them one after the other

2 - Dont be tempted to run part loads.

I have a few more tips that I will save for another post.
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# 3
teachergirl
Old 02-01-2011, 9:34 PM
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Brilliant.thank you. This is just the sort of tips i was hoping for
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# 4
Hetty17
Old 03-01-2011, 1:37 AM
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also think about kit that you plug in to charge up occasionally: mobile phones, electric toothbrushes, drills, rechargeable batteries, and so on.
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# 5
Cardew
Old 03-01-2011, 1:55 AM
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The point made above about not being tempted to run part loads is important.

Modern washing machines for example don't use much electricity(0.4kWh or 0.6kWh) is typical. So the savings on electricity will often only be a couple of pence - or nothing on a dull winter's day - and there will be no saving on the cost of water and detergent.

The same principle applies to dishwashers. When we had economy 7 it was a temptation to run them at night when there was still space for, say, breakfast dishes.
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# 6
kittie
Old 03-01-2011, 8:41 AM
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See what is actually being produced at a moment in time and then decide what you are going to run and always keeping an eye on the weather. Obviously your fridge and freezer will be running anyway so that is a basis. Then I re charge torches, toothbrushes, radios and laptops when there is more than minimum being produced. Going up through the breadmaker and so on. The washing machine is a bit different for me as we have rainwater harvesting to take into account and I use eco balls or soapnuts when I can, plus cold washes and quick washes when things just need a rinse. I try to stagger electricity usage during the lightest hours

I have ordered an owl monitor so I get a better idea of the energy used by the oven v the remoska and the fridge etc and I will gradually make a chart for us to refer to

I input readings into imeasure and that tells me that our electricity cost from the middle of june to now is £167 (and most food is home made ie jam, oven, ice cream etc)

just to add that I bought a really good de-hydrator which I will use during the summer months to help preserve onions, tomatoes etc from my new allotment. This will make better use of the highest production from the pv system

Last edited by kittie; 03-01-2011 at 8:47 AM.
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# 7
teachergirl
Old 03-01-2011, 9:52 AM
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Thank you everyone.
Cardew I must admit I can see the temptation to put on a half load but I will think more carefully about it now. As I will be back at work I think sometimes my use of the washing machine wil have to coincide with when I have time to iron afterwards! Charging stuff is a great thought too. it would be really good if there were lights and heaters that you could charge up in the day and then get them to release the energy at night. I suppose though that the time you would be able to do this most would be in the summer when you would not actually need them
kittie I also have an owl monitor and must start looking at the electricity consumtion...the bread maker is also a fabulous idea . BTW what is a de-hydrator? We also have an allotment and often have too much to use.
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# 8
rhiwfield
Old 03-01-2011, 1:54 PM
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One or two thoughts.

The electricity is produced in a bell curve, the size of the bell getting bigger until it peaks mid-summerish. ATM its quite small (low angle of sun and low length of day). The amount of leccy being produced at the peak of the day may be 3x as much in strong, summer sunshine as it is now, and the system may well produce 8x as much then. So using your leccy productively in the summer will be harder than it is now

When days are really dull in winter generation will probably be accounted for largely by base load (central heating pump, fridge, freezer etc, sensors, displays)

Many appliances dont use leccy evenly (dishwasher, washing machine, breadmaker, electric oven, microwave on low settings) or use high kW: eg kettle say 3kW, showers 8-10 kW.

Constant (ish) appliances seem to be: lighting, tv, computers, monitors, set top box, electric hobs, toaster, tumble dryer, hoover, microwave on full (which uses about 1.5x rated output) Not sure about slow cookers, iron.

As you can see it'll be a juggling act to keep varying use in line with varying production. I find it helps to keep a monitor in the kitchen/utility (where most usage is started) and (keeping in mind Cardews valid point about running appliances efficiently) try to manually balance usage against (over-baseload) generation. The more time you have to play the better you'll get but some tips:
  • Switch usage times about e.g. Cook evening meal during day
  • Save winter washing/drying/ironing for good generation days
  • Hoover when the sun shines
  • Get to know quirks of your machines e.g. my dishwasher has two periods of heating on eco setting, so stagger this with heating period of washing machine.
  • Avoid combining heating times unless you have surplus generation
  • At certain times you may find in winter that you still cant use generation. Thats when a fan heater/radiator can be switched on at say 750W or 1.25kW setting to add to the house's heat sink.
  • This one I havent yet tried but using a heat pump is likely to ensure you use all generation in winter, early spring/late autumn
  • FWIW I was given an old dehydrator and that might be a good part use of surplus summer leccy, when we'll be really struggling to use what we generate, especially as we grow our own fruit.

Last edited by rhiwfield; 03-01-2011 at 1:56 PM.
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# 9
kittie
Old 03-01-2011, 2:43 PM
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teachergirl, I bought an excalibur

http://forums.moneysavingexpert.com/...ht=dehydrating
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# 10
penrhyn
Old 03-01-2011, 4:32 PM
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Why does it matter when or indeed if you use any of the energy produced by a solar PV array, as you are well paid by the FIT for all the power you generate?
Winter is coming
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# 11
Jon Tiffany
Old 03-01-2011, 5:58 PM
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Quote:
Originally Posted by penrhyn View Post
Why does it matter when or indeed if you use any of the energy produced by a solar PV array, as you are well paid by the FIT for all the power you generate?
For some of us this is as much about doing our bit for the environment and UK energy security as it is about the money.

The more we can use at home the less we import from the grid that we have to pay for, so maximising the money saving aspect.

Environmentally, there are many benefits. It makes people much more energy aware, it helps move peak demand to be more evenly spread, there are no 10% transmission losses. In terms of the CO2 payback time estimates range from 2 years to 4 years at the most pessamistic.

We have gone from a net exporter of energy to a net importer. We even now get gas from as far as Qatar.

Have you seen the price of oil lately?
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# 12
Jon Tiffany
Old 03-01-2011, 6:04 PM
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Quote:
Originally Posted by rhiwfield View Post
One or two thoughts.

The electricity is produced in a bell curve, the size of the bell getting bigger until it peaks mid-summerish. ATM its quite small (low angle of sun and low length of day). The amount of leccy being produced at the peak of the day may be 3x as much in strong, summer sunshine as it is now, and the system may well produce 8x as much then. So using your leccy productively in the summer will be harder than it is now

When days are really dull in winter generation will probably be accounted for largely by base load (central heating pump, fridge, freezer etc, sensors, displays)

Many appliances dont use leccy evenly (dishwasher, washing machine, breadmaker, electric oven, microwave on low settings) or use high kW: eg kettle say 3kW, showers 8-10 kW.

Constant (ish) appliances seem to be: lighting, tv, computers, monitors, set top box, electric hobs, toaster, tumble dryer, hoover, microwave on full (which uses about 1.5x rated output) Not sure about slow cookers, iron.

As you can see it'll be a juggling act to keep varying use in line with varying production. I find it helps to keep a monitor in the kitchen/utility (where most usage is started) and (keeping in mind Cardews valid point about running appliances efficiently) try to manually balance usage against (over-baseload) generation. The more time you have to play the better you'll get but some tips:
  • Switch usage times about e.g. Cook evening meal during day
  • Save winter washing/drying/ironing for good generation days
  • Hoover when the sun shines
  • Get to know quirks of your machines e.g. my dishwasher has two periods of heating on eco setting, so stagger this with heating period of washing machine.
  • Avoid combining heating times unless you have surplus generation
  • At certain times you may find in winter that you still cant use generation. Thats when a fan heater/radiator can be switched on at say 750W or 1.25kW setting to add to the house's heat sink.
  • This one I havent yet tried but using a heat pump is likely to ensure you use all generation in winter, early spring/late autumn
  • FWIW I was given an old dehydrator and that might be a good part use of surplus summer leccy, when we'll be really struggling to use what we generate, especially as we grow our own fruit.
Excellent post. Just to add, its really good to have an energy monitor to get a feel for what sort of leccy appliances are using and when. I had a monitor for some time before I had the panels so I had a really good feel for what uses the most electric.

Note that if you use an energy monitor once you have panels fitted it will only be measuring your net import or export - this will not be the same as what you are using in the house.

E.g An energy monitor would only read 100w if you were consuming 800w in the house and your panels are producing 700w (import of 100w). It would also read 100w if you panels are producing 900w and you are using 800w (export of 100w)
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# 13
kittie
Old 03-01-2011, 6:14 PM
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Ah yes, thanks for that Jon. I see some additional maths coming up as I want a fairly accurate range of readings for my appliance usage
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# 14
penrhyn
Old 03-01-2011, 6:38 PM
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Quote:
Originally Posted by Jon Tiffany View Post
For some of us this is as much about doing our bit for the environment and UK energy security as it is about the money.

The more we can use at home the less we import from the grid that we have to pay for, so maximising the money saving aspect.

Environmentally, there are many benefits. It makes people much more energy aware, it helps move peak demand to be more evenly spread, there are no 10% transmission losses. In terms of the CO2 payback time estimates range from 2 years to 4 years at the most pessamistic.

We have gone from a net exporter of energy to a net importer. We even now get gas from as far as Qatar.

Have you seen the price of oil lately?
You are still generating the 'off grid energy' whether you are using its yourself or someone else on the grid is making use of the couple of watts you are exporting.

The point you make about gas is a good one, however solar energy will make zero contribution to the need to heat our homes during the winter months.
Winter is coming
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# 15
Jon Tiffany
Old 03-01-2011, 6:59 PM
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Quote:
Originally Posted by penrhyn View Post
You are still generating the 'off grid energy' whether you are using its yourself or someone else on the grid is making use of the couple of watts you are exporting.

The point you make about gas is a good one, however solar energy will make zero contribution to the need to heat our homes during the winter months.
Yes, good point. Any excess that is exported will be used by the surrounding properties.

Solar will make some, albeit small contribution in the winter months. I've seen some surprisingly high output on days in December, but of course the days are short and gloomy so the overall output for december is only a fraction of what you get in summer.
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# 16
Jon Tiffany
Old 03-01-2011, 7:01 PM
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Quote:
Originally Posted by kittie View Post
Ah yes, thanks for that Jon. I see some additional maths coming up as I want a fairly accurate range of readings for my appliance usage
You might want to look at a plug in meter if you want accurate readings for each appliance. They had some in ALDI's the other week on the specials, under a tenner from memory.

The problem with the energy monitors is that they can not tell the difference between import and export which makes things a little tricky.
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# 17
rhiwfield
Old 03-01-2011, 7:34 PM
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Quote:
Originally Posted by penrhyn View Post
Why does it matter when or indeed if you use any of the energy produced by a solar PV array, as you are well paid by the FIT for all the power you generate?
I agree with Jon Tiffany's earlier answer but would not deny, from a financial viewpoint, it makes sense to use your own (free) electricity rather than paying to import from the grid at 10p per kWh. But anything not used, and in a year in my case that will be probably 1500 kWh, will be used by my neighbours with virtually nil transmission loss.

To minimise fossil fuel use for heating I'm considering installing a bivalent heat pump which will use surplus self-generated leccy in part, even in winter months, though I grant it will be very little at times. Any such use will multiply benefit by c2.5x, so I wouldnt be surprised if the pv was responsible for generating maybe 1500 kWh of heat via the heat pump over winter, spring and autumn. A minor part of the heat load, but worthwhile.
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# 18
rhiwfield
Old 03-01-2011, 7:38 PM
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Quote:
Originally Posted by Jon Tiffany View Post

Note that if you use an energy monitor once you have panels fitted it will only be measuring your net import or export - this will not be the same as what you are using in the house.
Spot on, unless the panels aren't generating.

If in doubt I quickly switch on/off an oven ring at low setting to check which way the current is flowing.

The other issue with monitors is that they are susceptible to "noise" and give false readings at low levels.

Last edited by rhiwfield; 03-01-2011 at 7:40 PM.
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# 19
Jon Tiffany
Old 03-01-2011, 7:51 PM
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Quote:
Originally Posted by rhiwfield View Post
To minimise fossil fuel use for heating I'm considering installing a bivalent heat pump which will use surplus self-generated leccy in part, even in winter months, though I grant it will be very little at times. Any such use will multiply benefit by c2.5x, so I wouldnt be surprised if the pv was responsible for generating maybe 1500 kWh of heat via the heat pump over winter, spring and autumn. A minor part of the heat load, but worthwhile.
I've been looking at heat pumps as well. I think they would work exceptionally well in autumn and spring when outside temps are mild, pv output is good and only low level background heating is needed. However, for the winter months it would be mostly leccy from the grid that would power it.

Currently I dont think it would make financial sense to invest in a heat pump unless you need to replace a heating system anyway or if you dont have access to mains gas.

My feeling is that the price gap between electric and gas will shrink in the coming years as we depend ever more on imports.
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# 20
Zenoka
Old 03-01-2011, 9:33 PM
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Does anyone know if there is a device that can sense when you are exporting and send that electricity to a hot water heater? We would really like to use the surplus to help towards heating our water, DH is good at diy and is already talking about fitting a 500w imersion, but we want a system that will automatically control it for us.

Does such a thing exist? I've searched but not been able to find anything.
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