solar panels and night storage econ 7 Ask questions and find answers to many subjects relating to electrics and electrical work

[Mary Whittington]

Am having solar panels installed next week, can I get an electrician to take the electric storage heaters off Econ 7 and use the day solar generated power to heat the storage radiators. I'm out all day so want them to come on in afternoon and evening.

[ericmark]

Solar panels for heating are not normally electric. The way most work is to have a large storage tank which will store the heat and water filled radiators and pump.

While pump is stopped the energy is stored and when pump runs the energy is put into the house.

There are two main ways to store power. Hot water being one and batteries the other but you need so many batteries to store power they are not used for heating systems.

With photovoltaic cells the normal way to store energy is really a bit of a cheat. The power is sold to your supplier and bought back when required. The problem is the Labour government arranged the tariffs so you sell it for more money than you can buy it for so the supplier makes a loss. The new government has promised to look into this as clearly as more and more people take up the option the suppliers will need to increase their prices to all other users to offset their losses with solar panels.

There are some criteria that must be met which includes a minimum size of solar panel and a load of other conditions that must be met to get the export payment. These include a safe system so even though your panels are producing power if there is a power cut all the power is wasted to ensure no one working on the suppliers system can get electrocuted by your power back feeding.

So in real terms you are investing in solar panels for the use of all and will be paid for the power you produce but this is nothing to do with what you use. At least if your on the government scheme.

For the water solar panels there are two systems. One pressurised so needs testing every year and the other open vented. The pressurised one can store hotter water than open vented but it does not work well in areas with high lime content in their water.

The water and electric systems are completely different. Although you can fit immersion heaters in the water system to sink excess power if the sell back arrangement was stopped.

The electric system basic idea is to take money from the poor or people who's house faces wrong direction and pay it to rich who can afford to outlay to have it done and own their own house.

I own my own house and have the money but my house faces east/west not north/south so it can't be fitted. However one should ask yourself how long will the government allow this state of affairs to continue before they see it as an unfair distribution of wealth and stop the scheme?

[Mary Whittington]

EricMark I'm not trying to get a politcal argument going about the ethics of solar panels, just find out if I can run the radiators off the power produced in the day. I would have to save up for the modern electric storage radiators which can be run this way, just as I have to save up for everything else. There must be a way as it is an electric system and so amenable to command, I just don't have any idea of what to tell the electrician when I call to find out if its possible and get a quote for the work. Thanks anyway

[ericmark]

Sorry it seemed a political argument but not to tell you how things may change because of the political involvement in this subject would also be wrong.

The economy 7 and other systems to store energy when tariff is low to use latter using bricks was flawed in that one can't stop the head getting out during the day. The megaflow and other wet systems tried to redress this by using water to store the heat and it does work but requires much more space.

Electric heating has two draw backs. 1) the cost and 2) the total available power using solar panels will help with cost but will not help with total available power. So in a small property you could sell the power to supplier during the day and use it with a standard electric heater during the evening. You will not need storage heaters.

The tariff for feed in is:-
PV ≤4 kWp (new build) Domestic 36.1 pence 25 years
Now you must be aware that there is a minimum size. I think 1Kw peak power output which with solar panels is a lot. If you look at the "solarpower.co.uk/solar-power/solar-feed-in-tariff" web site it does explain how you are paid for the power you produce.

Being blunt solar panels are not economical viable without the grants and if there were no grants then the only use would be farming electric fences and boats, caravans etc where they reduce the need to run small petrol generators. To try and invent your own system although it may be sound in theory because to get payment you need to follow the government requirements is not really worth contemplating.

The water heating solar panels work well go to any Mediterranean country and you see them in use all the time. However for maintenance one needs a flat roof not the pitched roof used in this country. Already we have Sky users who have to abandon the existing dishes due to heath and safety rules which prevent them going on the roof without scaffold. The same problems are likely with solar panels. And unless you have a flat roof then likely to cost a fortune every time there is slightest fault.

There are some very good salesmen out there. But very few electricians have solar panels. Ask yourself why?

[Jilly P]

Am having solar panels installed next week, can I get an electrician to take the electric storage heaters off Econ 7 and use the day solar generated power to heat the storage radiators. I'm out all day so want them to come on in afternoon and evening.

Hi Mary, we too are awaiting the arrival of a roof-ful of solar panels, and I am right now investigating as to whether we can easily run storage radiators from the poer produced. The chap who came to sell us the system (Beco) was rather surprised when we suggested it as an option, but I think we shall be looking to get hold of a couple of the older type night storage heaters that in fact we had in our first house some 30+ years ago. The bulky kind that have rows of hevy bricks inside them. My husband is a handy type of chap, so he will no doubt be able to 'make it happen'. I do appreciate that when the heat is most needed will be when the solar panels will be producing less electricity, but we think that if we install one storage radiator under the stairs in the heart of our barn conversion, it can only add to the general warmth of the building. Plus the electricity used will not cost. We shall be looking to our local freecycle website, because people are now only too happy to offload these old dinosaurs.
I would be most interested to learn if you have any success at your end, and happy to get back in touch with you as our installation, and then hopefully, our fit (of radiators) takes place.
When he was in his teens, my husband lived up the canal in a lock keepers cottage, and their only means of power was from a windmill, which gave them enough power - stored in old bus batteries to power lights and a 12 volt television. So being resourceful comes naturally to him. Regards Jill Pendleton.

[jsheerin]

Hi Mary, we too are awaiting the arrival of a roof-ful of solar panels, and I am right now investigating as to whether we can easily run storage radiators from the poer produced.

Hi Jill
Did you ever find an answer to your question? We had someone come round the other day trying to sell us "free" photovoltaic panels. My wife is disabled so spends most daylight hours at home (using washing machine dishwasher etc. as well as cooking, lighting etc. I then thought about the potential for using storage, connected to the standard household supply so that they charged up during the day, making maximum possible use of electricity generated by the panels. I guess the answer is probably in the terms of the agreement with the company providing the panels but I'd still be interested as to what, if any, answer you found. Best wishes James

[woody01]

Hi

I'm new to this forum, so please bear with me if I get it wrong. I hope to widen the discussion a little.

We are having a 1.84kw photovoltaic system fitted on our flat roof in a few days time. A friend down the road had a similar system installed in April this year and is very pleased with the result. We are using the same company.

According to the blurb, not only do we get the feed-in tariff, but any electricity we generate that we can use ourselves is free. This is the challenging bit. Selling it on to the grid at 3p per unit is not that attractive.

In order to use all the available electricity ourselves, we need a gadget of some sort that detects the available energy coming down the wire, and feeds exactly that amount into something useful. We had a think about this and came up with the idea of using an old fashioned storage heater to charge up during the day when we're out, and release some heat in the evening when we're in. The tricky part though is matching supply to load. So far all I can think of is a series of heating elements which would be progressively be switched on as the day brightened up and vice versa. The hard part is working out the control mechanism, and ideally it would be progressive rather than stepped.

So that's the challenge. Any ideas would be welcomed. I quizzed the surveyor who agreed it would be a good idea, but couldn't come up with an answer..

Any electricians out there?

Regards, John

[BLAKEY1963]

[quote="woody01"]Hi

I'm new to this forum, so please bear with me if I get it wrong. I hope to widen the discussion a little.

We are having a 1.84kw photovoltaic system fitted on our flat roof in a few days time. A friend down the road had a similar system installed in April this year and is very pleased with the result. We are using the same company.

According to the blurb, not only do we get the feed-in tariff, but any electricity we generate that we can use ourselves is free. This is the challenging bit. Selling it on to the grid at 3p per unit is not that attractive.

In order to use all the available electricity ourselves, we need a gadget of some sort that detects the available energy coming down the wire, and feeds exactly that amount into something useful. We had a think about this and came up with the idea of using an old fashioned storage heater to charge up during the day when we're out, and release some heat in the evening when we're in. The tricky part though is matching supply to load. So far all I can think of is a series of heating elements which would be progressively be switched on as the day brightened up and vice versa. The hard part is working out the control mechanism, and ideally it would be progressive rather than stepped.

So that's the challenge. Any ideas would be welcomed. I quizzed the surveyor who agreed it would be a good idea, but couldn't come up with an answer..

Any electricians out there?

Regards, John[/quote]



JOHN
Get in touch with the manufactuer of your solar panels and see if they have a techical help line department. Explain your query and they might be able to help with a suitable solution.
you could also try the net for suitable products

BLAKEY1963

[ericmark]

The power from the solar panels is fed into a grid tie inverter which varies the input voltage to match the amps as in the low light conditions the voltage input is low but in high light conditions the voltage is high to get maximum watts this means to tap into DC power is near impossible.

The whole idea of feed in tariff is not to sell the power to grid but to use the grid as a battery. So when the cells are producing you pump into grid and when they are not you draw out of the grid. Having east and west facing roof I can't use solar panels but looked into it for using on a boat.

What you need to find out is over what period is the charge/payment made. If it was for example over the year then what you produce in the summer will balance out what you use in the winter. If by the day then what produced in day will balance out what is used in the night. It seems the tariffs have changed at one time people were paid more for what they put into grid than charged for what they took out. But without detailed information on both charges/payment and period it is worked over impossible to work out.

[witney]

Hi
I too am about to have pv panels fitted and have been thinking how to use the free daytime electricity.

I did think of storage radiators but have remembered what a pain they were when changing any settings. If they have not got better controls then they might just eat daytime electricity regardless of whether the panels are collecting 'free' electricity. They must be able to be plugged into normal sockets - they only used Economy 7 because it's cheaper. Nothing magical about the electricity.

I seem to remember you can get oil filled radiators which would hold the heat for some time and might be better tempered about a supply that might be off sometimes then on again.

As john mentioned a key ingredient is something that only uses electricity when it is being prouced by the panels. With all the advances in technology I am sure it is possible, but have not heard of a solution yet. WIll keep on looking as I hope everyone else will. This is a real need to store up the heat for the evenings without taking any power from the grid.
Sandy

[ericmark]

I think you have missed the point. The grid-tie inverter is designed to use the national grid as a battery. So you pay for the power over a set time not minute by minute. So if the set time is one week they take what you put in away from what you took out and you pay or receive payment for average difference over whatever is the time period set.

So if you end up over a set time using less than you produce then your paid and yes the amount now (It was not at start of this thread) you are paid is very low. However to use storage heaters of any type the problem is to stop the output when not required and with the bricks at 1000 degrees you can't stop some of the heat getting out. The more expensive type use water and at 85 degrees you can insulate very well to stop it escaping. However it seems rather inefficiency to use photovoltaic cells to heat water. If you want to heat water you can do that direct.

Look up Willis Renewables - Solasyphon - How it works and it will explain how to use the sun to work a heating system. It's complete nonsense to use the system your talking about to heat a house.

[sparx]

Hi all,
as has been said on here I believe the whole operation of these systems is being misunderstood.
Lets take an example of a system which on a sunny day produces 2kW of energy.
the system can't be just connected to a piece of equipment such as a heater, it would be pointless anyway as the only time heat would be available would be days when you don't need it!
Anyway all the systems being commercially fitted to houses must by law and to comply with wiring regs be 'grid-tied' which means they must connect to the house system. This is for safety reasons and so if the power fails your system MUST cut off- so no good in power cuts as some people think!
All our homes always use some power, even if only for fridge, freezer, TV standby etc. lets say average 500w the 1500w surplace is fed back into the grid and you are credited that much via the 2 way electricity metering at a premium rate (recently reduced).
if you use 3 kW (3000w) then you get the first 2kW free and pay at normal rate for the extra 1kW used.
As an aside for anyone thinking of solar power either water or PV don't fall for the big sales lie of
"you don't need sunshine, only daylight" C*bblers!!!
We have just successfully sued for all our money back on our solar HW system installed on that untruth!
(£6000+). Five winters averaging 5 months each having to use immersion heater to get a hot shower.
S-E England, south facing, 30 miles from France so not bad location.

[ericmark]

Thank you for a real reply. I know my daughter (with a flat in turkey) does use solar power. But one has to shower in the evening not the morning.

With a son who until the last year lived on a narrow boat the whole idea of solar power was something which was very much debated. To produce enough to maintain the batteries was a good idea. However to produce enough to live on was another story.

The idea of grid-tie is to remove the need for a battery. My son did not have that option. But one of the big problems with the photo-voltaic cells is the running voltage. As the day progresses the voltage at which max output is extracted also varies. So a special device able to best match the voltage is required. There are a host of units made all which claim they do the job better than the rest at matching the output so gaining the most from the power available.

But as to which really do the best job is just guess work. Location and direction that the panels face will make a huge difference. But putting it simple the companies lie. So to work out if in real terms it will pay is something of a lottery. I am sure some do work. But most are a waist of money.

[Ricardohos]

Replies haven't actually been anything much to do with the specific question and are a little vague - in fact one of them 'you won't need storage heaters during the day' totally misses the point.

So I'm in the same position here - wondering about getting storage heaters that I can run during the day to replace central heating. 2 x 1.7kw heaters for instance running from 10am to 2pm would charge nicely for the evening and would be free electricity. Do you realise Ericmark that it's not just the FIT you get, but you also get free electricity during the day?

I know a lot of solar pv people are now getting into lower wattage immersion heaters to do the hot water - on a timer from say 12 noon to 2 pm = free hot water.

[Ricardohos]

I think what this discussion has raised is that there's people who really don't understand the system. It also raises the prospect that for the next 25 years people who managed to get in on the best FIT rate are going to find ever more ingenious ways to use their free electricity. Remember, whatever you produce yourself in the day is free to use AND you get paid for it on top of that at 43p / KW. If you ALSO don't use it then you get 3p / KW as buy back. It is clearly much better value to use it!!! I've installed a 4KW system and even when not operating to 100%, which it won't, it will be advantageous to use as much electricity during the day as I can.

Here is one company that understands what this thread was all about at the beginning, and which looks to be finding the solution: Google "sukaelectroheating.co.uk"