What heating appliances will still work with a restricted current?

Kernel_Sanders

penrhyn wrote: »

Your inverter will only work when its connected to the incoming mains, in the event of a mains failure it will shut down. Its designed this way to protect itself.

Doesn't sound very logical! I mean, your PV system is designed to fail at the time you most need it? (i.e. during a power cut).
Anyway, there are off-grid systems operating in remote areas. What do their inverters run on?

Cardew

Kernel_Sanders wrote: »

Doesn't sound very logical! I mean, your PV system is designed to fail at the time you most need it? (i.e. during a power cut).
Anyway, there are off-grid systems operating in remote areas. What do their inverters run on?

How do you think off-grid properties get their power at night? or any time when solar PV is not generating?

If you have a power cut - your system will shut down.

Martyn1981

Kernel_Sanders wrote: »

Doesn't sound very logical! I mean, your PV system is designed to fail at the time you most need it? (i.e. during a power cut).
Anyway, there are off-grid systems operating in remote areas. What do their inverters run on?

Evening Kernel, most domestic PV use GTI's (Grid Tie Inverters), they use the grid as a dump for excess power, hence why they shut down. Also it's a safety measure, if the DNO switches off power to do some maintenance, this feature prevents a PV array from frying the workmen.

Off grid users use similar equipment but it usually runs through batteries and is designed for off-grid use. In some cases, particularly with wind turbines, an off-grider may have a specific 'dump' electric water heating, electric bar fire etc that switches in to get rid off power peaks when the wind is really blowing hard, too hard/fast for the batteries to absorb.

Mart.

Dave_C_2

Kernel_Sanders wrote: »

Solar panels that produce electricity are photovoltaic, which means they work from light, not heat. In any case, I don't see where I am claiming that they will heat the whole house.

See thread title

You seem to be attaching a degree of importance to the fact that I am on Economy7. This is completely irrelevant, and I don't have storage heaters. I only mentioned it to explain why my daytime rate wa so high!

Now I'm confused! If you don't have storage radiators then why on earth are you on economy 7?

Dave

fwor

Interesting subject. To answer the original question, any type of heater that is purely passive, has no fan and has either no thermostat or a mechanical one should do the job.

In principle I can't see any reason why the inverter could not be made to run self-standing when it's been isolated from the grid, in a similar way to a battery-powered inverter.

But in practice you're probably going to be limited by what extra features (that the typical user will never need) are added to the control system by its makers, plus any safety constraints alluded to in Martyn1981's post (which is likely to rule out your "diode bypass").

The control system would need to have the ability for the system to generate its own 50Hz clock (not difficult), and for it to re-sync with the grid while running, neither of which would seem to be needed in a "typical" installation.

Cardew

Dave_C wrote: »

See thread title
Now I'm confused! If you don't have storage radiators then why on earth are you on economy 7?

Dave

Getting off subject a little, but things have changed regarding prices with Economy 7 lately.

In my area(Midlands) if you use 20% electricity on off-peak rates then the cheapest Economy 7 tariff(Scottish Power on line fixed May 2013) costs less than the cheapest single rate tariff(OVO).

In some Areas the 'break-even' point is lower than 20%.

Many people will exceed 20% without even trying.

Kernel_Sanders

penrhyn wrote: »

Your inverter will only work when its connected to the incoming mains, in the event of a mains failure it will shut down. Its designed this way to protect itself.

Just spoken to my installer, and you are correct.

spud17

fwor wrote: »

I know I'm going to demonstrate my lack of understanding of this subject, but...

Doesn't this defeat one of the main gains of the solar FIT? The fact that you get paid for whatever power you generate - even if you use it all yourself?

Do you know for sure that you're going to get paid the FIT even when you disconnect from the grid? I confess I don't know, but I suspect that you won't - in which case your scheme will simply mean you can only use the power, rather than use it and get paid for it.

I'm tending to agree with you. There is confusion about the various schemes.
e.g. Someone explained to me that the scheme was no good for them because they were out at work all day so would miss out on free power. :cool:

The original idea was, you sell all your wattage at 43p/unit against a purchase of approx 14p/unit.

So if your panels only generate 300w/winter day then you can have 900w back before you start paying.

Cardew

spud17 wrote: »

I'm tending to agree with you. There is confusion about the various schemes.
e.g. Someone explained to me that the scheme was no good for them because they were out at work all day so would miss out on free power. :cool:

The original idea was, you sell all your wattage at 43p/unit against a purchase of approx 14p/unit.

So if your panels only generate 300w/winter day then you can have 900w back before you start paying.

There shouldn't really be confusion. There are two schemes:

First where a house owner purchases a system and gets a subsidy(FIT) for every kWh they generate -was 43.3p/kWh soon/now will be 21p/kWh. In addition they can use as much as possible of the electricity they generate in the house.

Second the house owner allows a 'Rent a Roof' firm to install a system. The firm gets the subsidy and the house owner can use as much of the electricity as they are able.

The OP's aim, and that of everone is to use as much of the 'free' electricty as possible.

Given the unpredictable nature of solar electricity generation it isn't easy to increase the utilization of this free electricity. Indeed it is perfectly possible to find such attempts losing money.

Kernel_Sanders

Cardew wrote: »

The OP's aim, and that of everyone is to use as much of the 'free' electricity as possible.
Given the unpredictable nature of solar electricity generation it isn't easy to increase the utilization of this free electricity. Indeed it is perfectly possible to find such attempts losing money.

Another problem is the fridge-freezer; instead of using over a hundred watts during its cycle then nothing, it would be more helpful if it just used a smaller wattage continuously. Even then, my plug-in monitor shows that it uses several hundred watts just to start each cycle, so shutting off the mains is a no-go anyway in the Winter.
However, I've spoken to my supplier about this problem and he thinks there is a gadget on the market to solve this, although he has never fitted one. I'll keep you informed.