Rent-a-roof - questions on contracts people have signed.

energysavingexp

rogerblack wrote: »

Ah - I see where this comes from now, I omitted important stuff for simplicity.

Specifically, I'd be using a device which is basically a dimmer, with a clip-on sensor to the meter.
If there is any inflow of power, it turns down the 'dimmer' essentially instantly.

So it never uses any extra power from the mains.

you say using a clip-on sensor how will you get it to distinguish which way the current is flowing

ie how will it now wether is importing or exporting

if you fit it on the tails from your inverter say its delivering 2kw

you might be importing another 2kw so your house old load is 4kw

so if it is fitted on to these tails your dimmer will think its exporting and turn on heater pulling even more from the grid

now if you fit the clip-sensor on the incoming tails up to the fuse box the sensor wont know which direction the current is going

so say you are exporting 2kw your dimmer will turn on the heater, fine but say its clowdy and you are importing say 2kw your sensor will see a flow of 2kw and turn on the heater and now you will be importing even more.
the only way it will work is if it can sense different directions of current flow

zeupater

energysavingexp wrote: »

you say using a clip-on sensor how will you get it to distinguish which way the current is flowing

ie how will it now wether is importing or exporting

if you fit it on the tails from your inverter say its delivering 2kw

you might be importing another 2kw so your house old load is 4kw

so if it is fitted on to these tails your dimmer will think its exporting and turn on heater pulling even more from the grid

now if you fit the clip-sensor on the incoming tails up to the fuse box the sensor wont know which direction the current is going

so say you are exporting 2kw your dimmer will turn on the heater, fine but say its clowdy and you are importing say 2kw your sensor will see a flow of 2kw and turn on the heater and now you will be importing even more.
the only way it will work is if it can sense different directions of current flow

Hi

Unless your system is installed with a separate consumer unit and a henley block then you would have ability to read net usage, consumption or generation depending on where the clamp sensor is placed.

I'm interested in where rogerblack is going to source the proposed device, I've seen home made units and I've seen units costing well over £1k, but nothing off the shelf at a reasonable cost.

The only sensible solution would be to simultaneously measure generation and consumption, compare the two and use logic to control a relay switched load when generation outstrips consumption by a set margin .... this could be achieved with a plc and a couple of clamp sensors, a little programming logic, an output and a relay ...

HTH
Z

energysavingexp

zeupater wrote: »

Hi

Unless your system is installed with a separate consumer unit and a henley block then you would have ability to read net usage, consumption or generation depending on where the clamp sensor is placed.

I'm interested in where rogerblack is going to source the proposed device, I've seen home made units and I've seen units costing well over £1k, but nothing off the shelf at a reasonable cost.

The only sensible solution would be to simultaneously measure generation and consumption, compare the two and use logic to control a relay switched load when generation outstrips consumption by a set margin .... this could be achieved with a plc and a couple of clamp sensors, a little programming logic, an output and a relay ...

HTH
Z

if you fit it where you can measure net usage, consumption then you are not measuring export if you fit it exit of inverter you will measure production before consumption/export
if its fitted on the main tails it will measure either inport or export but how can it differentiate inport or export

i agree with you the ideal solution would be to simultaneously measure generation and consumption, compare the two

i have made a system for my solar panels that turns things on when exporting and off when importing
its been fitted for about 3 weeks now it a very simple device total cost less than £10
it now turns on my towel rail in the bathroom

i would love to see a circuit diagram of his proposed system that he is planning on using

zeupater

energysavingexp wrote: »

if you fit it where you can measure net usage, consumption then you are not measuring export if you fit it exit of inverter you will measure production before consumption/export
if its fitted on the main tails it will measure either inport or export but how can it differentiate inport or export

i agree with you the ideal solution would be to simultaneously measure generation and consumption, compare the two

i have made a system for my solar panels that turns things on when exporting and off when importing
its been fitted for about 3 weeks now it a very simple device total cost less than £10
it now turns on my towel rail in the bathroom

i would love to see a circuit diagram of his proposed system that he is planning on using

Hi

Agree, consumption is on tail between henley block and main consumer unit, generation is on tail between henley block and inverter consumer unit (inverter must be protected) and net reading is on tail between henley block and main (import) meter.

Z

energysavingexp

my device is a photo electric switch that operates a ssr (solid state relay)
the photo cell looks at the led on the import meter that flashes when inporting and is constantly lit when exporting
it ignores the flashes and when it see the light for more than 10 seconds it turns the relay on as soon as the light starts to flash (importing leccy) the relay turns off

energysavingexp

noncom wrote: »

There are electronic gizmos available which can monitor the generation/export/import of your house, and divert power to a selected circuit only when excess power is being generated. However the cost of buying and installing these devices (as of a year ago when I investigated the same question) makes them uneconomical for domestic systems.

hi can you give me more info on the gizmos that you say you can buy im intrested in lookin them up and finding out how they work can you please tell me about them or gie me a link

thanks

noncom_2

http://www.coolpowerproducts.com/uk/emma-sp15.html

zeupater

energysavingexp wrote: »

my device is a photo electric switch that operates a ssr (solid state relay)
the photo cell looks at the led on the import meter that flashes when inporting and is constantly lit when exporting
it ignores the flashes and when it see the light for more than 10 seconds it turns the relay on as soon as the light starts to flash (importing leccy) the relay turns off

Hi

What delay circuitry have you got in place to stop the relay constantly cycling ? ..... If household usage is 100W and generation is 110W you will be exporting and the circuit will switch the load on resulting in a usage of say 1100W (with a 1kW immersion heater), which causes the import meter to flash ... which turns the relay off ... which causes the import meter's LED to constant state, and 10 seconds later it all starts again .....

Z

energysavingexp

zeupater wrote: »

Hi

What delay circuity have you got in place to stop the relay constantly cycling ? ..... If household usage is 100W and generation is 110W you will be exporting and the circuit will switch the load on resulting in a usage of say 1100W (with a 1kW immersion heater), which causes the import meter to flash ... which turns the relay off ... which causes the import meter's LED to constant state, and 10 seconds later it all starts again .....

Z

yes you are right but it is only connected to a 200w towel rail and it switches on at about 9am and tends to go off at about 4ish
and it goses off when i turn on the kettle or oven etc

most days when its dull so far it is producing about 800w
so it does not seem to cycle all the time

if i had it connected to the 1kW immersion heater yes it would be cycling all the time.

i have a bank of ssr's connected to different things so i can decide what comes on ie: in summer i can have say 3kw's of devices turned on and as winter aproches i can turn things off so lowering the demand so when we had the nice weather 2 weeks ago my 1kW immersion heater was connected and my towel rail and some othe r things.
last week only the towel rail was turned on

today ive had my towel rail and 1kW immersion heater on its now 3pm and its still exporting with both of them on so no cycling yet today. will need to turn heater off soon though.

ideally i would like to make a device that could mesure the amount of export current and turn on the different relays automatically
as the export increases.

sofar today my bathroom is nice and warm and my 300 ltr water tank is now at 43c

just checked the meter and its not imported any leccy today:j

pv produced 7.57kwh today