Energy Matters Forums

[Warpspeed]

You guys are doing all this the hard way.

The simplest way to make a system that can NEVER feed anything back into the grid is by using a grid powered rectifier and dc link into your system. Its simply impossible for a rectifier to feed anything back the other way.

All you need is to feed the dc output of your rectifier into your solar panel circuit through a diode at a suitable voltage.
At night the solar controller or inverter will think the solar panels are still working, but at an unusually low output voltage.

During the day the solar panel voltage will be much higher than the rectifier voltage, and the diodes in the rectifier will not conduct.

On a really crappy cloudy day, the solar panels will do their best, but any peak loads will pull the voltage down to a point where the rectifier will source whatever extra current is required to support the load.

At sunrise and sunset, the changeover form rectifier to solar and back again will be gradual and seamless.

Unfortunately I cannot post a diagram, but the idea is simple enough. I have be doing this myself now for a couple of years. My smart meter just shows power consumption (from the grid) dropping to zero in the morning and staying at zero until late afternoon. I have no battery, still reliant on grid power at night at this stage, although that will soon change.

[australsolarier]

warpspeed,
very few people can design and put together the system you have. i suspect you are the only one on the planet having the system you have. now i have a certain admiration for that fact. but you cannot expect that people rip out their grid feed system just to not feed in.
besides you are missing the point altogether. we are not worried of feeding back into the grid. we want to use that excess for ourselves. the simple fact is that there is a big difference between feed in and drawing from the grid, money wise.
i understand you like to talk about your exotic system. but i am not sure it is a solution to the thread here.
just saying

[Warpspeed]

The title of the thread says export prevention.
Ok I will shut up and go away.

[Tracker]

The title of the thread says export prevention.
Ok I will shut up and go away.

Indeed your concept would prevent EXPORT but while that is the hope, it is not the real motive.....
The desire is to USE, Completely Use, all the power available on my side of the main fuse..
..
I can't see your system using every joule of energy on site.
The Catch Power device results in no export for site and no wastage. And no battery.....

I suspect it is the cheapest energy storage on the market..
You just need a hot water tank..

[Tracker]

..
And yes - if the HW reaches cycling. Then the excess power will be exported..
unless. The "thermostat" includes a change-over contact that could divert excess-excess power to another storage device..
But the reality would suggest that SO MUCH energy can be stored as Hot Water, that the cost of extra storage would be a waste..
..

[Tracker]

..
Been using the Catch Power Device for some weeks now..
Seems to be doing just what I anticipated, with very little power going to the GRID, and my excess power being stored as a real value commodity of HOT WATER..
(again - I cut off the Town Gas and converted to LPG, to give US the control of those costs..)
..
The 160L HW-Tank is heated to about 75c each day
A Thermo-Mixer modulates the outflow to about 40C to the INSTANT LPG GAS Heater
The LPG Heater heats to 50C to supply the house..
..
The believed advantage with this is that we have a constant 50C supply temperature, without unpredictable changes that come from the instant gas device turning on and off, as they get confused by HOT water inflow..
Gas usage is greatly reduced as it is only topping up the service temperature ie.. 40 to 50C compared to say 20 to 50C for the day's usage, previously..

I think that I worked out that we are storing about 9KWH a day..

I can't say that it is great value for the cost (being Resistive HWS plus Catch-Blue power diverter..)
but it is massively cheaper than a battery storage device, and the bidirectional conversions losses..
..
Looking forward to the next bill to see how it has changed..
..
.

[Tracker]

..
PS - We are trying it now with the GAS-BOOST off completely..
Warm Showers but not toasty hot.. BUT IT'S FREE..
The warmer winter Sidiney days are sufficient to keepthe two of us supplied with Hot Water..

Can't really say that it is FREE, as there is the foregone income from Grid Feed and that is 12c a unit..

so, given that the OFF PEAK (cheapest GRID power) is about 18c and they will only pay me 12c, then I am still ahead..

I THINK...
..
.

[Tracker]

..
Hmmm.. Glorious Weather ATM..
Half way through the Solar Day , and the Hot Water is fully heated.. ie. my bloody power is going to the GRID..
..
So solar-diversion is only as good as your ability to store it..
(Not that such is ANY different to charging a battery)

Plan-B - to detect when the HW has reached temperature and then find another "Storage Device"
..
.
Plan-C - current water temperature - 75C - I wonder if there are higher temperature thermostats..?????

[davidg]

They used to be able to set to 80C and of course that's just hot enough to use directly for a cuppa.

[Tracker]

..
So, we have been using the Catch Power for some time now, and we are very pleased with the result..
Easily the cheapest "power storage" you will find..
Only catch is that whilst it saves lots of money, you can't run your lights at night..
..
We have found that we just let it run with the gas boost turned off.
As we run on LPG, the refile are far less frequent ..
..
So still keen on this device..
..
.