I wish it was that easy, generally it's not. The issue is that a system produces X amount of kW's or watts at any instant.
Lets say for this example, 6kW's is being produced and it happens to be clear day your heat pump can use say 2kW's continuous at any instant, your background loads are say 1kW so you are using for a period of time upto 3kW's over a period of an hour which equals a total of 3kWh's consumed with the extra being exported to the grid. That's great but you had another 3kW's that could have been used more effectively for something over that same period of time which when the time constant is added equals 3kWh's.
The issue is if you don't use it instantly then it gets exported to the grid, motors are the most difficult to manage because they are inductive devices which unless they able to be controlled with variable frequency really hate variable power input with a passion, mains powered heat pumps dislike a highly variable power input, there simply not designed to cope with it. As for charging an electric car or similar again much the same issue exists with them, for different reasons. Solar is highly variable power source, at any instant the sun can go behind a cloud and the systems output can go from the say 6kW's to virtually nothing in fraction of second. That's the reason why batteries added into a system can be such a big deal, they will absorb excess power depending, then provide it when the sun is suddenly obscured for a period of time and so on as well as being able to provide power when the sun is not available (night time). To be able to store enough energy and have a good life from a set of cells requires a considerable investment in a battery (multiple cells connected together) that is/are designed to cope with high cyclic use and a controller for power to and from them. I generally use Selectronic Battery inverters because they are highly versatile and I can use the digital control switching to turn on and off various loads based on SOC of the batteries or the voltage or other criteria.
TA and his bunch of nutty loops didn't do us any favours with an utter lack of vision that has been about for the last couple years, hopefully we'll see a good change in policy at some stage in the not too distant future, that forces distributors to embrace, rather than stymie, going forward. We'll have to wait and see. I've been leveraging batteries myself for a quite a while, since well before distributors made things so much harder. I've also installed intelligent battery systems and retrofitted battery systems for a number of clients as well over the last several years. They can add considerable savings, but only if done and programmed properly otherwise it becomes very expensive with no savings at all. Good battery solutions are a long term investment. The imagined price reduction of batteries won't occur for a longtime if ever particularly with the AU dollar exchange rate being where it is and not likely to improve anytime soon.
Posted Monday 21 Sep 2015 @ 3:54:39 pm from IP
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