energy meters on solar not accurate

[dave462]

hi i`ve been using a bg energy monitor for aweek or so,however it reads the output of my solar panels sometimes eg panels producing 2.5kw meter says 2.8kw (300w house load) at other times it doesnt.i dont understand how the ct coil is getting confused any ideas.
also i`ve found a supplier of low watt immersion heaters is there anything on the market that monitors load vs energy produced and can sw a load on when production is say 1kw (500w house load + 500w heater) and will sw load relay off if production drops below 1kw
thanks dave

 

[BruceB]

Some SMA inverters have a function built in that does some of that. They call it multi-function relay and it is programmable.
Regards
Bruce

 

[Worcester]

The energy monitors working on the loosely fiited clamp are NOT accurate, they give an excellent guide, just don't expect the units on them to match up with the generation meter.

They are great for monitoring consumption / generation relatively, just don't take the number literally.

 

[Graeme Harrold]

Some SMA inverters have a function built in that does some of that. They call it multi-function relay and it is programmable.
Regards
Bruce

Thanks for that, never gave the relay a second thought. Since I have delved into the SMA website and have done some reading up on its functions and switching a load is now on my hit list. Now just need a little help from and electronics boffin on half wave rectification for an immersion heater as this may be the simplest way to reduce a 3kW element into a 1.5kW thus dumping the excess into the water heater. Is the diode option viable and my guess the answer will come from Worcester

 

[dave462]

i`ve found a company that sells 500w 750w and 1kw immersion heaters of various lengths which should prevent the problem of rectification unless you only heat your water via an immersion

surejust.co.uk is the company

hope this helps

 

[Graeme Harrold]

Thanks, but if I can derate with a diode it saves draining and emptying tanks to change the element. A £1 diode should do it.

 

[Worcester]

Graeme, takes me back a bit to electronics, and sorry, I'm not the best palce to adise you, though I guess you want something like this 3A Silicon Rectifiers : Diodes : Maplin (It'll cost more in fuel to go fetch it! ) - check the specification page, for the

1N5404

400V

280V

400V

or this 6A Silicon Rectifiers : Diodes : Maplin and once again from the spec page

P600J

600V

420V

600V

 

[Graeme Harrold]

Thanks, found a 10A 400V diode, so man enough for the job, just wanted to chech that half wave rectification is the way ahead to fool the system into powering a 3kW heater with 1.5kW. That way I can set the relay to kick in at say 1750W to heat the water

 

[whlphil]

These guys make some interesting monitoring and load switching kit in simple plug in form, nothing as fancy as full on tinkering ;-) just plug in switches!

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