Solar Produceing at night. Wrong reading?

Submitted by Guest on Wed, 18/09/2013 - 22:15

Hi i have a 10kw array installed and have the emon tx and ras pi set up.

at night the solar says it is still producing 400w? can i fix this?

i know at night 40w or so will go back to the inverters to power them but not 400w surely

any ideas or input process i can do to fix this?

Cheers sam

Re: Solar Produceing at night. Wrong reading?

Submitted by Robert Wall on Wed, 18/09/2013 - 22:41.

That does indeed sound wrong. You need to find the source of the problem.

Firstly, which sketch are you using in your emonTx? Are you monitoring the mains voltage and is the c.t. we're concerned with on the PV infeed? What is the current rating of your c.t.? Have you calibrated your voltage and current readings?

The 400 W could be due to noise pickup in the analogue front end of the emonTx, though 400 W does seem excessive. A value in the low tens of watts can be expected if you're not measuring voltage and calculating real power, and less if you are.

The first thing to establish is, what happens if you unclip the c.t. from the cable, does the power fall to a few watts jumping about randomly?

Re: Solar Produceing at night. Wrong reading?

Submitted by goldpower (not verified) on Thu, 19/09/2013 - 04:13.

Thanks for your reply Robert

I have found that it was reading over all the time by 300w-350w so i added a process to -350w and it was reading better today. i will have another look tonight and see if it drops back to around 40w like i would expect it to.

Will let you know.

cheers

sam

Archived Forum