Added 2nd solar panel, but no power increase

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KennyM

221 posts

Master Geek
+1 received by user: 10

#847328 30-Jun-2013 09:55

Hey, thanks for all the help guys.

Its 100% clear that I was/am measuring the amps the wrong way.

Did I cook the meter? no, I dont think so, still seems to be working fine.
Did I have one of the plugs in the wrong place - yes

The system was designed for 5 solar panels, I have a prostar 30amp solar controller - so the extra amps from the 2nd panel is well within tollerance (I spent the extra on a larger controller at the start - I just couldnt afford all the panels to go with it)

After reading the above comments, perhaps I have connected it correctly, and its just me reading it wrongly.
I have checked the power meter on the battery, and the voltage does appear to have gone up sharper after the 2nd panel was put on yesterday. now that theres enough information to actually see the trend.

The graph shows the last 4 days of data. couple where I used it a little, then not at all, then yesterday when I put the 2nd panel on - and drew a lot of power out of it.

I installed the meter that this graph came off as per its instructions, voltage is measures fine, but it will only show amps drawn from the battery, NOT amps put back into the battery via charging...something I also didn't realize when I got it.

If I was to buy something like this:
http://www.jaycar.co.nz/productView.asp?ID=QP5588&keywords=ammeter&form=KEYWORD
And have it inline between the solar panels and the controller, would it give me a true reading of the current amps??
I now understand it would show amps going past only - ie if the battery was full and nothing being drawn it would show lesser use.

grant_k

3539 posts

Uber Geek
+1 received by user: 124

Trusted

#847349 30-Jun-2013 11:03

The Jaycar meter you posted the link to will give you an instantaneous current reading, but so will your multimeter when correctly set to the high current range. Most digital multimeters have a 10A or 20A range, but you need to move the banana plugs into the correct sockets in order to use it.

To be honest, I think you are taking the wrong approach here. What you need is to know the total Ampere Hours that are delivered over the course of a day, week or whatever. In mathematical terms, that is calculated by integrating the area under the curve. It looks as though your existing meter is doing that to produce the "staircase" pattern showed by the brown trace.

Why not hook your existing meter into the leads from the solar panels to the charge controller and see what it shows?

If it gives useful information when connected in that position, maybe you could buy a second meter and always have one showing the charge current with the other showing the load current. The high-end brands of charge controllers like Outback provide all this information via a front panel LCD and a web page. But you'll have to pay a lot more for them than your Prostar would have cost.

KennyM

221 posts

Master Geek
+1 received by user: 10

#847944 1-Jul-2013 22:14

Just an update, I actually had time to use my computer yesterday (and thus flatten the battery)

Updated graph shows yesterday sitting there charged all day,then me using it, and todays recharging - which was mostly sunny all day, but the blip must have clouded over (I was out of town)
It wouldn't have charged that much if it was only charging from one panel.

So ive learned how to measure amps.

Thanks for helping out.

As for moving the meter, ive thought about getting another shunt and moving it, shall wait and see.

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