Classic 200 Conversion Efficiency

[rwsaustin]

Thanks Vic. I'm just guessing about the 120F module temperature. I need to measure it in full sun. I have an upstairs window in a dormer above the PV array, so I should be able to make the measurement without a ladder. Most summers, we get quite a few days over 100F, but it seldom reaches 105.

I think I'm satisfied that everything is performing about as well as can be expected. I have a spare PV module and room for it on my roof, so I may consider reconfiguring to 7 strings of 3 at some point in the future.

Robert

[Vic]

That temp value is just the Ambient temp of the air.

The NOCT rating is a fairly good value for cell temp,   just add for  your air temp at the temp  co of your PVs,  and  a bit  for possible 1 kW/sq meter,  vs 800 W.

Later,  thanks,  Vic

[boB]

So boB, your suggesting is to add a WB Jr. and measure the PV current with circuitry external to the Classic? I'll search the forum for this. Was your suggestion to try Hydro mode to stabilize the voltage or to find a better MPPT than the one the Classic found? By my panel specs, MPPT voltage should be about 150, by my Classic is pulling at 116V.

Robert

I thought you might already have a WB Jr. there.  Hydro mode just so the PV voltage stays constant.   But even doing things this way does not guarantee that voltages and currents are going to stay still even long enough to take a good measurement because clouds move.  Better if there are NO clouds at that time.  Also, your battery will want to be NOT charged so it can take the current...  That or have a steady current draw on the battery line.

Even when everything is stable, I use a camera to take pictures of the meters and measurements because if you write a voltage and current down, the others will change while you're writing.   That's what happens to me anyway.

[bee88man]

Robert, you aregetting some great help here on this board, we all are so lucky!!

Thinking about your thought to pull cooler air from the house made me want add somethings not said...
When pulling any volume of (cooler )air from house an equal volume does need returned or made-up.
Another thought is you wouldn't want battery off-gases circulated back into and throuhout living space.
You maybe already had all these thoughts, but anyways others reading may gain so insights by reading along.

And one more thought...you see correctly having that huge "heat-sink" in that concrete floor...keep in mind that hotest air lies up at ceiling...
to maximize heat-sink you might need to not let it happen passivlly.

Best of luck!!

[boB]

One instrument that the industry uses to measure efficiency is something like this...

https://tmi.yokogawa.com/us/solutions/products/power-analyzers/digital-power-meter-wt300e/

You would need two of them.  They are only around $2,000 or so each.   It just isn't easy or cheap to measure efficiency accurately.

[australsolarier]

my power room is fully air conditioned. if the lifepo4 batteries last just 10% longer, the capital expenditure has paid back in full. besides all the electronics is kept cool, 20C. the power room is also fully insulated, has concrete floor and brick walls on the two long sides.
a cold concrete floor does not cool a room. the cold simply keeps low. (maybe circulating the air with a fan might help a little bit)
and consider, your electricity consumption will go up and more charge controllers and more panels, more inverter conversion which only adds to heat. i estimate the electronics in my shed probably heats the power room at least 4kwh an average day.
the aircon also keeps the air dry. keeps out snakes and other vermin. it is more pleasant to work inside. the steady temperature make comparisons more reliable.

keeping the room at 20C also prolongs the lives of all them expensive electronic devises with all the caps in them. caps like a battery degrade much faster in hot temperatures. lithium batteries in particular do not like hot temps. it will certainly shorten their life.

i also have a computer fan underneath each inverter and charge controller. it will keep the devices that much cooler again and changing the fans in a midnite is a major operation. so the internal fans are only turn on as back up on extreme peak power situations.