Oct 042018

So, I’ve been running the Redarc controller for a little while now, and we’ve had some good days of sunshine to really test it out.

Recall in an earlier posting with the Powertech solar controller I was getting this in broad daylight:

Note the high amount of “noise”, this is the Powertech solar controller PWMing its output. I’m guessing output filtering is one of the corners they cut, I expect to see empty footprints for juicy big capacitors that would have been in the “gold” model sent for emissions testing. It’ll be interesting to tear that down some day.

I’ve had to do some further tweaks to the power controller firmware, so this isn’t an apples-to-apples comparison, maybe next week we’ll try switching back and see what happens, but this was Tuesday, on the Redarc controller:

You can see that overnight, the Meanwell 240V charger was active until a little after 5AM, when my power controller decided the sun should take over. There’s a bit of discharging, until the sun crept up over the roof of our back-fence-neighbour’s house at about 8AM. The Redarc basically started in “float” mode, because the Meanwell had done all the hard work overnight. It remains so until the sun drops down over the horizon around 4PM, and the power controller kicks the mains back on around 6PM.

I figured that, if the Redarc controller saw the battery get below the float voltage at around sunrise, it should boost the voltage.

The SSR controlling the Meanwell was “powered” by the solar, meaning that by default, the charge controller would not be able to inhibit the mains charger at night as there was nothing to power the SSR. I changed that last night, powering it from the battery. Now, the power controller only brings in the mains charger when the battery is below about 12.75V. It’ll remain on until it’s been at above 14.4V for 30 minutes, then turn off.

In the last 24 hours, this is what the battery voltage looks like.

I made the change at around 8PM (can you tell?), and so the battery immediately started discharging, then the charge-discharge cycles began. I’m gambling on the power being always available to give the battery a boost here, but I think the gamble is a safe one. You can see what happened 12 hours later when the sun started hitting the panels: the Redarc sprang into action and is on a nice steady trend to a boost voltage of 14.6V.

We’re predicted to get rain and storms tomorrow and Saturday, but maybe Monday, I might try swapping back to the Powertech controller for a few days and we’ll be able to compare the two side-by-side with the same set-up.

It’s switched to float mode now having reached a peak boost voltage of 14.46V.  As Con the fruiterer would say … BEEEAAUUTIFUUUL!