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...my diversion load is a 500hz 12v signal that goes to a ssr and dumps the 48v battery voltage through an approx 10ohm resistor (water heater element) I assume the 48v comes out of the ssr at 500hz, not exactly as dc.

What if all you did was add a very large capacitor (or a few of them) with a resistor in series to limit charge /discharge amps between positive and negative between the ssr and the micro inverter? Would it smooth the dc power enough that the micro would be happy? Would it store enough that when the mppt swept up it would drop a bit of amps and mimic a solar panel?

It sounds like a thread hijack when I read through it, but it kind of applies to sparweb's setup too.

Spar, that link you posted is a cool and useful electronic circuit simulator. Thanks.
I’m going to play with that a bit tomorrow.

Ed

Quote from: bigrockcandymountain – on January 24, 2026, 05:44:46 AM

What if all you did was add a very large capacitor (or a few of them) with a resistor in series to limit charge /discharge amps between positive and negative between the ssr and the micro inverter? Would it smooth the dc power enough that the micro would be happy? Would it store enough that when the mppt swept up it would drop a bit of amps and mimic a solar panel?

Funny you mentioned the SSR just when I was getting frustrated with designing my circuit with a MOSFET, and tonight I've been replacing it with a SSR.

I think I have the microcontroller signals figured out.  What's really bothering me now is that I've made some assumption about the inverter and I don't like the way things go bad if I am wrong.  I've been using Falstad's site to simulate this, and it suggests I will be blasting the 0.5 ohm power resistor with brief bursts of 90 amps.   Probably just something I have simulated wrong, but...

To your suggestion BRCM, yup, a big capacitor soaks up a lot of nuisance noise.  You just have to make sure it doesn't drown out the signal you want to measure.  Circuits that combine resistors and capacitors have a "time constant".  If the constant is long (in the electronics world 1 millisecond is long) then the time for the capacitor to charge up is longer than the time for a 1 kiloHertz signal to arrive, and you probably won't measure the signal.  On the other hand, if the capacitor is too small or ineffective, then the microcontroller is measuring pulses and it may pick up the pulse on the Hi during one reading, and on the Lo on the next.  From the microcontroller's perspective, the signal went from on to off, and in a sense, it would be right.  But in another sense it failed to detect what the power resistors are doing.  It missed the next Hi peak which has a different voltage than the last Hi peak, and that was the information it's looking for.  So there's a balance, when Goldilocks finds the right oatmeal.

Quote from: bigrockcandymountain – on January 24, 2026, 05:44:46 AM

It sounds like a thread hijack when I read through it, but it kind of applies to sparweb's setup too.

Nah, you're forgiven

Quote from: bigrockcandymountain – on January 24, 2026, 05:44:46 AM

...my diversion load is a 500hz 12v signal that goes to a ssr and dumps the 48v battery voltage through an approx 10ohm resistor (water heater element) I assume the 48v comes out of the ssr at 500hz, not exactly as dc.

48v/10 ohms = 4.8 Amps
60v/10 ohms = 6.0 Amps

Hmm surely you'd dump more than that?  I think your WT is bigger than mine is, and I need a 2kW diversion load (and I admit mine turns out to be only 1.8kW).  It may not matter in your case if you're using your batteries most of the time.