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Originally Posted by E350
I wonder if your solar is actually truly topping off your house battery or it is only fooling you into believing that it is...
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Are you addressing me? If so, I'm confident that my solar setup is keeping my house batteries up. I have three+ methods of keeping track, and they all basically agree.
1) Smart Gauge battery monitor. This gives a SOC that is based on thousands of voltage readings plus an algorithm It also just reads voltage.
2) Victron battery monitor. This is a coulomb counter type monitor, so the SOC can be inaccurate in certain situations. I mostly use it to see what's going in and out (it's great for that). Also shows battery voltage.
3) Solar controller display shows voltage, and also keeps me apprised of the charging voltage and stage, temperature of battery and controller, and how many amp hours came in.
I trust #1, but I also verify. One way I verify is a voltage reading after the batteries have been at rest (no charging or discharging) for around 12 hours. I am able to shut off all my loads when I want to check.
With few exceptions I'm up between 12.8-12.9 volts when I measure and the gauges agree.
The other way I verify is to keep track of how many amp hours go out, and how many come in. I have a pretty good idea of what to expect, so if something seems "off" I am likely to notice. I know what the refrigerator draws, what my laptop draws, what the fan draws, etc. I don't run that many loads, and I guess I just mentally keep a running tally almost without thinking about it. Probably from years of living on a boat without being able to afford (or have room for) even 200 watts of solar, lights weren't LED, etc.
For example yesterday: I know the refrigerator probably had around a 30% duty cycle (around 30 amp hours; it's not hot here), I charged my laptop once (around 6 amp hours), and I ran an LED light for four hours (2 amp hours), and I charged my phone (not sure what that takes, although not much). The solar controller's tally for the day was 38.x amp hours. So then it makes sense to me that the batteries would be back to 100%, because it's pretty simple math (and the various monitors agree).
Is there any reason you would suspect that 200 watts of solar wouldn't be able to put back 35-40 amp hours in a day? I have taken over 50ah in a day, but usually it is much lower simply because the controller will only put in what the batteries need and I don't usually use that much in a day. The high number days were after it had been cloudy previously, plus I was using a bit more power. If you have a setup that isn't working well (with around the same loads and same input), I would check for voltage drop, and/or the settings on the charge controller. I helped a friend re-do his system, and without really realizing it, he had over 20% voltage drop after the various "legs" were tallied up. Ouch! We took care of that, and a few other things (better settings on the charge controller), and the panels that were not quiiiiite enough before are now doing a good job.
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Not that I have the ultimate system by any means, but my needs are relatively small. That makes it a relatively easy task to keep up with them. I am confident in the fact that (so far) the solar has been keeping up fine.
One other thing is that I somewhat actively manage my power draws. What I mean by that is if it's a sunny day, like today was, and my batteries are topped up early in the day, then that's when I break out the Maha charger (charges AA and AAA batts via 12-volt hookup), my Jetpack, the phone, and anything else that needs to be charged. Otherwise, once the batteries are topped up, any potential incoming solar power will go to waste. This is somewhat like having a "load" hooked up to use excess power, only instead of hooking up the load terminal to a water heater or etc., I just manage it on my own, "manually," and use it for whatever might need charging. Not that I couldn't do these things at night from the house bank and then let the solar put it back the next day, but hey, the sun is out today and who knows, tomorrow it might not be. Why let it go to waste.
Everyone is different. The buddy I mentioned has 500 watts of solar, and it's *just* enough. I don't know what I would do with that much power. To each their own.
Sorry for the DC tangent - I don't really use much AC power, so not able to contribute much to the thread topic of 120v AC from a car alternator.
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