Quote:
Originally Posted by BillG
Well, I said it before, but will say it again. The number came from PVWatts. This is the gold standard tool, from the National Renewable Energy Lab, NREL. Since you used Sacramento, so did I. I don't think it is good policy to give a wild guess when someone asks for advice.
100 watts is fine for panel size if using an MPPT charge controller. Using a cheapo is fine, too, but he'll need at least a 130 watt panel for the same charging capacity. If he wants to charge his battery faster, simply pick a larger panel.
The charge controller should also control the lights - on at dusk, off at dawn or some user defined number of run hours. It should have a proper low depth of discharge protection.
Why mess with conjuring some electronic circuit and hacking a light bulb apart, when you can just use a 12 volt bulb?
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I didn't, I linked a 12V example. He doesn't take anything apart. The original bulb runs to an E26 socket which is 120V, so you need to include an inverter to 120v for your total cost.
NREL shows 5.8 to 6.5 for Sacramento. What did I quote from an alternate site:
"Using a yearly average, there are 5.38 daily peak sun hours across the state of California. This number is calculated for a fixed solar panel."
We can use MPPT but it adds equally to both analysis calculations, I didn't look back but I don't think sun hours is that critical that he needs MPPT but if he does he can substitute the module package with the CC for separates and include a cheap MPPT.
https://www.ebay.com/itm/100A-MPPT-S...DiFg:rk:7:pf:0
Please cite the cost of an MPPT CC that also controls external devices. I have expensive controllers here but they run into the hundreds of dollars.
Also starting small allows him to build to his needs. Over building leaves no reduced cost options. Look at the price your system will cost and now you want to add an MPPT with peripheral control?
He's not running an iron lung to save lives he's lighting porch light! You're up to several hundred bucks.