$.80 solar panels
A while back, maybe months, maybe last year, someone posted a link to solar panels for 80 cents per watt. I've tried searching but can't find it. I've also looked around eBay and Amazon and can't fi...
Forum Discussion
EldIr wrote:BFL13 wrote:
There is a saving in solar where the controller only has to step down to 24v instead of 12v to run things. So a 24v inverter on a 24v battery bank supplying 120v has that advantage. Going to 48v even greater. You lose that when you choose 12v systems that need the controller to step down to 12v.
It would be interesting to compare the savings using 12v direct rather than bricks taking in 120v from inverter with the solar savings from only having to step it down to 24 or 48v.
The Rv is tied to 12v by the fridge and furnace control boards needing 12v even though they run on propane. Otherwise, you could do everything with 120v.
A cabin can have 120v for res fridge and heaters, so no more 12v.
All appliances are propane. Heat is wood and propane. It would be interesting to do the math, but that's too much for my head right now. Even our 300w inverter wastes battery and when we step up to 1000w, it will waste more. That's why we like to run things on 12v. I'd be curious to know if the inefficiency of using a 12v controller is really more wasteful than running an inverter.
24 volt panels will work happily with 12 volt batteries but of course you need an MPPT controller. When connecting the controller you connect the the batteries first, this tells the controller that it needs a 12V output and will convert the incoming voltage to suit 12 volt batteries. It does the same thing with 12V panels, making sure that the battery voltage doesn't exceed say 15 volts. Using 24V panels and an MPPT controller will allow lower gauge wire (cheaper) and/or lower losses and the panels are cheaper too. An MPPT controller will usually put more amps into the batteries as well. In a cabin, that is what I would do.
