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Solar related tips  RSS feed

 
Posts: 20
Location: British Columbia, Canada
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This thread is about useful tips relating to; solar panels, charge controllers and batteries. It is NOT about complaining. I realize it can be hard to raise this topic without relating problems that can be encountered when dealing with this subject. And if someone wishes to start a topic for complaints, I'll likely chime in.

That being said, I offer the following words of wisdom and experience.

Just about two years ago, I bought a couple of deep cycle batteries from Napa to replace the Trojan brand ones that came with my old travel trailer. The Trojans were previously charged off the tow vehicle but having sat for a couple of winter months, they had bloated and shorted out a couple of cells each. Hindsight is great, but foresight would of been more help, as I should have replaced with the same brand of battery.

So I ordered the biggest panel I could afford, a 100 Watt 12 Volt that came with a 12v/24v, 20 amp PWM charge controller. Fast forward past some issues with the batteries.

If not for the issue with lack of sunshine, I'd say all is well. Despite what people said about cheap Chinese stuff, the panel has worked just fine, survived s few hail storms and wind storms with no noticeable blemishes. And i don't think the bouncing around on my little trailer has helped preserve it.

Likewise withe the charge controller.... But...

Had I known then, what I know now. I would have bought a 30 or 40 amp MPPT charge controller and a higher wattage panel, (at least 200 watt), but only one battery, (about 110 amp hours).

Then when I had the cash to spare I would have doubled up on what I had, running each set of panel/controller/battery separately. I would have the load connected through blocking diodes, allowing proportionately equal draw on each system.

TIPS:

1) try to get batteries with an amp hour rating that's at least double your panels wattage rating.

2) Try to find a MPPT charge controller. It will convert slightly more of your panels output into stored usable power in your battery. It also works better than the PWM type in cold temperatures.

3) For small to medium sized systems, try to use a charge controller for each battery.

Reasons:
A) Despite what the pro's say, its virtually impossible to find two or more batteries to use for a battery bank that are and will continue to be exactly the same after years of use. And you can be sure that the weaker battery will keep all better ones connected with it from charging properly.
B) Better charge controllers have a remote temperature sensor to tell the controller if a battery is getting hot, (I guess). Having more than one battery means likely different temperature readings that could mislead the controller.
C) Likewise with the controllers ability to properly detect the batteries SOC (State Of Charge). With more than one battery the controller will only detect the lowest voltage in a set of batteries and charge all the batteries connected to it based on that information.

4) Reason why solar doesn't work as well in northern climates at this time of year. Its winter. Which means shorter days and less sunshine on panels, due to the angle of the sunlight in relation to the earths axis. What can be done about it? Try something shiny to reflect more light onto the panel, (like a mirror). Google it. You'll see.

More to come.

Keith.
 
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