Solar question

laknox wrote:
So, from what some of you are saying, a higher voltage panel is better than a lower voltage one; correct? With a good controller, I could use a 24v panel and it would step it down to 12-15v to the battery?

First off, 24V panel is a poor choice for portable. They are all 220W or bigger, weighing +40 lbs, and 65x40" size makes it really awkward to handle.

Q. 1) They are better for big arrays because they are cheaper per Watt than 12V panels, and easier to wire, having lower current for the same wattage. Plus, MPPT controller will add some efficiency until the weather gets too hot - then panel efficiency drops and overall output can be lower than if you were using 12V panel.

Q. 2) Not with a "good", but with "MPPT". With 24 panels you have to use MPPT. Any controller should better be "good", if you care about your batteries. There are poor quality MPPT out there as well. Yes, it will lower the output volts and boost the amps by the same ratio.

Better? I'd say different. At some large size system it can make sense to go with higher voltage panel(s) and a MPPT controller. Many quality MPPT controllers cost more than a small solar PWM system.

Yes, an MPPT controller forces the panel(s) to operate at peak power and internally transforms the power to ~battery voltage for charging.

So, from what some of you are saying, a higher voltage panel is better than a lower voltage one; correct? With a good controller, I could use a 24v panel and it would step it down to 12-15v to the battery?

Lyle

red31 wrote:

Hard wire controller and use MC4s to make connection or use longer landscape wire wired with some sort of plug near controller.

I would hardwire only the output cable to controller.

For input I would attach to controller a short piece of MC4 (cut in half, bare ends to controller), to connect to corresponding MC4 of the panel. It is important to break the circuit btw controller and panel when controller is not connected to battery.

For output he can use a landscape cable or any other #10-#8 cable with whatever disconnect he'll put on the battery end. He could even use car jumper cable with crocodiles, on a calm day and if there are no dogs, distracted children etc running around. On the controller end the crocs would be cut off, to hardwire it to controller AND an inline fuse should be spliced into Pos wire there.

laknox wrote:
Remember, all I'm trying to to do is to extend my normal stay by a day or two without having to run my batteries way down.

For playing catch-up all the time camping no controller is needed, controller prevents overcharge. For storage a controller is needed.

$90 grape 100w 12v panel and 12g (20-50') landscape wire from home depot.
Add on a $55 grape 40A-BT controller and more landscape wire.
or get the $160 100w kit that includes tray cables with limited distance MC4 wire that ya cut in half to attach to panel/controller (assume this is 15' so cut in half is 7.5', too short!). Another 15' of MC4 wire is ~$22. Add short MC4 to bare wire conversion wire ($12) to each wire to connect to panel. (kit & assesories = ~$200

Hard wire controller and use MC4s to make connection or use longer landscape wire wired with some sort of plug near controller.

Use in storage/home as battery maintainer.

pianotuna wrote:
https://www.solarblvd.com/products/seraphim-solar-usa-340-watt-24v-72-cell-solar-panel-mono-ul-grid/ $175 usd

Best to pick it up from them and have a nice holiday trip.

Woo Hoo thats a 72 cell panel. If he is doing portable that panels huge.

Is the OP doing portable or mounting on roof? I read portable but not sure what the OP has now that he is adding???

I agree with the 24 volt panels and MPPT, but thats just my preference.

My 2-60 cell panels are big (560 watts) and I use them as portables, but need to be lugged around in camper or bed of pickup.

My opinion is buy a mppt 40 amp controller. You will not need to buy it again down the road when you expand.

This is whats recommended. I use 2- 280 watt panels with this type controller.

https://www.amazon.com/Controller-Negative-Grounded-Regulator-Charging/dp/B077HQPV1Y/ref=sr_1_7?ie=UTF8&qid=1525349380&sr=8-7&keywords=epever+40A+MPPT

And two of these would be good.

https://www.solarblvd.com/products/german-solar-270-watt-24v-60-cell-solar-panel-poly-ul-listed/

Then get a bigger inverter and add outlets for the camper. Youll boondock with no issues, and your limit will now be your tanks.

Thats about $600 bucks worth of stuff.

https://www.solarblvd.com/products/seraphim-solar-usa-340-watt-24v-72-cell-solar-panel-mono-ul-grid/ $175 usd

Best to pick it up from them and have a nice holiday trip.

pianotuna wrote:
We have a member (Jim in Denver imms) who had a poly and mono panel from the same maker. The poly consistently outperformed the mono.

Itinerant1 wrote:

Almot wrote:

Monocrystalline is not better than Poly.

Other than poly being cheaper in price. Why is it when searching the question of which is better mono keeps coming up as being better? :h

I suppose if one person tested it it's possible. Possibly cooler temps during the test in Denver? But seems strange from research that monocrystalline panels
supposedly perform better in higher temperatures, though there will only be marginal efficiency differences.

Local prices, no shipping for the panels or Tracer, Amazon.ca for the Grape: (prices Can.)

320w poly for $289 plus a Tracer MPPT $140 = $429 (~$330 US)

160w poly $249 x 2 = $498 plus Grape 40 at $84 = $582 (~$448 US)

http://www.wegosolar.com/categories.php?category=Solar-Panels

We have a member (Jim in Denver imms) who had a poly and mono panel from the same maker. The poly consistently outperformed the mono.

Itinerant1 wrote:

Almot wrote:

Monocrystalline is not better than Poly.

Other than poly being cheaper in price. Why is it when searching the question of which is better mono keeps coming up as being better? :h