Solar at its Best

Solar isn't for everyone. I've talked to Roy about his set up and between limited roof space and limited hours of sun he can't get what he needs out of solar. My set up could easily do it but it's portable and sets in the sun tracking all day if need be.

Dave - I'll shoot you an PM if you don't mind ... Be interested in what you have to say...

Roy Ken

A 130w 12v panel has an Isc of approx. 8.2a, which you should get when the panel is aimed right and the sun is high enough, in blue sky.

That contraption in the photo should be pulling approx. 16a for much of the day in sunny conditions if twin 130s, but I agree, they appear to be twin 230w and he must have MPPT for them as well.

It may be helpful to look at an example where we are doing 50-90s but with solar to extend the time between gen recharge times. (We don't have quite enough solar to keep up with usage)

In this case, we have a 490AH bank and one 130w panel tilted at a fixed tilt angle, but in a swivel contraption, so it is a manual tracker of a type. It gets a daily AH haul of 90AH on a sunny day similar to what a 200w array lying flat would get.

I don't know our daily AH usage, it varies from 100-50 depending on all sorts of things, mostly closer to the 100. OK, so the way it went recently, starting with close to full batts on 30 Aug.

Mixed weather so 3 Sep after four days morning 12.1v, did a gen recharge to 90%,

Next was three mostly cloudy days, and 12.1v on 6 Sep. Gen to 90%

Then the sun finally came out for some more summer-like weather and
today 14 Sep hit 12.1v after eight days.

The trouble with this routine of solar assist to stretch out the time between 50-90s is you can spend a week, or who knows how much longer, with the batts riding between 12.3 and 12.5, and this isn't great for sulfation concerns.

-With two 130s we would be mostly gen free but two cloudy days in a row would change that.

-Went most of mid-April to mid-August with only a few gen recharges when we had more solar than now.

-Also we were doing more like 85-97s so the batts were happy to get almost full fairly often.

-To get right full we would have to do the split bank trick to equalize half the bank at a time. No big deal as a monthly chore.

At no time is it safe to have no gen available as a back up where you are in a place that can get cloudy for a couple days in a row, with a normal RV solar outfit of a couple panels on the roof.

Where solar is good, often it is also hot. So you see all these plaintive threads about how to run the air conditioner with no gen and just solar. Not my problem, thank goodness. :)

BTW, RJ said those panels were 130W each unless I misread him. Neat setup though.

scroller95969 wrote:
How can you tell they are 12V panels? It looks like to me that the two panels put together are wider than the height. Two 12V 140 watt panels side by side would be about 6" narrower than the overall height making it a 280 watt system. Two 24V 235 watt panels side by side would be about 15" wider than the overall height making it around a 470 watt system? Just an observation but I'm sure I messed up on my math somewhere.

Where was it ever said they were 12v panel ??.

RJsfishin,

Very cool setup!!! With the help I got from the people on this forum we have only used our generator a few times in the last couple of years for AC only. The solar system (705 watts) and battery bank (6-six volts-690ah) has made life easy off the grid. :)



Still have room for a couple more panels.

Wish I had your roof space Rick!

Sorry, being a relative newbie in solar I wasn't aware that 130 watt panels came in 24 volt so I was assuming they were being referenced to be 12 volt panels.

RJsfishin wrote:

scroller95969 wrote:
How can you tell they are 12V panels? It looks like to me that the two panels put together are wider than the height. Two 12V 140 watt panels side by side would be about 6" narrower than the overall height making it a 280 watt system. Two 24V 235 watt panels side by side would be about 15" wider than the overall height making it around a 470 watt system? Just an observation but I'm sure I messed up on my math somewhere.

Where was it ever said they were 12v panel ??.

The basics of solar tracking are simple and inexpensive. Making it strong and stable enough for the windage on top of an RV could be challenging. Below is my post from several years back.

I thought that it would be interesting to share ideas on solar panel trackers, especially those that can be used on a RV. The picture below shows a DIY one that is simple and inexpensive.
1. This is a single axis E-W tracker.
2. The elevation is set by manually adjusting the frame.
3. The frame lays flat under the ATVs for transport and the panel is stored on the bed. Setup takes about 15 minutes.
4. The tracker waits for sunrise and then tracks the sun moving the panel every 5 minutes.
5. At night time the tracker returns to the east and waits for the sun.
6. The panel is in the morning position and will rotate CCW to the west.
7. On the lower left of the frame the servo that changes the panel angle is visible.
8. The controller is shown on the lower right corner of the panel and it’s mounted on the panel inside a glass or plastic bottle.

The frame was designed for two panels which is why it's larger than necessary. The owner found that he got so much power from one panel that he didn't need a second panel. The controller can be purchased from Red Rock. Two LEDs about a inch apart detect the difference in light from the sun and the electronics instruct the servo to position the solar panel. Note: When light shines on a LED it produces a voltage. Many variations of this controller are available including two axis versions.