Solar Panel deal

[scrubjaysnest]

Originally Posted by ShrimpBurrito

I love the idea of panels, and that's certainly the route I would go before ever getting a genny. But so far, we've never run out of power with our Trojan T-105s, even with generous heater usage.

Dave

We went from the end of April last year until the first part of September without shore power. With a single marine deep cycle, not best for the service, I swapped it out about every 7 to 10 days. I have a second I charge in the TV while exploring the back roads. With the temps last year an O2 cool fan ran almost 24/7. The other major usage was LED lights and the famous toilet. The heater was only run 3 times for about an hour a day. The solar panels are being added primarily for western trips like this year. East coast NPS and USFS campgrounds tend to be pretty shady. We don't carry a genny, just can't stand the noise of even a quite one.

I am using a morningstar ProStar 30 controller and am very happy with it. Has all the charge modes and as well as has the option of getting with built in meter. It is also nice as it has settings for three main types of batteries. I have no issue with sufficient charge voltage.

[scrubjaysnest]

Here are my test results of the solar panel set up we got. I replaced the 12 awg 30 ft run with 10 awg 22 feet. The Sunsaver 10 is mounted within a foot of the battery(s) and is connected with 8 awg wire. There is 3 ft of 12 awg from each panel to the so called combiner. The combiner has MC4 connectors and has two 1 ft pieces of 12 awg spliced, unknown how it was done, into a 1 ft 12 awg with another MC4 connector. This in turn connects to my 22 feet of 10 awg. For calculating voltage losses you double the number of feet. The current has to pass through both the plus and minus wires. Air temperature was between 69 and 72 degrees and as solar days go during the test it was mostly good to excellent with about 15 minutes of fair thrown in.

The battery was discharged by runing the refer on DC for three hours, this gave about a 50% SOC on the battery, or 12.26VDC measured. I don't have a hydrometer so can't measure specific gravity to get the real SOC.

1 panel 12.89VDC 4.78amps 2 panels 14.05VDC 9.6amps
Vdrop to controller 0.05 VDC 0.79VDC
Batt voltage 12.75VDC 13.05VDC

Remember when you start to charge the panels want to push as much current as the battery can take. This means the voltage won't start at 14.4VDC. As the battery takes on charge the voltage will rise until the controller can switch to absorption mode, 14.4 VDC for mine.

I started the test at noon and the controller was in float mode by about 3:30 pm.

Float voltage was 13.71VDC at 1.3amps

Absorption Voltage was 14.36VDC at 6 amps.

The system total volt drop is greater than the desired 3% or less and although it can be lived with on bright sunny days it will be a killer on cloudy days or in partial shade.

My best guess is to get rid of the MC4 connectors and run 10AWG from the panel terminals all the way to the controller.

My calculated volt drop was 0.5VDC or about 2.7%

Some further testing before we leave in March this year is required.


Went back and relooked at the figures, the panels were only generating about 135 watts on average. Loss from the panels to the controller was 6.6 watts and total watts lost was 9.6watts. So all considered maybe not so bad. The battery did get a full charge.

[scrubjaysnest]

Additional notes on the solar panels. I test them under adverse conditions while at Stephen Foster SP. I arrived with fully charged batteries. I left the converter turned off and for two and half days the panels never saw sun.
During the brightest overcast the two panels produced together 1/2 amp at 13.09 volts. This was just enough to keep up with our usage. Lights, Tetford, Water pump. With half a day of sun yesterday they produced 18.7 volts at 1.74 amps which is all the batteries would take. This morning I checked and the batteries were at 12.89 volts after sitting all night. The panels worked far better then I expected under the conditions. Need to find my Hydrometer so I have a little better idea of the SOC.

[Wavery]

Originally Posted by Wavery

If anyone is thinking of solar panels, this is a GREAT deal:
http://cgi.ebay.com/80-Watt-solar-pa...item335aaf4bcb

I purchased 2, of these same panels from this seller (@ $240 each) and I can't say enough about them. At @ $209 (incl S&H) they are a steal.

1, 80W panel may be adequate for some, especially if it is not permanently mounted and you are willing to "Chase the Sun" with it. I permanently mounted 2 of these and have had quite impressive results and I'm NOT a power mizer....

This guy's prices fluctuate, depending on his inventory. If you are thinking solar, I'd grab them at this price.

What a different time this is in the "Solar world".

I just came across this post from 2010. I was thrilled about 80W solar panels @ $209 each ($2.61 per watt). Yesterday, I bought 2 NEW, 320W solar panels for $100 each ($0.32 per watt).

At 66"x 40", they probably wouldn't be a TrailManor match but it just shows how much solar has gone down over the past 13-years.

[Bill]

You are so right! Back in 2002, when my first TM was new, I paid $600 each for a pair of 80-watt Kyocera panels, and I had to drive to Flagstaff (300 miles round trip) to get them. I was more than happy to do so. Two or three years ago, I sold them to a non-RVer for $100 for the pair, and considered myself lucky to get that.

Bill