Xplorer AM Solar Setup

[Saldar]

I know you have lots of experience with solar panels. Is the 20A/400W you hope for the practical reality? I was thinking on an ideal day you could get 5A/hour off 100w, and with 4 ideal hours that would be 20A/100W, so 80A for your 400W...ideal. Are real days typically 4X worse than ideal, or am I calculating wrong?

[GeorgeRa]

Originally Posted by Saldar

I know you have lots of experience with solar panels. Is the 20A/400W you hope for the practical reality? I was thinking on an ideal day you could get 5A/hour off 100w, and with 4 ideal hours that would be 20A/100W, so 80A for your 400W...ideal. Are real days typically 4X worse than ideal, or am I calculating wrong?

Just a correction so numbers have meaning
A - amper - curent
Ah - amphour - 12V battery capacity 1Ah means current of 1A for an hour.

[Saldar]

Thanks for the clarification George! I wondered if Wincrasher could get closer to 80Ah total over a good day rather than 20Ah. But with your help, I now think he hopes to see his four panels together producing 20A instantaneously on a given sunny moment (5A each). And that could add up to 80Ah over 4 sunny hours, which makes sense to me.

[wincrasher]

I suspect I'll get a bit more than that for the day.

Lately I'm getting a total 11 hours of sun.

On the 180watt panel, the system was reporting 770 watt-hours for the day.
Of course those peak hours 11 am- 3pm are the highest output. Less before and after, but those watts add up too. Very rarely did I ever see any output approaching the 180 rating - the most I ever saw was around 169 watts, but most of the time it's 110-125 watts. But the output during charging was pretty good - 8-9 amps usually. So my 5 is basically assuming a little better than 1/2 what I get out of the 180 watt panel (I'm an optimist).

These 100 watt panels have a higher efficiency rating, but I have no real world data yet to report. My controller does data logging, so I'll have some history reports to share going forward.

I have one panel connected today while I await delivery of my new panels, so later I'll have some data to share. Hopefully my palm tree isn't shading it.

[wincrasher]

Originally Posted by Saldar

Thanks for the clarification George! I wondered if Wincrasher could get closer to 80Ah total over a good day rather than 20Ah. But with your help, I now think he hopes to see his four panels together producing 20A instantaneously on a given sunny moment (5A each). And that could add up to 80Ah over 4 sunny hours, which makes sense to me.

Yes, when I said 20A, I meant the instantaneous output. Typical day in SoCal, I'd hope to see 100-120Ah for the array.

[BBQ]

.

There are websites with tables showing you how much solar you can harvest.

Just plug in your latitude, your solar panel angle, the time of the year,
and they will give you the theoretical results.

[booster]

Originally Posted by BBQ

.

There are websites with tables showing you how much solar you can harvest.

Just plug in your latitude, your solar panel angle, the time of the year,
and they will give you the theoretical results.

There was an thread on that topic here a while ago with links to solar calculators that would give you your total ideal harvest any place in the world on any day of the year.

[wincrasher]

Well it looks like we had a good day according to the log.

460 watt hours for the day. 11.41 hours of bulk charging. Peak of 83 watts and 20.6 volts.

As a percentage of the spec, this panel is quite a bit more efficient than the 180 watt panel. I think that part of the day it was shaded by my palm tree.

Didn't matter though, battery was at 98% at dusk. I had the maxxair fan and the refrigerator running all day. Actually they were running all night too.

From a calculator I found, it says SoCal should be 4.08 hours of peak sun and output should be .41 kW. Looks like it's doing pretty good then.

[BBQ]

Originally Posted by wincrasher

Well it looks like we had a good day according to the log.

460 watt hours for the day. 11.41 hours of bulk charging. Peak of 83 watts and 20.6 volts.

As a percentage of the spec, this panel is quite a bit more efficient than the 180 watt panel. I think that part of the day it was shaded by my palm tree.

Didn't matter though, battery was at 98% at dusk. I had the maxxair fan and the refrigerator running all day. Actually they were running all night too.

From a calculator I found, it says SoCal should be 4.08 hours of peak sun and output should be .41 kW. Looks like it's doing pretty good then.

[booster]

I think that panel is the Grape Solar 100 watt that is about 20" X 40" ? If so, it is the same panels we have.

You are getting good output from it, for certain, looks like you got a very good one. The two we got first do a bit better than the one we got later, but well within the rated output range from Grape Solar. Wish they were all as good as the first two, though.

The solar calculators can get pretty wonky in how they do stuff, I found when I was messing with them. A lot of them will only count the "peak sun" time in the runup, and not the entire day. I couldn't find any that would do the integration needed to cover the entire daylight hours to get a better total.

I did put together a spreadsheet that will do a pretty good approximation of a real integration that works pretty well. It is discussed in this thread from a while ago. It just requires one row to be filled in from the solar angle calculator link that is given. You may want to try it to see how it compares to the calculator you found and used.

http://www.classbforum.com/forums/f2...ions-6543.html

[booster]

Here is what I got for yesterday for San Diego using the calculator mentioned above. At 460 watt-hrs, you are quite good.

[wincrasher]

Not sure where the source their panels. I’ll see if there is any info in the shipment due to me today. The are 41 x 21. The calculators I found online are pretty rudimentary - i’d Like to play with the one Booster referenced above.

[booster]

If the panels are from AMsolar, the 100 watt panels from Grape have in the past carried a GS100 part number for Grape Solar 100 watt. Ours had a sticker on the backside along with some performance data.

[GeorgeRa]

The efficient 100W Grape Solar are backcontact ones, a way to recognize them is by their lack of connecting traces on the top. 21” x 41” are the backcontact ones which I also have.

[wincrasher]

The 160 watt panels I put on the bus were Grape panels. So far I've been very happy with them. Reasonable price, high performance.

[wincrasher]

Another good day - 470wh. My other panels came in and I put them together, but ran out of light, so mount them tomorrow.

Attached is the sticker on the back. No indication that it's a Grape panel.

[booster]

That is pretty certainly a different panel than we have, as the size is a bit different. Ours are just under 21" and 41" and carry a GS100 number. They look to be very efficient from your numbers.

[wincrasher]

Well, I got my solar project sorted today. I added 3 additional 100watt panels for a total of 400 watts. I ended up having to peel up the combiner box, clean all the dicor off it and the roof and re-orient it under the middle panel (I didn't want to drill yet another hole and move the box entirely). I secured it with VHB tape. There was only one place it could go so everything would fit. One of the panels is pretty close to my MaxxAir fan, but it can't be helped. It can cast a shadow, so that will be something to be conscious of when deciding on how to park. At high noon, the array was putting out 22.5 amps at 13.5 volts (on the batteries). Not a bad result and thankfully, it all worked perfectly on the first attempt! Next I'll secure my wiring to the front panel, and Dicor all the feet and the combiner box.

[BBQ]

.

With 4 panels,
you could connect 2 sets of 2-in-series. This would raise the voltage and increase the efficiency.

Just a thought.

[GeorgeRa]

Nice set-up, congratulation. I second BBQ recommendation. What are the black knobs for?