How much power does solar panels actually generate?

Hi,

Again I'll regret replying, I suspect.

Harold, no one in their right mind on a brand new install would mix different format panels such as mono and amorphous. Of course it can be done. That doesn't make it a good idea, and recommending it is ill advised.

I'd love to expand my system even though it more than meets my needs. I would certain add another controller if I did so.

harold1946 wrote:

pianotuna wrote:
Hi harold,

mono, poly and amorphous eh? Are you daft?

Still waiting on your explination on why it can not be done as long as they are all 12 volt.
I have seen several applications using both amorphous and monocrystaline, both supplying power to the same controller.
I believe the "daft" one, or ignorant one is you.

Ignorant adjective; unaware, uninformed

I suggest you start a new thread with your battery questions.
There are almost as many battery brands as there are solar panels brands, and a choise of at least four types.

Acei wrote:
I'm pretty sure that I will get four 240w Sanyo/Panasonic HIT panels... which batteries, type and how many.

Wow.. that's some setup! You're going to drop a few C notes on a controller for that too!

Get AGM batteries, at least 4, and forget the Trojans. Watering and maintenance get real old after a few years.

At this point, I'm pretty sure that I will get four 240w Sanyo/Panasonic HIT panels, if the trailer can handle it (and from the looks of it, it can). The question is, which batteries, type and how many. From what I gather, Trojan seems to be recommended most frequently.

I'm an engineer but not in this field, so I'm no where near as knowledgeable as you guys here, but I do like planning ahead, come up with close to optimal solution (but not spending ridiculous amount of money). And I do enjoy the feeling that it has been implemented well and am using it even if it only returns negligible improvements.

May be that's an engineer thing. :)

"Roads Less Traveled" - thanks for the info and the links - I'll check them out!

Roads Less Traveled wrote:
, our 490 watts of solar panels..from 24 amps

So your max output is 24a?

In a perfect world it is optimum to have all the sametype and rated panels on any installation. In reality, even if you have a mix and match of panels you will increase your output current everytime you add one. People who have existing systems and are either given or find panels at crazy deals will always see a benefit by adding another panel. Yes, certain types of panels will carry more of the load under lighter load conditions but at some point once the line voltage is dragged down to the lowest common denominator there will be a benefit in adding a mismatched panel as opposed to not adding at all. There are some well educated engineer types on this board who are used to working towards the optimum solution. Nothing wrong with that and I commend them for bringing their knowledge to the table. However, many of us are OK with less than the optimum solution and mix and match systems built over the years, although a compromise, generally are fine. eg if someone gives you a poly panel and you have a mono system, whatever, throw it up there, it'll give you more than you had before. Both of our motorhome systems are like that. We have a little over 800 on the big-un and around 320 on the little-un.

In our experience, our 490 watts of solar panels on our fifth wheel produce 100-160 amp-hours per day, depending on how depleted the batteries are in the morning, how much we consume as the batteries are charging during the day, and how sunny it is.

We did tests on our sailboat (which has 555 watts of panels) where shading is a big issue, and we found out that having the panels shaded was a lot more detrimental than having them pointing away from the sun while the boat was heeling.

As shade from clouds move across the panels, we often see the charging rate drop to about two-thirds -- say from 24 amps to 16 -- and then it rises again as the sky clears.

In general, more is better. If I were to outfit a new RV today, I would put at least 750 watts on the roof. There's plenty of room on our roof to do that.

Panels are half what they cost when we outfitted ours 5 years ago. Plus our lifestyles have changed and we now run two laptops for many hours each day, whereas when we first outfitted our trailer we used only one for just a few hours a day.

We reported our various shading tests on these two pages:

Solar panel installation on a fifth wheel

Solar panel installation on a sailboat

pianotuna wrote:
Hi harold,

mono, poly and amorphous eh? Are you daft?

Still waiting on your explination on why it can not be done as long as they are all 12 volt.
I have seen several applications using both amorphous and monocrystaline, both supplying power to the same controller.
I believe the "daft" one, or ignorant one is you.

Ignorant adjective; unaware, uninformed

i have 505 watts of thin film unisolar panels on the roof
todays harvest was 2075.4 watt hrs, 151.72 amp hs
294.?? peak watts 21.02 peak amps

we have round 900+ amphrs of battery power and a residential 120v fridge
and yes i still run the generator some every day
we full time, getting batteries back to full is a necessity,as we dry camp, no shore power home port for reharging

14.8 x 3 = 44.4 so it could be a bit short charging PWM into a 36. 42 no way, maybe just 24 or 30.
The nominal rating does not really apply so much in this upper zone.

Probably better to say 17 x 3 = 51 required for 36v PWM charging.