Why does not my 100W Solar Panel fail to charge my two small 12 40Ah solar batteries?

[Did67]

I did not think about it.

Well, the ground is hot over there, but of course, at depth, thermal inertia "clips" the peaks at more than 40 °!

[Christophe]

Bin it is a council for the "following" then!

Make a mini battery cellar so

I think the ideal temperature for lead batteries is 19 ° C ...

[chatelot16]

Hello SEIRMIC;
first of all, I'm sorry for all the expenses you made, you bought 4 regulators?
I advise you not to buy the 150 W panel before solving the current problems, and before buying it, count the number of its photovoltaic cells. If there are more than 36, drop it.
in my opinion, and after all the tests (thanks for the photos) that you did, your concern comes from the batteries. According to the photos, these are AGMs that are not intended for your application. Also avoid car starter batteries and see if you can't find slow discharge batteries (traction type even in 6V that you will put in series). In your area, you should have 250 Wh solar produced per day, see http://www.cipcsp.com/generateurs/generateur-solaire.html, I hope your problems are solved. Regards and good luck.

no the main problem is not the battery since by charging it otherwise it gives a correct use time

the first problem is that the photo voltaic panel is too weak ... it should be allowed to charge the battery for several days in a row without consuming anything at all to hope to charge the battery fully ... and then consume electricity so quite limited ... do not turn on the television until you empty everything

the first thing to do is to measure the current supplied by the panel, to see if the panel works correctly ... an electronic display of the current costs a ridiculous price and should be integrated into any solar charge regulator! a solar regulator without amperemeter is like a suitcase without a handle!

an amperometer allows to see not only a defect of the panel but especially a defect due to a shadow! the slightest obstacle between the sun and the panel which only shadows a single cell is sufficient to reduce the current as if the entire panel were in the shade, because it is the least lit cell of the panel which limit the current of the whole

to mount on the boat or the panels are necessarily mounted with risk of shade there are panels with a freewheeling diode in each cell: it tolerates shadows better ... but the large photo voltaic panels have only one diode approximately every 12v and not one diode every cell

[izentrop]

The panels also suffer under high temperatures. poorly ventilated, it can go up a lot

[Did67]

Yes, but difficult to change something when water is scarce (we are not going to install a sprinkler!). And it has to be in the sun, we can't bury it either ...

Note that the graph is not with an ordinate at zero: it visually exaggerates the loss of yield, which between 20 and 60% is "only" about 25% ...

[Christophe]

The panels also suffer under high temperatures. poorly ventilated, it can go up a lot

It seemed to me (at the top) that it only started to drop around 40 ° C ...

[chatelot16]

there is no limit temperature ... there is a variation of linear output with the temperature, but not catastrophic ... the problem of this subject is not a history of temperature ... it's just a panel too small ... and I do not understand why it spends money to buy cable or battery regulator!

there is only the panel which produces energy ... if the panel is too small there is no solution!

cable section: it is only the cable between regulator and battery which is important: if this cable is too long the regulator slows down the charge before the battery is full: the cable between panel and regulator is much less important: the panel can do a few more volts without significant drop in current

[SEIRMIC]

My dear friends
The sign is not good because I just left with my mother. She uses a 50w panel, all day long, the television works well. A 22 inch TV. With the sun from morning to evening. Except that at night. The battery is discharged and it's just the lights working.
So in conclusion my 100w panel is not even worth 30w. It is a false fabrication. Pity. Thank you all

[izentrop]

The panels also suffer under high temperatures. poorly ventilated, it can go up a lot

It seemed to me (at the top) that it only started to drop around 40 ° C ...

No, it is linear and not very important as the curve shows.
It was to react to the loss of performance of the batteries with the heat ... not that what !!

Seirmic, the measurement of the short-circuit current would have informed of the fault for a long time.

[chatelot16]

it is not the comparison with neighbors that will allow you to understand ... start by measuring the current supplied by the panel!

what is the point of making discussion pages, and not yet having measured the current?

what good is it to show us a photo of the regulators ... we should rather have a photo of the panel on its place of installation!

I'm talking about the risk of partial shade, and you don't answer about it