What can we really expect with solar?

[Lance]

D8 and the good Dr. Basil Phurrggenschmeerre from Choft and CF did some extensive work with regards to Lunar Panels.
It was some time ago and I'm not sure if they ever reached a conclusive conclusion.


.....but I think we digress..............

[shonky]

Hi, all.

Had a neighbour complaining about the lack of amps coming in from the moon - told him to hold his panel a bit closer to it.

[Dot]

Hi, all.

Had a neighbour complaining about the lack of amps coming in from the moon - told him to hold his panel a bit closer to it.

[Jon and Kay]

I find a 'fair' indication of what to expect from panels being three quarters of the total wattage divided by charging amps
In my case that is 1100w * .75 / 13.2 = 62.5A

Amp Hours depend upon season , cloud cover, air temperature etc.

[grizzzman]

The best I have seen is 82 percent . Many of the solar forums suggest 77 percent when sizing a system.

[T1 Terry]

The best I have seen is 82 percent . Many of the solar forums suggest 77 percent when sizing a system.

Hi Miles, see I know your name now so if I used it a few hundred times I might remember it The general rule of thumb for lead acid charging of any type is 70% of the advertised solar capacity, scattered cloud and cloud edge effect can produce in excess of 100% but only for short periods. Located close to snow or a large body of water will improve the output to between 80% and 90% with the right cloud conditions.
The claim that MPPT will harvest more than a PWM controller of equal quality using panel with a similar Vmp voltage to the battery voltage is just a sales pitch as it requires rare conditions not really seen in Aust to achieve that improvement.
With lithium batteries and the solid state relay control method the rate can be better than 80%, I don't have a technical based answer for this except it's probably due to a combination of direct cable run to the battery reducing wiring losses, voltage sensing completely remote from the solar charging voltage so no additional voltage influence on the target voltage and the fact lithium batteries will maintain a lower voltage while charging than lead acid batteries resulting in a better voltage differential between the solar panel output voltage and the battery terminal voltage allowing the solar panel to dump more of the produced current rather than it being trapped in the solar panel.
No doubt that last part will be a contentious issue with the MPPT camp but in way or an explanation, the genuine Vmp voltage reduces significantly as the panel internals heat up resulting in a Vmp voltage sometimes being lower than the 14.4v or even 14.8v required for some lead acid batteries to fast charge, where anything above 13.6v will fast charge a lithium battery up to well above the 90% SOC mark.

T1 Terry

[grizzzman]

The best I have seen is 82 percent . Many of the solar forums suggest 77 percent when sizing a system.

Hi Miles, see I know your name now so if I used it a few hundred times I might remember it The general rule of thumb for lead acid charging of any type is 70% of the advertised solar capacity, scattered cloud and cloud edge effect can produce in excess of 100% but only for short periods. Located close to snow or a large body of water will improve the output to between 80% and 90% with the right cloud conditions.
The claim that MPPT will harvest more than a PWM controller of equal quality using panel with a similar Vmp voltage to the battery voltage is just a sales pitch as it requires rare conditions not really seen in Aust to achieve that improvement.
With lithium batteries and the solid state relay control method the rate can be better than 80%, I don't have a technical based answer for this except it's probably due to a combination of direct cable run to the battery reducing wiring losses, voltage sensing completely remote from the solar charging voltage so no additional voltage influence on the target voltage and the fact lithium batteries will maintain a lower voltage while charging than lead acid batteries resulting in a better voltage differential between the solar panel output voltage and the battery terminal voltage allowing the solar panel to dump more of the produced current rather than it being trapped in the solar panel.
No doubt that last part will be a contentious issue with the MPPT camp but in way or an explanation, the genuine Vmp voltage reduces significantly as the panel internals heat up resulting in a Vmp voltage sometimes being lower than the 14.4v or even 14.8v required for some lead acid batteries to fast charge, where anything above 13.6v will fast charge a lithium battery up to well above the 90% SOC mark.

T1 Terry

Hi ya Terry
I'm glad to see I'm not the only one that has memory issues with names Cloud edge effect is a kewl thing to see in person. The last M/H I set up 200 watts during the install I had my snapon low amps probe and graphing meter watching current. It was a bright day with fast moving cloud patches. The meter was set to a max of 20 amps. For about 5 seconds it pegged the 20 amp setting. I couldn't believe it would go that high. But in all fairness other then equipment that can take spikes , that much power for such short time is kinda meaningless
The reason I went with PWM over MPPT is the same reason you have described.
I agree that lithium with its low internal resistance along with a shorter route to the battery would undoubtedly help efficiency.
The system I use counts AH I have it set to add 12 percent over what was used the previous cycle at 14.8 and once absorption is done I give a "finish absorption " of 15.3 (a mini equalize if you will)
Have you tracked the losses (due to heat) with using SSRs?
Thanks Terry

[Toolman]

How is this from 9 x 250watt panels = 2250 watts total
38 degrees C outdoor temp and some cloud, lasted a few minutes
PWM controller with extra cooling fan, and double sized cable everywhere

[T1 Terry]

Says photo not found so you'll have to tell us what the readings were.

Just finished fitting 10 x 60w rigid panels with a Dingo driving a solid state relay. These are the same panels as Julian said were no good in poor light at Taggerty. 600w, cloudy but not raining, 26.5 amps @ 14.6v into 300Ah of AGM batteries. Roughly 64% efficient, gotta wait till a full sun day to see the real capability with the original 2 x 80w polycrystalline supplied and fitted by Avida joined in and 6 B&S cabling from the roof to the solid state relay in place of the 7 mtr run of 6mm auto cable fitted by Avida for the original 160w of solar.

T1 Terry

[Toolman]

not sure why the photo not showing, will try again