Remember zapping ants with a magnifying glass?

Hi 12th,

Thanks for the correction.

pianotuna wrote:
Watts per square meter from sunlight are about 1004 watts. 527 watts are infrared, and 32 watts are ultraviolet.

That leaves 445 for visible light. Given a 17% efficient solar panel harvesting 75 watts is about the best that can be done cheaply. That represents about 4.5 amps.

Not quite sure of your calculation there, but panel efficiency is calculated using the total irradiance from the sun, approx. 1kW/m^2 even though longer wavelength, lower frequency light has less power (infrared). This means that the average panel produces 140-170 watts per sq. meter of panel.

As far as the concept car, wonder what are they doing with the 8x heat generated?

Hi Roy,

Watts per square meter from sunlight are about 1004 watts. 527 watts are infrared, and 32 watts are ultraviolet.

That leaves 445 for visible light. Given a 17% efficient solar panel harvesting 75 watts is about the best that can be done cheaply. That represents about 4.5 amps.

There are amorphous panels that do harvest more than one frequency of light. Their efficiency is lower overall so their size is even larger. The most famous of these are the Unisolar panels (bankrupt).

There are infrared devices but the efficiency is much lower (for example the millivolt range for gas valves) and the cost is astronomical for an appreciable amount of power. I.E. enough to charge a cell phone.

I think it highly unlikely that they can get 40 amps from the tiny surface area they show in the picture, even using concentrator technology.

RoyB wrote:
Pianotuna - I saw that as well on my battery banks but I would see a 0% to 50% SOC battery wants to use around 15-17AMPS of DC charge for 15-20 minutes or so and then start tapering back as the state of charge gets better.

It appears to me once you get past that first initial high charge point then the solar panels will work for you like gang busters getting to the 85% to 90% charge state in a 3-4 hour time period...

It appears they are wanting to get their panels to give 8 times more output using the magnifying type design panels. That would take the usable 5-6AMPS you see coming from the present day solar panels go to 40-48 DC AMPS if you can believe what they are wanting to get.

Sounds like alot to get to me based on my simple understanding of how the solar panel things works......

Roy Ken

RoyB wrote:
Battery science for me would have to be a source giving 14.4VC with 20AMPS capacity for each battery in the bank.

I'm assuming you're talking about the starter battery in the C-MAX?? Cause the Li-on battery pack is 312V not 12V. None of the LI battery packs are low voltage. You don't want RV type voltage drop (and the excessive heat that goes along with that) with the amount of discharge current these batteries are capable of and you don't want thick, heavy wires either.

scroller95969 wrote:
When is says "off-vehicle solar concentrator" does that mean that it is some kind of lens that you would have to park next to in order to receive a charge?

Yes, or wait a few more days for the same charge. The fresnel lens (think light houses) concentrates the sunlight to 8 times the intensity, thus the "zapping of the ants"

When is says "off-vehicle solar concentrator" does that mean that it is some kind of lens that you would have to park next to in order to receive a charge?

Usable concept and I'm sure we'll see more of roof-top solar for cars. 8KW in four hours is nothing to sneeze at, that PVA is humpin'.

If you had a cloudy day and the car had regenerative braking, all you need is one big downhill run, lol.

Pianotuna - I saw that as well on my battery banks but I would see a 0% to 50% SOC battery wants to use around 15-17AMPS of DC charge for 15-20 minutes or so and then start tapering back as the state of charge gets better.

It appears to me once you get past that first initial high charge point then the solar panels will work for you like gang busters getting to the 85% to 90% charge state in a 3-4 hour time period...

It appears they are wanting to get their panels to give 8 times more output using the magnifying type design panels. That would take the usable 5-6AMPS you see coming from the present day solar panels go to 40-48 DC AMPS if you can believe what they are wanting to get.

Sounds like alot to get to me based on my simple understanding of how the solar panel things works......

Roy Ken

Hi Roy,

Above 85% 12.5 amps is all a battery will accept. Above 95% 5 amps.

From the point of view of battery charging c/20 is a good plan for "weekend warriors" for the solar system will totally recharge the system between trips.

For small banks of about 200 amp-hours, c/8 is a number to aim at. It is also the number to aim at for full time use of the RV, while bumping up bank size. A 400 amp-hour bank would be great with 600 watts of solar.

Battery science for me would have to be a source giving 14.4VC with 20AMPS capacity for each battery in the bank. If I have this then I can successfully charge up my batteries in a four hour period.

Anything less then it takes many more hours to accomplish a charge. I would think the small footprint space on the roof of the small FORD vehicles would be a hugh challenge to over-come even with magnifying solar panel material...

Interesting concept idea however...

Roy Ken