How much solar charging are you getting while driving?

[HiTech]

Every so often someone makes the point that they get significant solar charging while driving.

For those of you that notice this, any thoughts on how much charging you are getting just from solar (vs. say alternator), and how much solar yield you are getting compared to being stationary?

What panels and controller are you using to see the result?

Jim

[pigman1]

A fairly simple process to tell with our system. We run 560W of panels and a Morningstar MPPT controller with a remote readout. Depending on the length of time we travel, sun conditions, and how much power we are using in the coach we've seen in excess of 400AHr'scoming off the solar system. That is also based on the house batteries being close to completely charged when we start the run. I can reset the controller to read amp-hours, watts or KW and can reset it to zero whenever I want.

[HiTech]

landyacht318 wrote:
My solar contributes to the alternator's amps up until the house batteries reach 14.5.

My solar is programmed to hold 14.5 for 90 minutes, yet my vehicles voltage regulator likes to prematurely drop back to 13.7.

After the vehicles voltage regulator decides 13.7 is plenty, and if the solar has not seen 90 minutes at 14.5, then the solar then contributes again, and several times I have seen the solar actually powering a portion of the vehicles electrical demands.

But in general it makes little difference. I like quenching my depleted house batteries with 60+ alternator amps in the morning, even if short lived. They seem to like it.

This time of year I often don't even bother bringing the alternator into the house battery loop.
I like how quickly my engine starts when 3 batteries are cranking the starter, but I don't want the fridge compressor to be running when I crank the starter with assist from the house batteries. With my manual switch, I feel safer just leaving the 2 banks separate.

Seems like a good partnership, being able to quick charge the house batteries at high amps when low if needed, but letting solar provide 12 v charging and even energy back to the engine when it has the power to do so.

Jim

[HiTech]

handye9 wrote:
I have two of these.

This is the controller I use.

Battery bank is two 12 volt group 24.

When towing, I don't know how a person would tell how much power was coming from solar and how much was coming from tow vehicle, unless the tow vehicle provided no charging at all.

Length of time a person could expect for boodocking, depends on power usage, hours of sunlight, angle of sunlight, size (and condition) of battery bank, size and type of panels, type of controller, and wire size used to hook it up.

All my interior and exterior lights are LED, and my television is (low watt) 12 volt. No inverter to run any 120 volt appliances. We have boondocked for up to 5 days, with no noticeable drop in battery power. The solar panels kept up with a couple hours (daily) lights and television, and, all the parasitic draws from gas detector, refridgerator, etc.


I also have a panel on my TC. It is a single 135 watt with PWM controller.

Just out of curiosity, one sunny day, I disconnected the battery and connected the cables from the controller, directly to the converter. I was able to watch television and turn on a couple lights (also LED), with nothing but solar power.

That link to the Unisolar 128's seems like a great price. Basically $1 per watt!

Jim yes all those posts from experienced people referencing great charging while under way got me wondering. I'm also corresponding with one of the solar car teams that has won a lot of races to understand a little more about more advanced solar controllers. Our case of moving in an RV and generating solar power on the go has some things in common with what they do.

Jim

[JiminDenver]

Interesting thread Jim.

Considering our portable panel rides on the top of the Expedition, it would be easy to run the lines back to the trailer and charge on a extended drive. I'm still trying to explain to Honey that the air movement is keeping the panel from cooking us in the truck. lol

[landyacht318]

My solar contributes to the alternator's amps up until the house batteries reach 14.5.

My solar is programmed to hold 14.5 for 90 minutes, yet my vehicles voltage regulator likes to prematurely drop back to 13.7.

After the vehicles voltage regulator decides 13.7 is plenty, and if the solar has not seen 90 minutes at 14.5, then the solar then contributes again, and several times I have seen the solar actually powering a portion of the vehicles electrical demands.

But in general it makes little difference. I like quenching my depleted house batteries with 60+ alternator amps in the morning, even if short lived. They seem to like it.

This time of year I often don't even bother bringing the alternator into the house battery loop.
I like how quickly my engine starts when 3 batteries are cranking the starter, but I don't want the fridge compressor to be running when I crank the starter with assist from the house batteries. With my manual switch, I feel safer just leaving the 2 banks separate.

[HiTech]

MrWizard wrote:
i have the blue sky 2000e
one my best days solar was on a drive back to LA from San Diego in july of 2011
'air cooling' from the moving air , on shore breeze no smog no clouds

an the alternator, seems a little low according to my digital at the dash
13.6v
need to check it at the batteries with engine running

Had not really thought of the cooling effect. Depending on how the panels are mounted and which panels, that could be by far the largest impact vs stationary charging.

Jim

[HiTech]

SteveAE wrote:
A lot in my case.
I have never data logged it, but I know for a fact that before I installed solar, my batteries wouldn't fully charge while traveling. After adding the solar, they are always fully charged early in the day. My panels (300 watts) are flat on the roof. Solar charging while traveling is such an under considered reason for adding it.

Steve

Exactly what I am looking into here. There is benefit even for people who camp in shade, depending on how much time is on the road vs dug in.

Jim

[HiTech]

smkettner wrote:
Enough to run my 2-way fridge on electric through an inverter.
So at least 28 amps. OK maybe some comes from the truck but I don't think very much.

I would expect better performance when rolling as the 60 mph breeze will help cool the panels.

Wow! I thought I remembered you getting substantial charge while driving.

On my setup with the Watts Up I will be able to isolate output from the solar controller so it will be pretty easy to see what it contributes.

Jim

[MrWizard]

i have the blue sky 2000e
one my best days solar was on a drive back to LA from San Diego in july of 2011
'air cooling' from the moving air , on shore breeze no smog no clouds

an the alternator, seems a little low according to my digital at the dash
13.6v
need to check it at the batteries with engine running

[SteveAE]

A lot in my case.
I have never data logged it, but I know for a fact that before I installed solar, my batteries wouldn't fully charge while traveling. After adding the solar, they are always fully charged early in the day. My panels (300 watts) are flat on the roof. Solar charging while traveling is such an under considered reason for adding it.

Steve

[time2roll]

Enough to run my 2-way fridge on electric through an inverter.
So at least 28 amps. OK maybe some comes from the truck but I don't think very much.

I would expect better performance when rolling as the 60 mph breeze will help cool the panels.

[harold1946]

HiTech wrote:
Because of shadows from semis, buildings, bridges...etc hitting the PVs, and because of less tree cover. Also because of rapidly changing direction of illumination and most likely little tilt. But especially the very rapidly changing illumination/shadow pattern, and what different controllers might make of it. Many factors. If you look at the solar race cars, they have much more advanced control strategies than most stationary charge controllers.

I imagine PWM would run effectively the same.

But I am curious in what people here actually observe with their set ups.

Jim

This would be another fine study project that would give loads of usless information if one had nothing better to do but watch a solar panel monitor while traveling.
After gathering all this information, what would you do with it that would be benificial?

[handye9]

I have two of these.

This is the controller I use.

Battery bank is two 12 volt group 24.

When towing, I don't know how a person would tell how much power was coming from solar and how much was coming from tow vehicle, unless the tow vehicle provided no charging at all.

Length of time a person could expect for boodocking, depends on power usage, hours of sunlight, angle of sunlight, size (and condition) of battery bank, size and type of panels, type of controller, and wire size used to hook it up.

All my interior and exterior lights are LED, and my television is (low watt) 12 volt. No inverter to run any 120 volt appliances. We have boondocked for up to 5 days, with no noticeable drop in battery power. The solar panels kept up with a couple hours (daily) lights and television, and, all the parasitic draws from gas detector, refridgerator, etc.


I also have a panel on my TC. It is a single 135 watt with PWM controller.

Just out of curiosity, one sunny day, I disconnected the battery and connected the cables from the controller, directly to the converter. I was able to watch television and turn on a couple lights (also LED), with nothing but solar power.

[RJsfishin]

Yeah, kinda an empty question ? It would depend on a lot of different circumstances. And w/ the alternator holding the system at + 14 volts, I wouldn't expect solar to put out much at all anyway.
But my solar doesn't put out much at all while driving, because the panels are in a storage comp 🙂