Roof rack options

[Woodrick]

Has anyone seen this project? 1.2kW of easy deployable PV but needs a 4*4 roof rack.

https://gosun.co/pages/ev-solar-charger

If you look at the details, it's a lot less than is helpful. Just using the number you quoted, 1.2kW is less than 2 mph charging. And that's with the cells pointed at the sun, no clouds, for the entire day.

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[4Dolio]

If you look at the details, it's a lot less than is helpful. Just using the number you quoted, 1.2kW is less than 2 mph charging. And that's with the cells pointed at the sun, no clouds, for the entire day.

Absolutely... I'm thinking of it more as the equivalent to an emergency Jerry can... Maximum 8 hour day might get 16 miles, very likely much less.

But 10 days of camping could yield 160miles...

The main point being, no matter how long you park your ICE car in the woods, it will never gain range no matter what kind of kit you buy or build for it. (Short of a biodiesel setup, and you still need the feedstock).

I can say "I make 80 miles per day of fuel from my homes roof, plus power the house". But it's not as tangible as an array on the roof I can fold out at car shows...

 

[4Dolio]

We are working on a similar solution for our modular rack/cap/rtt. But you can achieve the same with large portable battery and some solar panels from Amazon for less. I don’t think the cost of product ever pays for itself or costs less than supercharging. I think this has been discussed many times.

I look forward to what you come up with... As you and others have said. Such solutions are very obviously not "practical" for normal drivers.

The only valid exception being the Aptera, because it uses a fraction of the energy per distance, at 3x less than a Tesla sedan or 5x less than my CyberTruck or an f-150 Lightning does. It only needs 100Wh/Mile, so each watt is 3~5 times more effective.

My main purpose is as a demonstration for the car shows I attend and for those random chance encounters. "Practically" it's simply a "worst case" or "last resort" onboard power source. I already share that my homes roof PV system makes 80 miles per day and powers my home, but that isn't as tangible as a car show or random impromptu parking lot car show.

Juxtaposition an ICE car which has no such probable capabilities... ICE could possibly have a distillery, or like my brother who did home brew biodiesel for a few years, or even hydrogen and other synthetic short chain hydrocarbons like methane... But those are many orders of magnitude more complex, and in order to be equally renewable need to also use solar PV or wind energy to power the process...

 

[Woodrick]

Absolutely... I'm thinking of it more as the equivalent to an emergency Jerry can... Maximum 8 hour day might get 16 miles, very likely much less.

But 10 days of camping could yield 160miles...

The main point being, no matter how long you park your ICE car in the woods, it will never gain range no matter what kind of kit you buy or build for it. (Short of a biodiesel setup, and you still need the feedstock).

I can say "I make 80 miles per day of fuel from my homes roof, plus power the house". But it's not as tangible as an array on the roof I can fold out at car shows...

There's a lot more that you are missing. The truck uses power when it is charging. The inverter has to be running full tilt constantly. And you don't get 8 hours of solar power in a day.
It's a real expensive solution that you will never use.
That's why you don't see solar cells on EVs, there just isn't enough power generated to make a difference.

 

[4Dolio]

There's a lot more that you are missing.

Yes, I am well aware of all those nuances. I thought I was clear that this is obviously not a practical solution.

You are correct, it would actually likely barely cover the sentry mode and very likely not the cabin overheat protection. It would need to be deployed daily to have a chance, as it's only 200watts when not deployed. I didn't read how large the kWh capacity of its internal buffer battery is, so might be full and then completely wasting energy within hours or days if it's not plugged into a load like the car.

Yesterday my homes PV made power for about 12 hours. Granted the first 2 and last 2 hours are ramping sharply. And even the remaining 8 hours are a large dombes curve. But the one of th generally accepted peak hours used for PV is 8 hours of "good" power per day. Of course it's all dependent on a very many factors. I made 68kWh from 12kW array, so 6 hours were it exactly 12kW, but it wasn't, it was 12 hours. From 9am-5pm it made 59.2kWh, starting at 4kw ending at 5kW, so aboit 50% of nameplate. A 10am-4:30pm span begins & ends at 50%, and made 51.2kWh... This is all just normal basic PV output curves that anyone could look up to learn more about. And your not wrong, I'm that there isn't precisely 8 hours of solar power. It's 8 hours ± 4-ish ours, latitude depend my, weather dependent, temp dependent, PV make/model dependent... Etc etc..

The price, I didn't compare it to a comparable 1200watt PV and small portable battery + an EVSE solution... The value add here is the packaging. Which it the only reason I mentioned it here in a thread about truck roof racks. But now we are all getting into the weeds on the practicality of PV onboard a "normal" car/truck...

 

[4Dolio]

Yes, I am well aware of all those nuances.

My OP was simply 1.2kW of well packaged roof rack required PV array. I do appreciate your input. But I'm mostly just asking about mounting opinions. Specifically I'll have the rail #2+#3 and spare tire bridge installed on my truck. So such a PV array (this or something equally not practical) installed at bar #1+#2 with the tailing edge propped up so to match the height of a 12" wide (tall when mounted) OEM spare tire.

 

[Woodrick]

Yes, I am well aware of all those nuances. I thought I was clear that this is obviously not a practical solution.

You are correct, it would actually likely barely cover the sentry mode and very likely not the cabin overheat protection. It would need to be deployed daily to have a chance, as it's only 200watts when not deployed. I didn't read how large the kWh capacity of its internal buffer battery is, so might be full and then completely wasting energy within hours or days if it's not plugged into a load like the car.

Yesterday my homes PV made power for about 12 hours. Granted the first 2 and last 2 hours are ramping sharply. And even the remaining 8 hours are a large dombes curve. But the one of th generally accepted peak hours used for PV is 8 hours of "good" power per day. Of course it's all dependent on a very many factors. I made 68kWh from 12kW array, so 6 hours were it exactly 12kW, but it wasn't, it was 12 hours. From 9am-5pm it made 59.2kWh, starting at 4kw ending at 5kW, so aboit 50% of nameplate. A 10am-4:30pm span begins & ends at 50%, and made 51.2kWh... This is all just normal basic PV output curves that anyone could look up to learn more about. And your not wrong, I'm that there isn't precisely 8 hours of solar power. It's 8 hours ± 4-ish ours, latitude depend my, weather dependent, temp dependent, PV make/model dependent... Etc etc..

The price, I didn't compare it to a comparable 1200watt PV and small portable battery + an EVSE solution... The value add here is the packaging. Which it the only reason I mentioned it here in a thread about truck roof racks. But now we are all getting into the weeds on the practicality of PV onboard a "normal" car/truck...

A part that you are missing is that unlike your augmentation array, when charging the truck, just must completely power the inverter all the time that it is charging. If solar isn't delivering 100%+ to the inverter, the inverter really has no choice to turn off because the input voltage has dropped to low.
But once it is off, the inverter has enough voltage and can turn on, a vicious loop. The battery can help, but you end up draining the battery to 0 at the end of the day and it may never get a chance to charge back up the next day, because the solar power is going to the vehicle.

If you had a battery array of 50 kWh, or preferable, 150 kWh, you could get past the cycling inverter problem. But 1.2 kWh just means that you have to continuously watch and manually intervene.

This keeps being brought up periodically and most folks don't know enough to realize that it is actually on the other end of the spectrum from a great idea.

 

[4Dolio]

A part that you are missing ...
... continuously watch and manually intervene.

I didn't miss that, all those points are automatically handled by this system. This product has a buffer battery built into it, IDK the capacity, but I presume the inventor has chosen something reasonable.

EVerything I have read about this system leads me to believe they aren't some uninformed hacker, they have numerous other niche solar cooking and power products. You might find something interesting if you at least looked at its specifications? You seem to have not done this yet.

Since EVSE L1 spec has a 6a or 8a minimum (I don't recall precious without looking it up again)... So it can't (if following the spec) offer power if it can't deliver >~600watts.

I would imagine that it has a sort of reverse PPT sort of feature, where as it buffers to its battery until it can produce ~1200 watts for some minimum duration, then it would turn off the EVSE inverter and go to internal charge mode.

I thought it was obvious that there will be conversion losses at the DC rectifier stage to charge itself, and then also at the inverter stage. Plus normal car onboard charger rectifier losses... I didn't intend for this thread to be a white paper on the nuances of solar PV. But it's still been interesting to discuss with you, even though not roof rack related. Hope the rest of the thread doesn't mind the tangent.

 

[4Dolio]

It just occured to me... This PV system has 200 watts always on as part of the case, plus 100watts each from each fold out segment. I think it has 4x and 5x front/rear or visa versa of fold out. And since this would be on my truck, where the rear view is already blocked by the tonneau cover...

Back to the topic of roof rack options:

It might be possible to keep the rear set of folding PV panel segments deployed and secured via the #3+#4 rack bars & perhaps down to the bottom of the tail gate. So perhaps 200w+(5*100w) of semi-permanently deployed PV at all times. ?

I have no doubt it would add some additional laughter and confusion of people asking about how much (or little) energy such a setup would yield. I consider that an advantage to advocate for BEVs and for PV, and also point out how impractical an on vehicle PV array actually is.

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