[gdpetti]

-On the Mega fuse at the alternator... is 150 amp enough? Should it be 200 amp?
-On the CB from positive busbar to inverter, should the CB be rated for the 100 amp like the battery's BMS? or for the busbar which could have up to 150 amps coming in at one time? Or just match the busbar which should match expected input charges of the same near 150amps?
-If the wiring sizes look ok, it comes down to proper sizing of these CBs/fuses... I perfer the CBs as they can act as on/off switches simultaneously.
-Should the CB on the shore power line coming in be 30 amp or 50 amp, given the wire is rated for 30? Even if the outlet is only for the regular 15/20 amp service.
-On solar panel setup, if in series, the amps will remain around 10, but if ran in parallel, the volts would stay around 40amps while the amps would increase to around 30, which would stay in the safe zone all around with this SCC, but then necessitate a combiner box, and then an input gland, right? Are these 3 to 1 types ok for this? First join them on the roof and then use a regular cable entry gland? Amazon.com: JHBOX Solar Panel T Branch Connectors Cable Coupler Combiner - 1 Male to 3 Female(M/3F) and 1 Female to 3 Male(F/3M) (1pair): Garden & Outdoor

 

[GaryBIS]

Hi,
Not to beat this fuse in the line from the PV panels to death, but a couple more thoughts...

For people do put a breaker or fuse in the line from the PV panel to the charge controller, they usually put the fuse inside the van near the charge controller (in thier electronics bay). This placement does not do any good for a short to ground anywhere along the wire. The fuse would have to be placed on the roof up near the PV panels to protect for a short to ground -- ie the fuse has to be as close as possible to the current source (the PV panels). So, not so convenient to get to when you want to shut the solar system down.


If you short the output of a PV panel, it produces what the manufacturers call short circuit current (Isc in the specs) and this current is generally not much greater than the panel produces when operating at its max power point (Impp) -- so PV panels are not like batteries that normally produce modest currents to devices they are serving, but if shorted to ground can produce huge currents that can melt wires and cause fires. When the PV panel is shorted to ground (say by a short to ground in its supply wire) it only feeds a bit more than its nominal current through the wire.

The PV panel short circuit current is so close to its nominal current that it would be hard to pick a fuse that would blow on a short, but not blow under normal operation -- especially when you consider that the PV panel is going to make more current in colder temps and higher elevations.

As far as having a way to shut the solar system down easily, I just use the breaker that is between the house battery and the charge controller.

But, if you feel better to put a fuse in the PV line, it does no harm (that I can think of).

RV8R: If the weather is right, I plan to do the Vortex Generator MPG test on Thursday. Assuming the test method I've come up with actually works and produces a good estimate of the MPG change, then I plan to repeat the test for the solar panel off and on and maybe some other things, but this will be later in the summer.


Gary

 

[HarryN]

Thanks Gary

I do not have solar on my van roof yet (Still Pondering It). I understand the Pros & the Cons I have thought of are;

1) Aero Drag (change in MPG)
2) Added heat to my roof (why I choose white in the first place)
3) Serviceability of the roof (access for cleaning & repairing future roof leaks)
4) Securing the panels onto the roof (& the ability to remove for item #3 above)

I am in no rush & have the luxury of time right now to think/research. Im am also currently experimenting “real world” with solar @ my cabin “self educating & reading from different sources“.

I hope to see your datapoints on the MPG testing you're planning.

On my Dodge 2000 mini van I did a very quick and dirty installation.

2 each 150 watt panels bolted down directly to the factory roof rail. Mounted cross wise - no added parts other than a few washers and bolts.

I say it was quick, but there were a couple of nuts that were a real pain to get on the bolt due to clearance.

This van has essentially zero insulation and serves as my test bed. I can sit in the drivers seat, reach up and feel the roof interior both where the front solar panel is and is not. I know that you would prefer real data, but there is no question that the steel under the panel is cooler and the solar panel is acting like a sun shade. (edited for more clarity)

So far I have done nothing to make the air flow better, so the front panel is literally a flat bulldozer blade going through the air. On that particular van, this reduced my mileage by 2 mpg. I keep pretty close tabs of my fuel efficiency so I am comfortable with that number. For me I don't really do that much driving so it was acceptable but I should work on that.

 

[RV8R]

On my Dodge 2000 mini van I did a very quick and dirty installation.

2 each 150 watt panels bolted down directly to the factory roof rail. Mounted cross wise - no added parts other than a few washers and bolts.

I say it was quick, but there were a couple of nuts that were a real pain to get on the bolt due to clearance.

This van has essentially zero insulation and serves as my test bed. I can sit in the drivers seat, reach up and feel the roof interior both where the front solar panel is and is not. I know that you would prefer real data, but there is no question that the steel under the panel is cooler than the shade of the panel.

So far I have done nothing to make the air flow better, so the front panel is literally a flat bulldozer blade going through the air. On that particular van, this reduced my mileage by 2 mpg. I keep pretty close tabs of my fuel efficiency so I am comfortable with that number. For me I don't really do that much driving so it was acceptable but I should work on that.

Thanks HarryN

Regarding heat increase under the panel, I am confused by “under the panel & shade”. Are you saying the roof is cooler under the solar panel than the van roof that is exposed to the sun?

The mileage is a big consideration. 2mpg decrease on a “say 20 mpg vehicle as I am not sure what a minivan gets” would be a 10% loss in fuel economy. If I were to experience a 10% loss on my PM due to solar panels I would probably bail on the idea. In Canada fuel is way more than the USA & a quick calc is fuel costs $0.30/mile. 200,000 miles @ 10% = $ 6,000 additional fuel costs. That has to be weighed against, the fuel needed to drive the PM alternator to charge the batteries & replacing a more used alternator etc vs the cost of buying & maintaining a solar charging system.

I know Gary did a heat experiment under solar panels that I cursory read many months ago, & I think the conclusion was if you had a “white van” the heat retention under the solar panels was significantly higher than the painted van roof. (I need to revisit that thread).

edit; found the info on Gary’s site (I believe his test results are significant higher heat under the solar panels than a “white van roof surface”).

Effect of RV Solar Panels on Heat Gain – Build A Green RV

www.buildagreenrv.com

Where the end the ceiling/insulation

I’ll be installing my vent fan today and after that I want to start finishing up my ceiling insulation and ceiling. My question is where do people stil their ceiling at. Do most people stop till the very end where ceiling meets storage area above front cabin? I feel like I you go all the way to...

www.promasterforum.com

Thanks for your post Harry, as this kind of data (even if a gut sensory feel) helps me make decisions.

 

[GaryBIS]

Hi Harry,
2 MPG is a lot.
What do you have in mind for reducing drag?

Gary

 

[HarryN]

I don't know how to post photos on internet forums, so I am going to point you to an "item" that I created in my web store so that you can see what that mini van solar setup looks like.

WirlNet, Inc

wirlnet-inc.square.site

When I bought that van in 2007, it was getting ~ 18 mpg while driving 68 mph on a particular stretch of I5 in cruise control mode.

I did a few things to clean up the air intake and switched from 10w-40 standard oil to 0w-20 mobile 1 and got it to be 23 - 24 mpg under the same circumstances.

The panels dropped this to 21 - 22 mpg.

This van is 20 years old and has 170K miles on it, so the fuel efficiency is important , but not as important as for someone driving a lot of miles per year.

___
My preliminary ideas for reducing drag are to buy some wood molding that is shaped like a 1/2 round or perhaps elongated and mount it to front of the first panel and to the rear of the 2nd.

Legacy Heritage 2 Inch Half Round Dowel Pattern Column Molding

Legacy Heritage 2 Inch Column Molding Half Round Dowel Pattern can be used as trim molding for cabinets, mantels, windows, and more.

www.vandykes.com

or perhaps more of an 1/2 oval instead of a 1/2 round.

___

I was going to try to eliminate the gap in between the panels (on top) so that the air flow would be less impacted by it. On this van possibly with just some heavy aluminum duct tape closing the gap on top, or perhaps something similar but heavier duty.

__

Just to be clear - the interior roof feels much cooler under the panels on this van. They essentially act as a sun shade.

I did read GaryBIS thread and measurements. In no way do I dispute his measurements, I honestly don't know how to explain the difference in his readings vs what I can feel on the inside of the van. Possibly a different ambient temperature? Maybe due to the panel mount angle and air flow? The panels have a substantial slope in the middle (front to back) vs flat mounted panels. Not sure.

 

[Baxsie]

I don't know how to post photos on internet forums . . . .

This forum is great for that. Just click the little picture icon:

 

[keeponvaning]

Even easier than that - you can just drag and drop or cut & paste

 

[phil]

anybody can do it, copy image, paste

 

[RV8R]

I don't know how to post photos on internet forums, so I am going to point you to an "item" that I created in my web store so that you can see what that mini van solar setup looks like.

WirlNet, Inc

wirlnet-inc.square.site

When I bought that van in 2007, it was getting ~ 18 mpg while driving 68 mph on a particular stretch of I5 in cruise control mode.

I did a few things to clean up the air intake and switched from 10w-40 standard oil to 0w-20 mobile 1 and got it to be 23 - 24 mpg under the same circumstances.

The panels dropped this to 21 - 22 mpg.

This van is 20 years old and has 170K miles on it, so the fuel efficiency is important , but not as important as for someone driving a lot of miles per year.

___
My preliminary ideas for reducing drag are to buy some wood molding that is shaped like a 1/2 round or perhaps elongated and mount it to front of the first panel and to the rear of the 2nd.

Legacy Heritage 2 Inch Half Round Dowel Pattern Column Molding

Legacy Heritage 2 Inch Column Molding Half Round Dowel Pattern can be used as trim molding for cabinets, mantels, windows, and more.

www.vandykes.com

or perhaps more of an 1/2 oval instead of a 1/2 round.

___

I was going to try to eliminate the gap in between the panels (on top) so that the air flow would be less impacted by it. On this van possibly with just some heavy aluminum duct tape closing the gap on top, or perhaps something similar but heavier duty.

__

Just to be clear - the interior roof feels much cooler under the panels on this van. They essentially act as a sun shade.

I did read GaryBIS thread and measurements. In no way do I dispute his measurements, I honestly don't know how to explain the difference in his readings vs what I can feel on the inside of the van. Possibly a different ambient temperature? Maybe due to the panel mount angle and air flow? The panels have a substantial slope in the middle (front to back) vs flat mounted panels. Not sure.

Hi HarryN

Thanks for clearing that up - Much Appreciated.

As they say a picture is worth 1000 words & seeing the minivan setup, I understand more.

Regarding heat build up vs shade of the white metal roof (your hand temp test vs Gary’s testing); I can visualize your report of a cooler feel as the vehicles & solar panel installations are different.

The more important issue for me is mileage with solar panels. I can also visually see where your minivan setup could have a 2mpg reduction. In my experimental aviation hobby, “form drag” is everything that battles speed (or course a bit different @ 200 miles per hour). The opponent to “form drag” is “horsepower”, I think we all know that. The loose calculation for me is I can overcome form drag with wallet.😳

When I visited BMW Welt in Munich, one of my “take aways” was the wishbone suspension on the F1 racer that was formed in the shape of an airfoil. My gut tells me if you could fabricate a sheetmetal edge similar to a leading edge of a wing that would reduce your drag on the minivan panels more than a 1/2 round.

Regarding PM solar panels; my non-researched gut opinion is keep as low profile to the roof as possible (more expensive flexible solar panels possibly, although the use of these have other problems) & channel the airflow off the van roof & over the panels. I envision a leading edge that shallowly ramps up from the peaked & valley corrugations of the van roof & meets at the top leading edge of the solar panels. The sides of the solar panels to be tightly cowled to the van roof (air tight). Possibly a trailing edge ramp down at the back of the panel similar to the leading edge. This would be a ton of work for theoretically not much gain.

I have done much of my design/build (6 months process part time started the end of 2018), without pondering. I am going to think about & research more the pros & cons of solar on my van before pulling the pin.🤔

My biggest hangup to date is what will it do to the mileage. Which at the end of the day is why we built a DIY PM van vs buy a small Motorhome - Economics & cost benefit & total cost per mile (not time) as our intended use is “travel”.

 

[HarryN]

I am glad that the photo helped.

My original plan was to just put one panel on - right down the middle / front to rear so that it would be less obvious.

Since I had 2 panels sitting around already in the garage already and was needing to do something with them or risk them breaking, it seemed like a good idea to put at least one on the van. My son talked me into putting both of them up there.

The funny thing is that as obvious as those panels are in the photo, most people walking past them don't even notice them. The van isn't all that tall and so many people here have ski racks that it all just kind of blends in. There is a local coffee / donut shop that I go to (too often) and BS with some others (when we aren't in covid lock down). Most of them never noticed the panels until I pointed them out.

The police noticed the panels and used to chalk my tires but I think eventually decided that I didn't live in it. My neighbors are still trying to figure out why I have panels on my van when it isn't an EV.

At one time the paint color was silver / gray, but now it is sort of peeling.

 

[Winston]

Even easier than that - you can just drag and drop or cut & paste

Wow, you mean third party hosting is no longer required?

 

[WanderingWakes]

A few data points on mileage and solar panels on the roof.... 2018 High Roof 2500 159" WB

1100 mile trip home with the empty van (GA to OK) -- 18 mpg
1500 mile trip OK-NM-OK with only a MaxxAir fan on the roof, minimal interior build out -- 17.5 mpg
1700 mile trip OK-CO-OK with MaxxAir, 3 x 100w panels, 9" high roof AC installed -- 17.7 mpg (not all highway, so that helped)

On all of these my philosophy is to drive 65 mph max, in an effort to cut wind drag losses some.

I realize these are not carefully conducted experiments, but I am definitely not seeing a 2 mpg drop, even with a roof AC which is much higher profile than a solar panel.

 

[keeponvaning]

Wow, you mean third party hosting is no longer required?

Yes, it’s no longer required or even advisable.

 

[Baxsie]

Wow, you mean third party hosting is no longer required?

Yes! This forum software (XenForo) is great. I liked it so much we upgraded our old vBulletin forum at work to it.