Solar panel setup questions.

[wickydude]

Originally Posted by freebeard

Why no benefit until the last panel was moved?

Because they're setup as one string I think. The one that gets the least light drags down the other ones. Same as when one of the panels is shaded.

[M_a_t_t]

I ordered the batteries, then found out they don't ship batteries to the US. Back to window shopping I guess.

[saturndude]

Q1: I'm considering trying to do a dual setup on the batteries so I can discharge one then switch and use the other while charging the other one. How hard would this be? Is it as easy as switch batteries or am I missing something?

A1: connect them in parallel to combine their capacity, there is no benefit to charging them independently. in fact, I would say its better to buy the two batteries and keep them as a pair, that way they are matched and don't self discharge through the weaker one.



Q2:does the controller in the 2x 100watt kit charge the battery(ies) or do I need a seperate charger?

A2: the controller is the charger. it is actually a "charge controller". a PWM controller is plenty good for use on 12V panels (even though they may put out 17v in full sun) MPPT is best for higher voltage panels.


Q3: I wouldn't leave my starting battery in place and connect to one of the batteries in back, alternator in place. That would be fine correct?

if I were you I would keep the van battery in there and add an isolator commonly used in RVs that connects to the ignition and connects the batteries when the van is running therefor charging them all via the alternator


Q4: I would like to make an aero cap sort of thing for the roof of the van to hopefully decrease the drag I would get from the panels. I was thinking I would attempt building it like changzuki did his body for the centurion. keeping in mind the teardrop shape should I just go for a flat top or make it an angled top? Would it be worth trying to angle the panel(s) (I understand for max power I would have to try and park facing with them facing the sun) and top or not worth the effort?

A4: I think the best way to reduce aero drag from panels is to mount them as close / flush with the roof as possible. they actually have very thin, flexible, self-adhesive ones. sounds like a lot of effort to build a cap for something that may not do anything at all.

Also, you can mount the brackets directly to your roof without drilling holes by using the proper type of adhesive. and in my opinion it is not worth messing with tilting swiveling mounts. by the time your done designing, building, and installing them, you could have just bought another panel.



Q5: Lead acid batteries need venting for while they are charging correct? What type doesn't need venting?

correct, they should be vented. SLA (sealed lead acid) is sealed as well as "gel cells", lithium and NMh. in terms of capacity per $ there is no comparison to a deep cell lead acid batteries, it is worth just adding a vent and using them. in my opinion, Lithium batteries would be a waste in a 5,000lbs vehicle.

Q6: The reviews for the ebay solar panel are all positive, I would rather go with ebay ones because of cost. Has anyone had any problems with ebay solar panels? (maybe not necessarily the ones I linked)

A6: I have bought many eBay solar panels and been happy with all of them!

good luck!

[freebeard]

The last episode of EVTV talks about their new solar panel installation. They say that the people who are making solar roadways claim a horizontal install only loses ~10% depending on the refractive index of the cell.

Twilight is not worth chasing?

[M_a_t_t]

Did they consider the fact of roads on hills facing the sun and such?

I already bought the 2 solar panels from home depot, they're rigid and were on sale so they were actually cheaper.
I also bought 4 20AH lithium (LifePo4) cells.
Going to buy this charger I don't care about the weight, I just don't want to vent and I don't drill holes in the body, just one of my policies.
I'm going to leave the starting battery and just slowly remove loads from it and put them on the "house" battery. Depending on how well it works I might just get a DC battery charger and charge my starting battery with the house battery. IDK yet.
The cap idea is going to be just pretty much a covering and after things fell in place it turns out it's going to be pretty easy, I'll do it for more professional looks if nothing else.
The tilt mount will just be some hinges and a prop type rod, I already maxed out my roof rack with the panels I bought so...



I thinks its coming together nicely
I built a frame for it, needs finished but its all cut out.

[Xringer]

That charge controller looks pretty nice.. In section 4.1.1 How MPPT Works, it describes how regular MPPT works and then explains how "TrakMax’s MPPT technology operates in a very different fashion"..
It's pretty cool the way the unit can use your panels in series or parallel, and still pull the max-power-point power out of them..

Series has the advantage of lower current (higher voltage) and less amps means you can use smaller wires from the panels to the controller.. Easier to install, and cheaper too..

[M_a_t_t]

Originally Posted by Xringer

That charge controller looks pretty nice.. In section 4.1.1 How MPPT Works, it describes how regular MPPT works and then explains how "TrakMax’s MPPT technology operates in a very different fashion".. I didn't actually read the manual I'll probably read it when I get it in my hand
It's pretty cool the way the unit can use your panels in series or parallel, and still pull the max-power-point power out of them..
I was gonna do series just because of the wires plus I didn't want to buy the connectors for parallel, but hey an extra plus!
Series has the advantage of lower current (higher voltage) and less amps means you can use smaller wires from the panels to the controller.. Easier to install, and cheaper too..

Matt

[saturndude]

Return the lithium cells. It does not make sense for this application, and they make it unnecessarily complicated.

Don't vent the lead acid, or put them in a sealed box with a small rubber tube going out the bottom out through pre existing grommet somewhere.

Billions of people have been fine living in closed quarters with lead acid batteries. I lived in my motorhome for 2 years with them under the couch. The only time it could realistically be an issue is if you connect an unregulated high power wall charger from the stone age.
The purpose of the solar charge controller is to regulate the battery voltage so it doesn't boil over and emit flammable gas. I am much more confident in a made in China controller than I am with a diy lithium back.

Put simply, the lead acid batteries are probably safer than the lithium batteries when it comes down to it.

The lead acid will be much cheaper, simpler, forgiving, and robust. Like 100% better in all those categories.

Lithium batteries are great for ebikes, electric cars, and portable electronics, but not optimal for this setup.

The only positive thing about the lithium batteries is that after you spend a ton of time and money and a little luck, they might last 2-4x longer. But thats best case scenario.

[M_a_t_t]

Sometimes I do things that don't make sense or may not work the best just because I can say I tried. I enjoy learning from my mistakes and if the lithium batteries fail for what I need them for then I'll know where to go next.

I'm ecomodding an Astro van for highway mileage when I only get on the highway about 6 times a year. Its more of an expensive hobby with a plus for me (and bragging rights ).

[saturndude]

That's cool, so do you plan to connect the one controller to all 4 banks at once? Are the lithium battery banks 12v?
I think you will need some additional circuitry to that mppt controller unless each lithium battery pack your buying has a built in charging circuitry.