Critique CycleCruza's 400W System

[grimshade]

Greetings all,

These are some of the best videos on solar-installs I've seen!

The first video shows CycleCruza's Paralell 400 Watt -- 40A MPPT - 2000W inverter - 310ah battery system. The second shows his revisions after a year, which mostly include making his own wiring in a more affordable way. 

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Do you folks see any issues with this set-up? Strikes me as ideal for my needs. I'm currently drawing the layout and will post it when I'm finished, if anyone's interested. 

 

[MazdaGuy15]

From what I have read you want to wire the panels in series NOT parallel so that you can get above 12v (24-36v) going to the mppt controller which will reduce the volts and raise the amps going to the batteries. Then you can use cheaper smaller wire since the amps are lower. And when the panels are shaded you will still have above 12v (where he could have less than 12v going to the controller to charge the battery)

 

[MazdaGuy15]

I'm still in the planning stage but I will probably buy the panels and controller separate and make my own cables without those fancy connectors that look like water will get into.

 

[John61CT]

Only downside to serial is it increases the extent any shading, stray leaf or twig on a single panel, will cripple total output.

Ideal is lots of separate controllers but $$$.

Personally hoping Maxim's MX technology works and becomes available here at retail.

 

[KMAG YOYO]

Ideal is lots of separate controllers but $$$.

Never heard of this approach, does it work? Seems like the separate controllers could confuse each other and inaccurately read the state of charge.

 

[John61CT]

These are IC-level mini MPPT controllers designed to embed within panels or junction box wiring.

Also replacing what the diodes do between strings. See also DC optimizers, micro inverters.

Specifically designed to improve PV's currently woeful handling of shade issues.

They would feed into the main controller charging a bank.

 

[29chico]

Flexible panels glued on the roof?  Those panels will get really hot w/o an air gap below them to dissipate heat and efficiency will suffer.  Flexible panels don't last as long as rigid panels and getting cooked on a roof will make that even worse.  An air gap on the roof will also really help with keeping the heat out of a rig by shading the roof.  My cargo trailer's roof is totally covered by the solar array, this also keeps rain out of my roof vent as it is right under a large grid tie high voltage panel.

Series vs parallel:  Why not get a big 400w, or more, grid tie high voltage single panel since you are thinking of going with MPPT anyway?  A buddy of mine has a very nice single 435w panel install.  Just be sure that the MPPT controller is rated for the max voltage of the panel.

About the Vmax AGM's, cut and paste from another recent post of mine:

If you are a solar beginner I suggest a couple of 6v golf cart batteries from Costco at around $86 each.  If you are somewhat confidant that you won't commit batterycide right away I suggest the made by East Penn Duracells from Batteries + at about $109 each.  I don't suggest AGM's unless one is skilled and I don't suggest the Vmax AGM's at all.  For a bit more money high end Lifeline or Northstar AGM's are a whole lot better battery.  The Northstar AGM's are sold at Batts + as X2 Power with a 4 year warranty.

 

[jimindenver]

I agree that series would be better but it would be two panels in series and two sets of panels in parallel. You Want higher voltages but not too high that it effects the efficiency of the controller.

I have used as many as three controllers in parallel to one bank. The biggest issue was getting them to all see the same voltage. Otherwise as long as they are all set for the same set points it's fine.

 

[John61CT]

You want higher voltages but not too high that it effects the efficiency of the controller.

Depends on the controller, the Victron docs state that having multiple panels to give a higher voltage actually helps the MPPT efficiency.

Multiple controllers to one bank doesn't sound optimal to me.

 

[MazdaGuy15]

If I get one 250w 24v panel and have a mppt controller would it in theory put 500w at 12v to the batteries? (probably more like 400w at 14v)

like this panel?
https://www.amazon.com/Solar-Monocr...id=1488049418&sr=8-2&keywords=24v+solar+panel

 

[minimotos95]

Ideally with multiple controllers they are set up as "slaves" to a main controller.
Watts stay about the same but you get less loss and a 24v panel pushes roughly half as many amps as a 12v panel of the same wattage so you don't need as big of charge controller.

CC was an active member on here for a month or a few a while back. I can't recall what username he used though?

 

[jimindenver]

If I get one 250w 24v panel and have a mppt controller would it in theory put 500w at 12v to the batteries? (probably more like 400w at 14v)

like this panel?
https://www.amazon.com/Solar-Monocr...id=1488049418&sr=8-2&keywords=24v+solar+panel

Watts are watts. At 24v you will push a higher voltage but half the amps. You need bigger wires to push 30 amps at 12v than you do 15 amps at 24v.

 

[John61CT]

I really don't like all that kludgey wiring mess up on the roof, would probably use thicker wiring direct from the panels and keep all connections inside.

He said nothing about the need for UV resistant insulation, purpose-made solar wiring stock would be worth it.

Backing the panels with flexible double-walled plastic board, also UV resistant maybe greenhouse panels, would give an airgap to reduce the heat gain without mounting hardware - expensive, kills stealth and fuel efficiency.

I'd also use HD industrial velcro or an adhesive that allowed for removal of the panels.

One idea I'm considering is a maximum area but low-profile roof rack. Obviously the panels could fill the rack, but then if you want to carry stuff you'd have to unload it all whenever you want power.

What about utilizing the space between the van roof and the rack, and slide semi-rigid max-area sheets full of these "flex" PV panels out from under?

I understand there are even PV vendors that will build custom size panels to your spec to maximize watts per sq ft.

Maybe poles, sheets double as a shade canopy, or pull foward, lean over the windscreen & hood area. Or long enough wiring, park in the shade, panels out in the sun?

Just need a good containment system for the huge sheets, maybe pull the edges up tight to the floor of the rack above?

And need something to stop the van roof getting scratched up. . .