Solar panel types and sizes, looking for input

[Geom]

Is it possible for Lithium and LA batteries to coexist is some workable configuration?

It might be possible to do so, but it will require a pretty convoluted configuration.
The two systems are completely incompatible and have entirely different charging profiles. Charging one with the other's profile can/likely-will damage it.

Also, drawing power from them is a challenge since they also have vastly different draw capabilities.

So, in essence, you'd have to have two discrete systems that don't interact with each other -which will double your costs for chargers and inverters.

But honestly, I think even a vastly smaller lithium bank will outperform any (aging) lead based system that you'd want to get rid of the latter post-haste.

[Mr. T.]

I'm in the early stages of designing a solar system for my bus; there's a LOT of
good information here!

I know that the maximum output from a solar panel occurs when it's tilted to an
angle roughly equal to your latitude (varies depending on time of year), but how
about the most practical installation in this case...  on the roof, pointed straight
up? How much capability do you lose?

What I'm working with here is five Siemen's panels, 105 watts each (i.e., 525 watts
in an optimal installation). In a roof rack, I'm cutting that in half; figuring 260 watts
seems reasonable to me.

Another issue is inverter capacity. Instead of one big inverter, I'm toying with the
idea of distributed inverters; a lot of small ones right at the point of use, and
just wire the bus for 12 VDC to feed them.

It seems to defeat the problem of putting all of the eggs in one basket; lose one big
inverter and you're dead in the water with all 110 VAC systems kaput.

Any comments on this scheme?

[richard5933]

Much bigger cable required for 12v to avoid heat and loss. Multiple inverter install might work if you keep them near the batteries and use longer runs of 120v Romax to avoid having long runs of 4/0 12v cable.

[Oonrahnjay]

Much bigger cable required for 12v to avoid heat and loss. Multiple inverter install might work if you keep them near the batteries and use longer runs of 120v Romax to avoid having long runs of 4/0 12v cable.   

        That, and multiple inverters are big money.  "Oh, a small inverter is inexpensive!"  No, not if it's unreliable, makes bad quality power, and has to be replaced often.  But there are lots of choices out there - you might be able to put together something; you obviously know your way around them electrictrons, so look at what's available. 

[Iceni John]

I know that the maximum output from a solar panel occurs when it's tilted to an
angle roughly equal to your latitude (varies depending on time of year), but how
about the most practical installation in this case...  on the roof, pointed straight
up? How much capability do you lose?

What I'm working with here is five Siemen's panels, 105 watts each (i.e., 525 watts
in an optimal installation). In a roof rack, I'm cutting that in half; figuring 260 watts
seems reasonable to me.

You may wish to read this about the importance of tilt:  http://www.solarpaneltilt.com/   That is why all my panels can tilt from 21 degrees down to 45 degrees up.

FYI, the standard derating for PV panels is about 0.7, i.e. a panel rated at 105W will produce about 70-something watts in real-life conditions.   Panels' STC ratings are based on insolation rates of 1000W/m2, but sunlight often is not as much as that.   Add in dust and dirt, leaves, bird poop, etc, and it's difficult to ever achieve STC ratings, especially if the panels are not oriented correctly.

John

[neoneddy]

Update for Everyone @ Mr T

I've decided to not sweat the type of panel (mono vs poly.   I stumbled onto this page (again I forgot) http://jdfinley.com/solar-charging-system-missy/   This is exactly the configuration I'll go for, big panels mounted side ways.   I found a local supplier who will take care of me pretty well.  Hopefully I can get him on camera for the channel.

I had planned for a 6 x 320watt panel configuration.   That might be overkill.   I'll for sure start with 4.

Mr T - The angle is important, but everything I've read says it often more trouble than it's worth.  I don't want to risk a panel flying off at 70 mph.    On the inverter situation I can tell you this.  I initially bought an AIMS 24v 3000 watt inverter.  It worked great for as long as it worked, my unit had a relay failure and stopped switching to grid / generator AC / charging mode.   It never stopped inverting which is good.    I would highly recommend sticking with a 24v bank and inverter.  It's 30% more efficient and you can use smaller wire, I already run 00 Ga wire.   Get a small 12v converter or I just run a wire from 1/2 of my batteries for 12v stuff.

I plan on doing  a full episode / video on this next topic. The one where I say "All you guys who say spend more now pay less later, you are right. " I'm ditching the AIMS inverter system and going full Victron. I have to say I think they offer the best all around system when it comes to Inverter + Battery Monitor + Solar Charger .  I recently learned they  Open Source their monitoring systems and support people building their own from RasberryPi  or just monitoring from the web interface. https://vrm.victronenergy.com/installation/1039/dashboard

Mr T , My honest Sincere advice would be to not skimp out on an Inverter / Charger ... Even find a Used Magnasine , Trace or Victron .

[Iceni John]

I've decided to not sweat the type of panel (mono vs poly.   I stumbled onto this page (again I forgot) http://jdfinley.com/solar-charging-system-missy/

His full write-up on The Other Forum (no, not BNO!) is well worth reading.   He's shown some drone photos of where he has boondocked, and solar is ideal for those locations.

I don't want to risk a panel flying off at 70 mph.

If it's securely fastened down, it won't fly off, ever!   I have a total of seventy-two 3/8" and 5/16" stainless socket-head bolts going through the roof ribs from underneath to hold my eight panels to the roof.   Heck, I could lift the whole bus up by the solar panels!*   Don't scrimp on the mounts, and you'll be just fine.

John

* Only a slight exaggeration . . .