DC Solar trailer used for charging my M3

[nwdiver]

Is it possible they just have a single bypass diode and a single group, or is the reverse-bias breakdown too low on the diodes to make that possible?

Super unlikely. I've never seen a solar panel with fewer than 3 bypass diodes. It would be a fire risk. Shaded solar cells become a load. If there isn't a way to divert current around them they get hot. REALLY hot.

 

[jjrandorin]

Just a gentle reminder that this is now not discussing the OPs trailer, but shading on your solar install, @AlanSubie4Life

 

[AlanSubie4Life]

Just a gentle reminder that this is now not discussing the OPs trailer, but shading on your solar install, @AlanSubie4Life

Yeah, I was nearly done (it was related, though distantly, and I was coming full circle, eventually)! Thanks for all the info @nwdiver. Sounds like given what we have now been presented with, the shading on the OP's trailer is not likely to cause major issues with output (as he indeed reported). We'd expect a 33% output cut (EDIT: maybe not...looking at the panel orientation. Never mind).

 

[nwdiver]

Just a gentle reminder that this is now not discussing the OPs trailer, but shading on your solar install, @AlanSubie4Life

He should have taken a photo closer to noon As an aside and a bit more on topic.... those panels are probably wired in series-parallel (4S2P) which means in this photo the output of the rear panels is likely 0.

 

[AlanSubie4Life]

He should have taken a photo closer to noon

Remember that these panels rotate to wherever you want the angle to be.

He should have just rotated the panels to be basically flat, and avoid the shade in his picture, so I didn't get so stressed about the inefficiency of it all. Or taken it later in the day as you say. (His angle might will be optimal for integrated generation, you want the panels to be as close to perpendicular to solar incidence as possible, which is easy if you have just one bank - but the shading effect would need to be taken into account to determine that optimum if you were generating a table. And the optimum angle would need to be defined as to whether it was a fixed setting for the day, or whether it could be adjusted through the day, or whether it was set once and forgotten, etc. Etc. Etc. )

those panels are probably wired in series-parallel (4S2P)

I have noticed a small drop in solar production when one panel bank shades another, but it is not a deal or current killer.

Each panel is equipped with its own micro inverter, which helps.

Shrug.

 

[crazyrudy]

He should have just rotated the panels to be basically flat, and avoid the shade in his picture, so I didn't get so stressed about the inefficiency of it all. Or taken it later in the day as you say. (His angle might will be optimal for integrated generation, you want the panels to be as close to perpendicular to solar incidence as possible, which is easy if you have just one bank - but the shading effect would need to be taken into account to determine that optimum if you were generating a table. And the optimum angle would need to be defined as to whether it was a fixed setting for the day, or whether it could be adjusted through the day, or whether it was set once and forgotten, etc. Etc. Etc. )





Shrug.

Sigh. Shrug. Sigh. Where do I begin here? Uhm....wow. 4S2P, really? What photo are you looking at?

 

[crazyrudy]

Remember that you have not only the rotation axial, but also the rotation level, which gives you a different universe of angulation. That means that shading can be perpetually avoided. "Open your mind"

 

[AlanSubie4Life]

Sigh. Shrug. Sigh. Where do I begin here? Uhm....wow. 4S2P, really? What photo are you looking at?

I didn't say 4S2P. Anyway, it looks like a great trailer. Seems wonderful for your situation (and a good deal too). I was just curious about whether you had noticed any major shading issues, but in the end the sun angle will typically be high enough this won't be much of a problem, and the angles can be adjusted separately, anyway.

but also the rotation level, which gives you a different universe of angulation

Awesome. Sorry if I didn't sound open minded; I was just curious about this specific aspect. It wasn't a criticism. It sounds like it doesn't impact much, and it's relatively easily mitigated if you wish.

 

[crazyrudy]

Well,

I didn't say 4S2P. Anyway, it looks like a great trailer. Seems wonderful for your situation (and a good deal too). I was just curious about whether you had noticed any major shading issues, but in the end the sun angle will typically be high enough this won't be much of a problem, and the angles can be adjusted separately, anyway.




Awesome. Sorry if I didn't sound open minded; I was just curious about this specific aspect. It wasn't a criticism. It sounds like it doesn't impact much, and it's relatively easily mitigated if you wish.

Well, I am just asking for a broader understanding in the discussion. It would not be correct to make all of the assumptions about shading in a permanent mount and applying that to a mobile mount. Isn't that the cool point of the trailer? That it makes shading and angling just a matter of a few cranks on a lever, or the skills of a two-beer parking job? We are free of the bonds of a (semi) permanent mount, and it is all just a matter of relative perspective that can be easily adjusted. That, my friends, is the true unlocking secret of solar energy...when max efficiency can be easily achieved wherever you are. It is so much better than an .01% efficiency increase here and there, it is magnitudes better. Also, just sayin'...it could be the christmas nogg talking..so there is that....cheers!

 

[AlanSubie4Life]

Well, I am just asking for a broader understanding in the discussion

I understand the concept is generally quite flexible. Ideally you'd have automatically controlled mechanical actuators on all of this stuff so you didn't have to mess around with it and it would optimize itself!

Also, just sayin'...it could be the christmas nogg talking..so there is that....cheers!

Merry Christmas!

 

[crazyrudy]

A quick update to the solar effort. The M3 is now drawing from 3 solar trailers (30 panels, 3 battery banks, 6 inverters, 13kW dual fuel generator). The trailers now backfeed excess energy to the grid. I have learned so much since the original post, and have implemented many efficiencies along the way. I produce a lot of energy everyday. I use what I need and send the rest back to the grid. I have a complete home backup power supply when the grid is down. I fuel my two EVs from the sun.

 

[ScottNY]

Rooftop solar also powers your home, and is likely a lot more power than that rig would generate... but maybe it generates more than I think.

…and costs significantly more than $5K

 

[crazyrudy]

One more thing about this installation....
It is a mash up of different PV, battery, and generator installations. So how to keep track of it all? The rooftop solar is SolarEdge, and the app tells me what it is producing. But the contribution of the trailers was a bit of mystery beyond the theoretical calculations of output. Also, I did not know what the "net" production was because I was not tracking the draw from the EV's and the home. All I knew was at the end of the month I had no power bill, and the power company told me I had banked so much energy credit. Not very helpful for inquiring minds.

Enter the Github project GitHub - David00/rpi-power-monitor: Raspberry Pi Power Monitor . Super easy, and David was a very helpful and knowledgeable guy. Here is the resulting Grafana display for last week:

The main grid power is registered on CT0 and CT1, trailer power on CT2 and CT3, rooftop solar on CT4 and CT5 (graph from yesterday):

So, now I can monitor EV charging from a panel draw perspective. This helps a great deal when dealing with grid connected inverters, and direct connect to power trailers for EV charging.

 

[crazyrudy]

Why?

Slightly delayed reply here. There are a lot of reasons for this...load balancing the trailer output, load balancing all solar input sources for positive output to the grid while charging, life cycle of the trailer batteries, life cycle of the EV batteries...to name just a few.