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StephenH View Drop Down
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Direct Link To This Post Topic: Micro-Air easy start
    Posted: 18 Sep 2019 at 8:49am
That green color reminds me of a pickup camper that my dad built many years ago. It was a bit larger IIRC, with a bed above the cab. Later, they sold that and bought a commercial one that was even larger. I probably have pictures of it somewhere. What you built looks pretty good. It will be interesting to see a picture of it when it is finished.

Edit:  Nice web site. Thumbs Up
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Direct Link To This Post Posted: 18 Sep 2019 at 9:10am
Originally posted by offgrid

On the low light thing, there ain't no free lunch. 

You are so right on this!

Beyond that, knowing that Vmp will still be pretty low at low irradiance, you can use a MPPT to extract as much power as possible. That's the basic physics of PV devices, not something you can change, so I don't see what additional electronics can do for you. 

The two working on that portion had thoughts leading back to the Frequency/back feed recovery circuit they had devised. That was way over my head, yet they were into it.

Since low light implies diffuse light, you can tune the glass ar coating to enhance light collection at high incidence angles. That's probably what your coatings guy was working on. There are also spectral differences under low light conditions, so in theory you could tune the cell ar coating to improve low light collection, but in practice you don't really want to hurt your direct high irradiance performance in the process because even in a cloudy place most energy collection comes on clear days as direct not diffuse. 

Again, so correct. The balance was important. Basically it was becoming a  MPPT on steroids. Yet in direct sun, it had reduced input. The exercise was mainly low light/cloudy conditions.

Are you putting solar on your sleeper cap? Looks like a nice flat surface up there for it. 

No, it's just a Sleeper Cap. I wanted something I could Overland and stay for the night. I will have my portable lithium power back for lighting and basic re-charging. 


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Direct Link To This Post Posted: 18 Sep 2019 at 9:12am
Originally posted by offgrid

On the low light thing, there ain't no free lunch. 

Bottom line is that PV cell/module Isc varies linearly with irradiance (more photons= more current). As you can't extract any power at Isc, the only thing you can do is to get modules made with the best quality cells you can.  That way they have low shunt resistance and as high a fill factor as possible so that their Vmp and efficiency doesn't fall off dramatically at low light levels. High quality mono cells work best. 

Beyond that, knowing that Vmp will still be pretty low at low irradiance, you can use a MPPT to extract as much power as possible. That's the basic physics of PV devices, not something you can change, so I don't see what additional electronics can do for you. 

Since low light implies diffuse light, you can tune the glass ar coating to enhance light collection at high incidence angles. That's probably what your coatings guy was working on. There are also spectral differences under low light conditions, so in theory you could tune the cell ar coating to improve low light collection, but in practice you don't really want to hurt your direct high irradiance performance in the process because even in a cloudy place most energy collection comes on clear days as direct not diffuse.

Our earliest panels were from a company called SunWize. Where we are on the west coast, and close to it, we get a lot of days with diffuse light because of the frequent fog/marine layer. Those panels and the PWM controllers we used at that time just did not deal well with those conditions, and we often had to compensate for that frequent fog.

Later on, we switched to some Trina panels (yes, Chinese made) and (still PWM) controllers. Wow, those panels really worked well, even in the fog. We even set the panels for a fairly high angle ~~ 50 degree tilt. Even though summer sun was off-angle, and often in the fog, those suckers just cranked electrons. In the winter, when the fog is not as persistent, they worked even better.

Still later on, we switched to MPPT controllers, and things got even better. The MPPT controllers allowed us to string together several panels and increase the overall voltage. So even if the panels were only producing 25 or 30 percent of rated, the MPPT controllers allowed us to extract what was available. With the PWM controllers, the panels had to be at around 75-80 percent before we could extract anything.
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Direct Link To This Post Posted: 18 Sep 2019 at 9:16am
Originally posted by StephenH

That green color reminds me of a pickup camper that my dad built many years ago. It was a bit larger IIRC, with a bed above the cab. Later, they sold that and bought a commercial one that was even larger. I probably have pictures of it somewhere. What you built looks pretty good. It will be interesting to see a picture of it when it is finished.

Edit:  Nice web site. Thumbs Up

Thank you and thank you! The purpose of this build was two fold. I want a over-night style camper I don't have to tow and I wanted to learn this foam built system. 


It been a great learning process and I like the system. Several things I would do different, LOL, learning curve thing!


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Direct Link To This Post Posted: 18 Sep 2019 at 9:31am
Originally posted by Olddawgsrule

The two working on that portion had thoughts leading back to the Frequency/back feed recovery circuit they had devised. That was way over my head, yet they were into it.

No, it's just a Sleeper Cap. I wanted something I could Overland and stay for the night. I will have my portable lithium power back for lighting and basic re-charging. 
 


Frequency/back feed recovery sounds a bit like perpetual motion to me. PV cells are just big ol' diodes, ie, they are dc devices. They work best if you keep them at a stable operating point on their IV curve and you can't get more energy out of them by dithering with that once you find it for a given set of conditions, which is what the MPPT does.  In fact fiddling with that operating point will inevitably reduce performance. And if you back feed a solar module it absorbs energy.  We actually made roof solar arrays that doubled as a snow melt system by back feeding them at one point. Dumb, yes i know, but the customers wanted it. 

Once you get your trailer back the top of the cap might be a good place for a big PV module, looks like you have a larger available surface area there than on the trailer roof.  Add an MPPT and long cable and you could park the truck in the sun while the trailer stayed in the shade. Just a thought....


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Direct Link To This Post Posted: 18 Sep 2019 at 10:26am
Originally posted by offgrid

 
 


Frequency/back feed recovery sounds a bit like perpetual motion to me. PV cells are just big ol' diodes, ie, they are dc devices. They work best if you keep them at a stable operating point on their IV curve and you can't get more energy out of them by dithering with that once you find it for a given set of conditions, which is what the MPPT does.  In fact fiddling with that operating point will inevitably reduce performance. And if you back feed a solar module it absorbs energy.  We actually made roof solar arrays that doubled as a snow melt system by back feeding them at one point. Dumb, yes i know, but the customers wanted it. 

Once you get your trailer back the top of the cap might be a good place for a big PV module, looks like you have a larger available surface area there than on the trailer roof.  Add an MPPT and long cable and you could park the truck in the sun while the trailer stayed in the shade. Just a thought....


[/QUOTE]

The Frequency/back feed wasn't to the panels. I agree, that doesn't work. That's were the electronic's to the battery came in. Like a MPPT on steroids or so was the concept. 
The concept came from the Open coil/transistor build they did. That started as a better charging system yet turned into a great battery maintainer. Many of the same principles are in the better commercial battery maintainers you can buy off the shelf now. Theirs was built to maintain a larger battery bank (mainly LA's). 
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Direct Link To This Post Posted: 18 Sep 2019 at 10:36am
Originally posted by Olddawgsrule

Originally posted by StephenH

That green color reminds me of a pickup camper that my dad built many years ago. It was a bit larger IIRC, with a bed above the cab. Later, they sold that and bought a commercial one that was even larger. I probably have pictures of it somewhere. What you built looks pretty good. It will be interesting to see a picture of it when it is finished.

Edit:  Nice web site. Thumbs Up

Thank you and thank you! The purpose of this build was two fold. I want a over-night style camper I don't have to tow and I wanted to learn this foam built system. 


It been a great learning process and I like the system. Several things I would do different, LOL, learning curve thing!
Thanks. I like the idea, but lack the place in which to do likewise.
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Direct Link To This Post Posted: 18 Sep 2019 at 12:19pm
Originally posted by Olddawgsrule


The Frequency/back feed wasn't to the panels. I agree, that doesn't work. That's were the electronic's to the battery came in. Like a MPPT on steroids or so was the concept. 
The concept came from the Open coil/transistor build they did. That started as a better charging system yet turned into a great battery maintainer. Many of the same principles are in the better commercial battery maintainers you can buy off the shelf now. Theirs was built to maintain a larger battery bank (mainly LA's). 

Ok, so some form of pulse or variable charge rate battery charging. I'm not going to debate that one, there are all sorts of opinions out there about how best to and not to charge a PBA battery. But that's not really about maximizing PV ouput at low light levels. For that ar coatings are probably the most practical approach. Many if not most module manufacturers use ARC glass already. 
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Direct Link To This Post Posted: 26 Sep 2019 at 10:37pm
Just did the same. Very happy now.
The situation was bad. Purchased the yamaha 2000is v2 pair with parallel cable. Overloaded generators in every permutation I could come up with. The A/C would not start. Today, happy to test and could not overload the genies with several scenarios running A/C. I was pissed about the yamaha performance, now I think it was the (and I will get this wrong) lock start amperage of the dometic unit causing the issue and overloading the generators. I can start A/C with eco mode, run the microwave, fridge, water heater, pump, etc.

First post. Wish I read this sooner. Bought the 195 in August 2019.

I paid $200 ($500 total, including the 364) for the installation of the micro-air 364 instead of scaring my girlfriend to death with DIY. Micro-air recommends rv spots nation wide, and one was close by NW Houston.
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Direct Link To This Post Posted: 04 Aug 2020 at 3:19pm
Just bought the micro-air easy start for our 2017 179. I have a Westinghouse Igen4200 inverter generator. I’m shocked it can’t power it reliably but at any sort of elevation (4-6k) when hot out the AC will overload it. We have a 1 year old, so AC mid-day for naps is a necessity. Last weekend we had to idle the truck so he could sleep.

Any good instructional videos on installing one of these? I found one YouTube video but it is not on an Rpod.
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