OFF GRID POWER; various thoughts on...

[Mike 870]

Can anyone suggest a retailer that has a good mix of customer support for a self install and good pricing?  Starting to think about my system again.  Its basically going to be a stationary RV setup, but I'd like the option to run some power tools at times.  Loads would be water pumping from cistern (6ft of head, will use an 4.4 gal precharged pressure tank), on demand propane water heating, maybe a fan for a propane heater,  3 way dometic fridge, LED lighting, cell phone charging.  Weekend use except for a couple extended stays as time allows.  Good all day southen exposure on the ky/ohio border.  I already own a honda eu6500is generator.  I'd probably pay to oversize the system some. 

[MountainDon]

NAWS

[hpinson]

I've had good price and service from NAWS as well.

[Mike 870]

I'm really agonizing over which midsize charge controller to use. Anyone have any experience with the Morningstar PS, Morningstar Tristar, Midnight the kid, BlueSky SB, or Outback Flexmax 60?  Listed in no particular order.  I've been working with NAWS to size my system, and am coming up with a 12v 220 amp hour battery bank and 3 or 4 Kyocera 150 watt panels. 

My cabin is weekend use, and theft is a (small) fear, so for both reasons, I'm trying not to have thousands of dollars in equipment sitting out there.

[OlJarhead]

I have the Morningstar TriStar MPPT controller and while it works I've never been happy with it or their support.  My next will be an Outback.

[MountainDon]

I have used the FM60 and the Kid. Both work well.

Will there be an inverter? One thing I like when there is also an inverter is to keep the CC and inverter the same brand and networked together.  You can do that with Outback, but not most of the others. Xantrex has some that interconnect or network.  Another nice thing about the Outback inverters is the built in charger which can have its charge profile tailored to suit the generator used, if there will be a generator.

If you are in a lightning prone area also invest in good suppressors like the Midnite SPD's. Maybe look into an air terminal and ground plates/rods array as well if lightning is likely.

[Mike 870]

I'm kind of up in the air on an inverter.  With 2 6v 220 amp hour batteries it doesn't seem like it makes sense to try to power much AC stuff.  I go back and forth on it.  I already own a EU6500is generator, so it would be nice to have a quality inverter charger to maintain the batteries, but I worry that it will also lead others (cough, wife, cough) to be tempted to run loads the bank can't handle.   So I have been considering the idea of just using the generator when I need to run something on AC.

[Dave Sparks]

Been testing a very nice 300vdc CC from "begins with an O and ends with a K" Out very soon!

[MountainDon]

Cool. 

I'm still holding my breath waiting for "new" LiFePo4 news. 

[glenn kangiser]

I'm still liking my used forklift battery with multiple gigantic 2 volt cells to make 24 volts.  We used it hard this summer always using more power than we had panels, but it is back up to full charge since I quit running the 1.5 horsepower pump 1 1/2 hours per day or so.  Now only 15 minutes per day and acid shows full charge on hydrometer. 

[Dave Sparks]

Glen brings up a very good point that I can tie into Don and his curiosity of using Li-ion for offgrid. I will load a file her but it has always been a pain for me do this on this forum so I often don't. Not a big deal for me either way being a user of google photos.

One thing the chart shows is how well lead acid does with big loads like Glen is talking about. 1.5 HP.

The other thing I can say for anyone really wanting go this route is they need to be using a 48V inverter as there will be few choices at 24V nominal.
They probably will need an inverter that can have firmware updated at your site to be safely using this very new tech in an offgrid home.
It will be very expensive at first compared to 2V large capacity lead acid. I would guess prices getting better in 2018.
It is promising as anyone who picked up a Li-ion drill and been able to leave it dead for a month or more with a smile after charging knows.

[Mike 870]

I ended up going with a self selected setup that I got from Northern Arizona Wind & Sun. Its a Kyocera 150 watt panel, a Morningstar ProStar 30 PWM controller and a midnight babybox with midnight breakers.  I bought a 30 foot MC 4 cable that I cut in half. I unded up having to upgrade the controller so I could be over $500 and get free shipping.  At lrast this way I can add another panel if I ever want to.   Below is a picture of my setup.  I decided to affix some cable with anderson connectors permanantly to my battery compartment so I can easily connect and disconnect.  The cable is incredible stuff it is the size of 12 guage but the strands are so fine with so much surface area that it is rated for 60 Amps.  The Anderson connectors I used ate rated for 45 amps.  I'm going to mount all this either inside a pelican case or just on a nice piece of furnature grade plywood cut down to size with a handle routed into it. 

[Mike 870]

There we go, went faster than I thought.

[MountainDon]

   I like Casita trailers..   

[NathanS]

Has anyone looked into the Powerwall 2 that Tesla is supposedly going to start selling?

Kind of skeptical of the company, and not really a fan of how they market themselves.

It says 14kw and a built in inverter - which must be a high quality pure sine wave. $5500 for the battery+inverter and I believe it said something like $1600 for the installation - I don't know if this is labor + what kind of charging they are implying - I'm guessing grid tied?

Anyway, I mainly bring it up because $5500 for 14kw of AC in lithium ion batteries and a pure sine wave inverter seems like a pretty drastic price drop from what I was seeing a few years ago. I think that this is roughly equal to 26 golf cart batteries? Someone might need to check my math there. $2600 of golf cart batteries that will last 7 years at most vs lithium ion which includes a 10 year warranty and aren't those expected life spans closer to 20-25 years?

Other advantages, there is no venting necessary or wiring all the batteries, much less space taken up.

May not make a big difference for a full time off grid set up, but as these lithium ion prices come down it seems possible to create a backup system that includes solar and wind in addition to a generator.

Side note
Tesla batteries in their cars are simply Panasonic computer batteries that are wired together in a special way. I had looked into this at one point because Panasonic stock may be a steal right now if Tesla's meteoric rise is sustainable.

[DaveOrr]

I think they're going to keep going up.
They just purchased Solar City so they can produce their solar roofing shingles.
They say their new shingles will not cost much more than a regular shingle job (after factoring in useful life, energy savings etc.) but turn your entire roof into solar panels but it just looks like a regular roof.


Tesla is even powering a whole island!!!

http://www.theverge.com/2016/11/22/13712750/tesla-microgrid-tau-samoa

[MountainDon]

They say their new shingles will not cost much more than a regular shingle job (after factoring in useful life, energy savings etc.) but turn your entire roof into solar panels but it just looks like a regular roof.

I think that needs some more checking into.  I believe the comparison to "regular" roofing was not to our nearly ubiquitous asphalt shingles but to more expensive tile roofs which the tesla solar roof looks like.  Tesla pictures 4 types and all appear lsimilar in appearance to 4 different tile or slate roofs. Don't believe the $$ comparison is to ashphalt shingles until you see the actual product pricing and what instakllation requirements are.   Just my skepticism showing through....

[DaveOrr]

I think that needs some more checking into.  I believe the comparison to "regular" roofing was not to our nearly ubiquitous asphalt shingles but to more expensive tile roofs which the tesla solar roof looks like.  Tesla pictures 4 types and all appear lsimilar in appearance to 4 different tile or slate roofs. Don't believe the $$ comparison is to ashphalt shingles until you see the actual product pricing and what instakllation requirements are.   Just my skepticism showing through....

Actually it was to asphalt but they factor in the longevity of the roof, the payback over their life etc.
Initial outlay is 3.5 times the cost of regular shingles. But regular shingles would need replacement 3 times during the life of Teslas roof.
So they say.

[Dave Sparks]

The whole thought of connecting all those very low voltage panels in series is not something anyone living offgrid would want to do no matter how the connection is made.
If you live on the grid it is nothing but money that you are risking with schemes like that. They say the connection method is easy and it will last. Offgrid in some of the places I go there are very few people to help you and so the owner must make servieable and intelligent choices.

When the fire people rate that kind of roof and it gets tested over time by early adopters, I might think about it for a barn roof offgrid. Certainly not the roof of an offgrid home.

[hpinson]

That's a really good point. Serial connection of all those little panels, and exposure to extreme heat and cold over time with corresponding expansion and contraction and corrosion. It makes me think of a long string of Christmas lights where one goes out.  How do you identify and replace?

[Dave Sparks]

The whole thought of connecting all those very low voltage panels in series is not something anyone living offgrid would want to do no matter how the connection is made.
If you live on the grid it is nothing but money that you are risking with schemes like that. They say the connection method is easy and it will last..... Offgrid in some of the places I go there are very few people to help you and so the owner must make serviceable and intelligent choices. It is just too easy now to use (10) 45V solar panels in series and have zero problems for 30+ years.
Imagine having strings with 80+ panels in series
Imagine having to find the bad panel?

When the fire people rate that kind of roof and it gets tested over time by early adopters, and the loss of efficiency of not having cool air under the panel, I might think about it for a barn roof offgrid. Certainly not the roof of an offgrid home.

These solar tiles have been around(other companies) for 10 years now and none of them have been good for a typical home.  Maybe someone will do this right because it does make sense for grid-tied solar, I just would not hold my breath!

[Mike 870]

Hey Dave,

         I see that you have a lot of experience with tracking mounts.  I have a couple basic questions about them.  I've done some reading on them and like some of the benefits they bring to the table.  I'm starting to think about my cabin system which I will probably be ready for in late summer. 1) Do you use mostly single axis passive trackers like the zomeworks?  How does tracking impact this general rule of thumb when sizing panels to a bank (Bank AH) x charging volts x1/.77x8-15%.  Meaning since you're tracking, should you design to less array size?  Last question, would it be poor design to have 2 panels on a tracker and two panels fixed to a roof?

My hypothetical system would kind of be in a funny spot. On the small side, but really close to needing a bigger charge controller than the more affordable 30amp controllers or upping battery bank voltage to 24 and using a step down. 

[OlJarhead]

While we wait for Dave I read somewhere, long ago mind you, that solar trackers add only about 25% to production and cost more than adding more panels.  When looking at my system I was able to buy 6 new panels for the price of a solar tracker.

Doing it yourself is different if you have the wherewithal.

[MountainDon]

Trackers are still very nice when you want to operate something like a mini split for A/C or heat.  Early AM can be enough to get the SOC up and then in the afternoon there are hours of power for the mini split or whatever.

[Bob S.]

What happened  to the home-built tracker that Glenn made?