Author Topic: OFF GRID POWER; various thoughts on...  (Read 584626 times)

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Offline old_guy

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Re: OFF GRID POWER; various thoughts on...
« Reply #1500 on: September 19, 2019, 09:13:02 AM »
Its been too quiet for a while here on countryplans.  A good time for me talk about solar.

We started building in NE Tennessee in July of 2017.  We got the walls framed and partially sheathed, and the roof sheathed and covered with underlayment, before that winter.  Wall sheathing completed, some windows in, half the building wrapped, and metal on the roof in 2018.  We now have stairs to the second floor and most of the windows in.  We hope to get the siding on this year and begin moving in next summer.

It is over 1.5 miles of gravel road from the house to the pavement and power lines.  A mile of that is on an easement along the property line between 2 neighbors, the remainder through our own land.  The power company wants $7/ft to bring in power.  So, $55,000 PLUS purchasing easement(s) from the neighbors, and clearing those easements, to get power brought in.  Brought in through the forest, where every breeze blows down a limb.  Uh, no thanks.

We got serious about solar this spring.  I had read everything I could find for a very long time, and learned a lot, but was very aware that there was much more to know.  I sent an email to our Dave Sparks, got a quick reply, and soon found myself telling him “let’s do this!”,

Our Tennessee location has its challenges.  We are on top of the hill, but in what is basically a notch in the forest.  Tall trees on the east and west sides of our clearing, as well as neighboring hills, block both early and late sun.  With clear info on our site Dave helped us find a good panel configuration and array locations, and he determined good electronics to support it.

I spent 3 weeks there in July, installing a water system, receiving the shipments of solar equipment, and starting the solar install.  We installed and wired up the electronics and the batteries, built the ground mount for some of the panels, and ran the wires from array to house.  As always, I needed one more day, and did not get the panels installed.  My son and neighbor continued working on it and, 2 days later, sent me a photo of the readout showing we were generating almost 2900 watts.  Woo-Hoo!

The system is 48 volts (batteries), with 27 310-watt panels planned (only 9 installed so far).  We planned to have 24 2-volt batteries, but the distributor could not meet his delivery promises, so we are temporarily using 8 6-volt 210 Amp-Hr golf cart batteries.

With just 1/3 of our panels installed, and using batteries with only 1/5 the planned capacity, the solar has changed everything.  We can run a huge 120V window A/C, an old full-sized refrigerator, all the lights and stuff we could want, and still charge the batteries to float every day.  We must turn off the A/C as soon as the sun gets too low or it will deplete the batteries.

And QUIET, without the generator running.  We had been using about 10 gallons of gasoline in the generator every day before turning on the solar.  I just spent a week there and did not use even the 5 gallons in the generator fuel tank.  What little I did use was only because I had left the AC running too long after sunset and wanted to top up the batteries.

I started frequenting CountryPlans years ago for the building info, and have learned and applied much from here.  The OFF GRID POWER thread became more important as I was ramping up our solar plans, and Dave was a welcome bonus.  I am retiring next summer and moving then to our Tennessee home.  Thanks to everyone here for your help along the way.

Offline MountainDon

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Re: OFF GRID POWER; various thoughts on...
« Reply #1501 on: September 19, 2019, 09:36:07 AM »
I'm happy to hear you hooked up with Dave. He knows his stuff and is good to work with.  Solar sure beats gasoline any day.   ;D
Just because something has been done and has not failed, doesn’t mean it is good design.


Offline hpinson

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Re: OFF GRID POWER; various thoughts on...
« Reply #1502 on: January 13, 2020, 07:49:13 AM »
I thought this tutorial very interesting: DIY 12v 100Ah LiFePO4 Solar Battery for $555

https://youtu.be/vTFLuKjvUQw



Offline Dave Sparks

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Re: OFF GRID POWER; various thoughts on...
« Reply #1503 on: January 16, 2020, 01:43:44 PM »
Nice video and it does show the pricing is still not there for LFP. Consider you can buy a similar battery at costco for less than $100 and have a warranty.
The costco battery may not last as long but who knows how long this DIY will last. Also how good will this be if overcharged or discharged since there do not appear to be any specs.
"we go where the power lines don't"

Offline MountainDon

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Re: OFF GRID POWER; various thoughts on...
« Reply #1504 on: January 16, 2020, 06:02:20 PM »
I've seen a couple other videos from that guy. Pretty good. One thing that I noted that made me wonder though was how he used two band clamps (hose clamps) to hold the cells together. He mentioned that prismatic LFP cells can swell. The packs I have seen sold by companies that sell batteries assembled from prismatic cells all used metal plates that were then held by band clamps or some other sort of straps. From what I understand these cells can develop quite a "bow" under some conditions if not properly restrained. Makes me wonder if his method is too much of a shortcut?



Some of the prismatic cells are now made using aluminum outer cases instead of the plastic. FYI, those appear to be CALB cells; one of the big names in Chinese LFP. (CALB = Chinese aircraft lithium battery)

He mentioned having had problems with BMS units that did not work.  Someone I know in CO built himself a similar LFP battery for his travel trailer. He bought the cells and a BMS from a stateside seller. The first BMS he received along with the cells did not work right out of the box. He got a replacement sent quickly at no charge. But that was disconcerting. His system does incorporate a couple of large HD disconnect solenoids that are controlled by the low and high voltage sensors.

Overcharge can kill LFP much quicker and with greater finality than lead-acid. Must admit that lead acid are very forgiving compared to litium.

 I'm going to keep watching what is happening in the lithium battery field.  I got new lead-acid batteries last year and am good for a few years. The one thing I like the best about LFP is they can sit for months on end in a partial charge state, not being used, not being charged,  and not be damaged.

A downside is they are so much lighter they are more likely to be stolen than lead-acid.
Just because something has been done and has not failed, doesn’t mean it is good design.


Offline Dave Sparks

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Re: OFF GRID POWER; various thoughts on...
« Reply #1505 on: January 22, 2020, 03:22:26 PM »
I think something better will come out. IBM has patents on a new type of cell that will not use the expensive heavy metals.
To me the major downside of LFP is you can't charge them below 32. Well, you can once :(
"we go where the power lines don't"

Offline ChugiakTinkerer

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Daily energy consumption
« Reply #1506 on: January 21, 2021, 03:00:16 PM »
Might try and wake up this thread....  ???

Dear wife and I are getting serious about the get-away cabin and I'm now pricing a solar installation.  One problem I have is realistically estimating our energy needs.  Right now we are at two extremes: our house in Anchorage uses upwards of 30 kWhr per day in the winter.  Much less in the summer, although we heat with natural gas.  When at the cabin our current uses is probably in the single digits of watt-hours per day.  Definitely under 100, but all we do is run a few headlamps and two CPAP machines.  I can only guess what our needs will be when we have the cabin completed and spend months at a time there.

Based on my guesses I've gotten a quote for a 1300 W array @ 24V with a 4000 watt inverter.  Four 415 A-hr Rolls batteries at 6V.  I'm thinking this is overkill (not a bad thing) but I have no clue by how much.

Does anyone have a system that reports their daily energy use?  if so, what numbers do you see and for what sort of appliances?
My cabin build thread: Alaskan remote 16x28 1.5 story


Offline ChugiakTinkerer

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Re: OFF GRID POWER; various thoughts on...
« Reply #1507 on: February 14, 2021, 07:21:52 PM »
I'm becoming more informed, and realizing the more I learn the less I know!   ???

I'm looking at a fairly small array, four to six 60-cell panels most likely.  I want to do a top of pole mount, but one thing I am running into is the challenge of sinking a deep enough hole to properly anchor a 4" pole.  My calculations show I need to get the hole down to seven feet, but the best I can muster with my hand-operated power auger is about four to four and a half feet.  That's barely adequate for a two-panel topper, so maybe the solution is to have two or three poles.

Any other ideas for how to mount six panels?
My cabin build thread: Alaskan remote 16x28 1.5 story

Offline Nate R

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Re: Daily energy consumption
« Reply #1508 on: February 15, 2021, 07:41:55 AM »
Might try and wake up this thread....  ???


Does anyone have a system that reports their daily energy use?  if so, what numbers do you see and for what sort of appliances?

I use a Trimetric 2030 to monitor battery juice. Been happy with it to give me live updates on current draw, or daily battery AH. 

I also use a Kill-A-Watt for 120V devices. $20-30 for one, and they work awesome for watt draw and totalizing watt hours over time. They do NOT do well at high currents for long periods. (I'd not put 1000W through one for a long period of time.) Seems the fuse is a bit undersized.    But for seeing how much your CPAP uses overnight, that'd be perfect.

Also, my Morningstar Prostar charge controller gives me the daily AH put into the batteries. And a downloadable history. So I can average out my sun hours over time for my location, or see the worst day, or how low my battery voltage got overnight, etc.


Offline Nate R

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Re: OFF GRID POWER; various thoughts on...
« Reply #1509 on: February 15, 2021, 07:44:16 AM »

Any other ideas for how to mount six panels?

I had the same thoughts as I was designing my bigger/permanent system, before I opted to go on the grid.

I was going to do a wood-post mount system. But I didn't need much height, just the right location. Like a few 4x4s or 4x6s and some crossmembers to hold the panels.

Offline MountainDon

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Re: OFF GRID POWER; various thoughts on...
« Reply #1510 on: February 15, 2021, 01:17:33 PM »
I have a small three panel pole top array we installed in 2009. I hand dug a hole with shovel and a post hole digger ( clamshell type) to get to the 5 feet I wanted. Lots of concrete at the bottom for the 4" drill pipe post. 

I think if I was needing another for more panels I might think of using 6" pipe. That gives room to grow the panels sizes in the future.

Do you need much elevation to get above snow?  I wanted 4 feet to clear any possible worst case snow fall.  If not for the snow I would build a near ground level rack myself.

Remember to protect it well against lightning strikes. The Midnite SPD's are excellent when coupled with a good grounding (earthing)  system.
Just because something has been done and has not failed, doesn’t mean it is good design.


Offline ChugiakTinkerer

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Re: OFF GRID POWER; various thoughts on...
« Reply #1511 on: February 15, 2021, 06:10:39 PM »
Keeping clear of snow is my only need for clearance.  Unless I need to worry about a moose scraping his antlers on it.

A ground mount may be the trick.  But that will still need to be anchored to the ground in some fashion.

My location is 62.4 degrees north latitude.  My initial thought was to mount with that angle of tilt from horizontal.  According to the PVWatts calculator I can squeeze out an extra 5% of output by keeping the panels at 45 degree tilt in the summer and 90 degrees in the winter.  That has the added bonus of keeping snow from accumulating on the array.  Changing the tilt angle twice a year would be no big deal.

I've been playing with the PVWatts to see how beneficial it would be to increase the panel size.  There's a big return going from 1.3 kW to 1.54 kW, it drops generator usage by tens of hours each year.  That assumes of course that I have accurately predicted what our occupancy and power load will be.  So maybe it's a phantom, but it certainly appears that paying for more panel area/output up front is a lot cheaper than paying for fuel and oil to run the generator year after year.

Also looking at bifacial panels.  With such high albedo for half the year it seems like a no-brainer.

My cabin build thread: Alaskan remote 16x28 1.5 story

Offline Dave Sparks

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Re: OFF GRID POWER; various thoughts on...
« Reply #1512 on: March 04, 2021, 06:56:11 AM »
Been pretty busy from the wildfires last year. I may have missed a few happy hours here...... Hey Don!

The history of bifacial is while they are beautiful and make sense, they are prone to leaking water in the back as the seals are small to let the light in. If you buy them, make sure you can get warranty. You may need it!

Below is a link to what I use to monitor clients and make adjustments anywhere there is cell or internet. It sends me alarms/warnings if I want them.

https://photos.google.com/photo/AF1QipMAjVuFzZ3vtUp5neK25EyEO5FJa-0Cx211cYXC
"we go where the power lines don't"

Offline ChugiakTinkerer

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Re: OFF GRID POWER; various thoughts on...
« Reply #1513 on: March 04, 2021, 05:54:00 PM »
Been pretty busy from the wildfires last year. I may have missed a few happy hours here...... Hey Don!

The history of bifacial is while they are beautiful and make sense, they are prone to leaking water in the back as the seals are small to let the light in. If you buy them, make sure you can get warranty. You may need it!

Below is a link to what I use to monitor clients and make adjustments anywhere there is cell or internet. It sends me alarms/warnings if I want them.

https://photos.google.com/photo/AF1QipMAjVuFzZ3vtUp5neK25EyEO5FJa-0Cx211cYXC

Thanks Dave, good to know.

I put my 50% down yesterday, for a 24V system with four Canadian Solar 375W bifacial panels.  I'll be sure to monitor the seals and hang on tight to my warranty paperwork.
My cabin build thread: Alaskan remote 16x28 1.5 story


Offline MountainDon

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Just because something has been done and has not failed, doesn’t mean it is good design.

Offline Dave Sparks

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Re: OFF GRID POWER; various thoughts on...
« Reply #1515 on: March 06, 2021, 06:38:07 AM »
Gives me an error, 404.....

I may have not turned the sharing on. Try this one.

https://photos.app.goo.gl/f3xJfJqQ4d6zEuKV9
"we go where the power lines don't"

Offline MountainDon

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Re: OFF GRID POWER; various thoughts on...
« Reply #1516 on: March 06, 2021, 02:36:25 PM »
That worked.   Cool tech.  [cool]
Just because something has been done and has not failed, doesn’t mean it is good design.


Offline MountainDon

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Re: OFF GRID POWER; various thoughts on...
« Reply #1517 on: March 06, 2021, 02:37:47 PM »
Hoping for a good spring and summer, but we haven't had enough moisture to really make that a certainty. 
Just because something has been done and has not failed, doesn’t mean it is good design.

Offline Dave Sparks

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Re: OFF GRID POWER; various thoughts on...
« Reply #1518 on: March 07, 2021, 08:10:04 AM »
I know what you mean Don. Snow pack is 2/3 normal and even worse in the southern sierra. Below is a link to some pix I am getting from the utility camera's that are all new this last year. I think they know fire season is going to get worse before it gets better. The state is doing a better job in dealing with forestry issues. In the past it was do nothing and blame it all on climate change. The politics do not matter when half of the state is on fire. The towers in the pix are what I monitor/adjust in the previous monitor link. Hope you and Kathy are doing well ! We got shot with moderna on friday. Crossing fingers ;)

https://photos.app.goo.gl/5cb1FzLkAa22UGpB8
"we go where the power lines don't"

Offline Dave Sparks

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Re: OFF GRID POWER; various thoughts on...
« Reply #1519 on: March 08, 2021, 10:25:26 AM »
I think it is too late for that :)

[moderator note: this comment was in response to a deleted spam post]
« Last Edit: April 01, 2021, 03:21:06 AM by John Raabe »
"we go where the power lines don't"


Offline MountainDon

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Re: OFF GRID POWER; various thoughts on...
« Reply #1520 on: March 08, 2021, 05:31:26 PM »
I would guess that [spammer name removed] is a potential spammer.

[moderator note: this comment was in response to a deleted spam post]
« Last Edit: April 01, 2021, 03:21:50 AM by John Raabe »
Just because something has been done and has not failed, doesn’t mean it is good design.

Offline NathanS

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Re: OFF GRID POWER; various thoughts on...
« Reply #1521 on: April 15, 2021, 08:27:36 AM »
Well I don't need off grid power, but for some reason I punched in my info on tesla's website. I can't believe this price.. unfortunately they don't serve my area.

After tax credits $4k installed?!?! I would have thought if I bought materials and did everything myself, then whatever professional requirements for the grid/battery tie safety it would have been closer to 20-25k.

People will spend more than $4k on just a generator!



Offline ChugiakTinkerer

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Re: OFF GRID POWER; various thoughts on...
« Reply #1522 on: April 21, 2021, 05:46:19 AM »
My off-grid power setup is running about 20k and that is with me doing all the installation.  The solar panels and battery bank aren't cheap, but they do bring the cost per kWh down considerably compared to using just the generator.  Granted, I'm amortizing the costs over thirty years and I may not even be alive long enough to see all those savings.

The Tesla estimate hides a lot of details in that little asterisk.  Anyone who would buy a system based on that estimate is deserving of all the surprises they get.
My cabin build thread: Alaskan remote 16x28 1.5 story

Online Redoverfarm

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Re: OFF GRID POWER; various thoughts on...
« Reply #1523 on: April 21, 2021, 06:23:58 AM »
A question for those who have roof mounted solar panels.  Do you have metal or shingles?  If metal what kind of mounting rails did you use?  Ease of installation? 

Offline MountainDon

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Re: OFF GRID POWER; various thoughts on...
« Reply #1524 on: April 21, 2021, 01:40:59 PM »
We did pole mount. I have seen metal roofs with panels but have no idea what most have used. There is one guy near us with a standing seam roof and he used some special mounts that secure to the standing seams. Your roof is the typical panels that overlap, like ours,  IIRC.
Just because something has been done and has not failed, doesn’t mean it is good design.


 

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