Author Topic: Home Solar Power ??  (Read 15833 times)

alfsauve

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Re: Home Solar Power ??
« Reply #70 on: November 08, 2022, 11:32:50 AM »
Here's the whole sorted story in one post.

What I did over Fall Break
Or
My Solar Emergency System


Synopsis
•   Wanted an emergency power backup system primarily for the freezer to protect the turkey, hog and deer meat.
•   Went with Gel batteries, 2 @ 100Ah, because they will not be deep cycled often enough to warrant the cost of WiFeP.
•   Installed two 100W mono panels to keep the batteries charged and to cover some light usage.
•   Utilized a 1,000W Renogy pure sine wave inverter.
•   Did a test run with the Freezer running off the batteries for 6 hours with no problems and meter still said 30hrs left.
•   Have it on a portable platform in my work room where it will run the other battery chargers and the occasional use of the belt sander and grinder.
•   Cost before rebate, $1,430.  After rebate, 1001.22   

I research and planned a solar system trying to save money on my electric bill.  As many have discovered, depending on the application and the solar exposure it was a no win for my situation.  After much discussion with the CFO and co-CEO of our family we finally put a dollar amount on the remaining benefits of solar. 

     Environmental bragging rights   $5
     Tinkering/Experimenting      $250
     Emergency Backup         $1,000

So there’s my budget.  $1,255. Ah but wait.  There’s a 30% discount if it’s a “solar” system.  C-o-o-l!

The primary usage during a power outage would be to save the frozen foods in the freezer and refrigerator.  Analysis shows the new freezer draws 500Wh each day.  Obviously during prolonged outage we’d minimize the times we open the doors and turn the temperature up a little. Given that this is not a daily, off-grid usage but strictly for power outages, and maybe occasional portable usage, Gel cells were selected to save money. Deep cycles, space and weight are not a primary concern. The house and lot don’t have a good southern exposure but two typical PV cells can be mounted on an odd, south facing roof extension by the garage, giving 4-5 hours of sun a day.  As an emergency system designed only to provide short term coverage, the cells should be adequate to keep the batteries topped off.  If, per chance there is an extended outage then the cells would help stretch the power coverage. I was able by using Home Depot for some Renogy items, and Amazon for the batteries and accessories. The out-of-pocket, including shipping and taxes is $1,430.  After rebate that’ll come to$1,001.  Well within budget and with two 100AH batteries and two 100W solar cells for redundancy.

There’s my initial concept diagram.
 
The initial drawing was for a 2,000W inverter, but after analyzing the need further I’ve down sized it to a 1,000W model.  Also added a fuse to feed the 12V fuse block.  Since I’m a ham radio operator and all my radios operate off 12V I thought having a 12V distro would be handy, for participating in portable operations such as ARRL Field Day.  Here’s the list of materials ordered.  to which was added a 4AWG crimper and ome 3/8”– 4AWG lugs:

2ea   Weize Gel 100Ah Batteries
1ea   Renogy 1,000W Inverter
1ea   Renogy 500A battery meter
2ea   Renogy 100W Mono panel
1ea   Renogy 30A PWM Charge Controller
1ea   Renogy PV panel Accessory kit
1ea   A/C Battery Charger
3ea   ANL Fuse Blocks w/ 100A fuses
2ea   30A ANL fuse
2ea   20A ANL fuse
1ea   Fuse block with 6 blade fuse protected circuits
4pr   5/16”-4AWG connector pack
1ea   Cable Crimping tool 8AWG-1/0
3ea   Black/Red Pair 1’ 4AWG cables with lugs
1ea   Plywood DIY enclosure
2ea   Mini Tie-down straps
5ft   10AWG wire with 5/16” lugs
100ft   12AWG 12/2 Solar extension cord.
6pr   Solar MC4 Connectors
1ea   14, 12, 10AWG crimper
1ea   8AWG-0/0 crimper
4pr   3/8”-4AWG lugs

The box design initially had the component on a vertical panel extending upward from the battery box.   I realized this would somewhat unwieldy trying to put it into a vehicle for portable operation.  I then made a two shelf design.

Two by two feet might be a little hard to get into the back seat of a vehicle and even into some boots/trunks, so  I experimented  with downsizing it to 24”w x 16”d x 16”h.  This makes it more portabl.  I built a 9” tall stand (table) to bring the box up off the floor and I just happened to have a flat dolly of perfect dimension to hold the box should I want to move it around.

There’s a picture of the components while I plan the layout.  I could have gone with min-ANL fuse blocks to protect the PV Charge Controller and the 12V distro block but the ANL fuse blocks came in a package of 3.
 
So the final design the cabinet size is 16”h x 23”w.  You can see the final assembly of the electronics shelf in the background.
 
I hate cutting out keyholes so there are only three in the bottom which will allow me to strap up to three batteries down.  Below is the final assembly, and yes there are handhold for lifting, though at 150# one’s not likely to do it by oneself.  The electronics shelf is NOT attached but sits on the side rails.  This allows easy access to the batteries and prevents any attempt to lift the box by the top shelf.
 
 

And how’s it working?  First I topped off the new batteries with the A/C Charger.  Then ran the Freezer for 6 hours off the Inverter.  I was surprise, don’t know why but I was, by how quiet it was.  It was 100W off a 1,000W inverter so the fans didn’t even come on.  I guess I was expecting some grunting and groaning of which there was none.  After six hours the meter said I still had over 30 hours left.  I know it’s an educated guess by the meter and I also know that this time will vary by ambient temperature.
My next experiment was to plug in the 40V A/C charger for my Ryobi power tools and charge a nearly dead 6Ah battery.  It took more power than I would have guess but of course was handled easily by the setup.  Then, due to whatever demons possessed me, I plugged in my air compressor, mainly because it was sitting right next to the rig.  Shocked I was to look over and see the meter indicate a 98A draw.  That exceeds the nominal capacity of the Inverter.  (Shades of Star Trek ran through my mind as I could hear Scotty saying, “we’re at 110%, Captain.”)  I only let it run for about 30 seconds when I realized that as the pressure in the air tank increase the motor would have to work harder and draw more current.  Then, in hindsight, I checked the specs on the compressor…. (wait for it)…. 1,440W!
The panels finally came in and I mounted them on my little roof.  Ran 12AWG, extension cables to the work room through the roof top vent.  Of course during my first real day of operation it was overcast, but now that there’s full sunlight we’re charging quite well.  The thing about winter is that while the sun is lower on the horizon and there are trees in the way, those trees have all lost their leaves so the effect is minimal on the cells.
 
Because I didn’t have an initial intent of adding cells to this system, I mounted as I did, but as soon as I was finished and put the ladder away the CFO says, “We need more solar panels.”  Two mistakes were made.  First not putting the panels closer together which would have allowed for two more cells on the same row.  And secondly, I have the cables/junction on top.  If two more cells are added below the existing two it would be easier if all the cables were in closer proximity.  This is easily fixed in the future.


Lessons learned

  • The Renogy Meter was not designed to be surface mounted.  I had to fashion a mount out of a plastic utility box for it.
  • The Renogy Charger controller does come with a surface mount, but it needed a slight modification to be practical.  I cut away the individual cable slots on the box so the controller could be more easily lifted out of the mount for securing the cables.
  • Having a real crimper designed for the application is a necessity.  I could never have crimped the 4AWG lugs with my small pliers-type crimper and they wouldn’t have been very secure if I did.  I also destroyed my first MC4 connector and the second connector pulled loose with the first tug.  The two crimpers I purchased were a very good investment and I wish I had bought them earlier for other projects.
  • Plan for future expansion even if you don’t think you’ll need it.  Mount the panels as if you’re going to add more later and allow room on the electronics area for adding other devices or upgrades to a bigger inverter or charger.
  • Though I knew the dimensions, the various components were bigger than I had imagined, so leave extra space.
  • It is so eerily quiet when in operation.  I had expected at least a little humming, grunting or groaning.
    More panels and more uses will be added over time.  The outside security lights, the workroom lights, my ham radio station and other utility functions.


Will work for ammo
USAF MAC 437th MAW 1968-1972

Rastus

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Re: Home Solar Power ??
« Reply #71 on: May 07, 2024, 08:29:53 AM »
Things have gotten cheaper since the last post.  And the price of the equipment should fall from where it is because the tax credit in California is going bye-bye and lots of solar installation companies are, according to news reports, going out of business.  So I'm figuring that equipment suppliers will begin to drop prices.

One caveat I haven't caught until I've been studying solar is the open voltage potential on solar cells.  In essence, my 12V 100 watt panels (now $60 with tax delivered) have an open voltage of 25 volts.  When you add solar panels together they essentially (methinks) add up.  So 12 panels (1,200 watts) require a solar charger that can handle 300 volts of open voltage.  HOWEVER, if you buy say 200 watt panels they have an open voltage of ~36 volts and 1,200 watts (6 panels) would have an open voltage of only 216 volts which will result in a cheaper charger. 

Plus, and this is a biggie, the LiFEPO4 batteries costs has fallen 5 fold in a year.  A 12 Volt 100 ah battery was around $1,100 a year ago...now you can get them for $200 with a battery management system onboard.

There are basically two types of chargers.  There are the MMPT (Maximum Power Point Tracking) and PWM (Pulse Width Modulation) chargers.  The MMPT seems to reduce charging times by 10-15% due to it's efficiency. 

We start building a barn some time next month.  My wife needs electricity for a few lights, some hot water (propane instant on but needs a little current to operate) and we need to put a small air conditioner unit in the tack room to keep everything dry (lots of fog here in the Ozarks so 5000 BTU at say 600 watts max draw).  We are building at least 400-600 feet from a source of electricity so when I look at burying a line to the barn (hate those poles) the cost is pretty high...wire, trench, tying into existing system, etc.  Now looking at costs the solar appears to make sense to me and I'm going to install an independent solar source in the barn.  I haven't finished a design yet but on the high end $1,500 in panels, $1,500 in chargers/inverters, $1,000 in batteries, $1,500 install and $500 in misc. wires and mounting parts.  On an electric bill basis that puts us at a ~10 year payout....not considering the offset from not installing and tying in 300'+ of underground power lead. 

Necessity is the plea for every infringement of human freedom.
It is the argument of tyrants; it is the creed of slaves.
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alfsauve

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Re: Home Solar Power ??
« Reply #72 on: May 07, 2024, 08:50:53 AM »
Thank you Rastus for the update.  I was at the Georgia Out Doors Trader swap fest and gun show this weekend and some small dealer had 100AH LiFePo batteries for $150.  I thought it was a joke, but now I know that yes prices have fallen tremendously..

I might consider replacing the Gel cells for the weight savings. 

Don’t know if I mentioned it but I added 2 more solar cells.  Run each pair in series and then the two pairs in parallel.  Yes the open circuit voltage can get up there especially in the 30-50V cells. For that reason the NEA requires emergency cut off to protect first responders, but only on roof mounted cells.  If you run micro inverter mounted under the cells then no problem because they shut down when there’s now line voltage.  (Which is why they’re no good for emergency, power outage use.). But a big caveat to the NEA is that the cut off only has to ensure the voltage in the feed wires is less then 30V.  With my set up it never gets above ~25V so no cut off is needed.
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Big Frank

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Re: Home Solar Power ??
« Reply #73 on: May 08, 2024, 11:51:42 AM »
You forgot the most important one... the tax credit/ write offs.   Onky reason business  are doing it. They are saying its to be green, but thats bull shit.  Its about being able to wrote off the entire system.

How green is all the mining, manufacturing, and transportation that goes into making all that solar stuff? Not very, by my best guess. The truck exhaust for transportation of all the materials is gray or brown or black, but not green.
""It may be laid down as a primary position, and the basis of our system, that every Citizen who enjoys the protection of a free Government, owes not only a proportion of his property, but even his personal services to the defence of it, and consequently that the Citizens of America (with a few legal and official exceptions) from 18 to 50 Years of Age should be borne on the Militia Rolls, provided with uniform Arms, and so far accustomed to the use of them, that the Total strength of the Country might be called forth at a Short Notice on any very interesting Emergency." - George Washington. Letter to Alexander Hamilton, Friday, May 02, 1783

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Big Frank

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Re: Home Solar Power ??
« Reply #74 on: May 08, 2024, 12:26:23 PM »
On the DIY Solar forum someone wanted to how they could measure their sunlight, over time, at different locations around their house.  Got me to thinking.  I have an Ambient Weather station which is on-line (yes you can check out the weather at my house) and one of it's features is a Solar Radiation and UV index.  I never paid much attention to those readings, I mean if it's bright and sunny outside they're high.  Duh.  But then I thought I'd dig a little further and sure enough Ambient Weather keeps, at least the last 24hrs of readings on-line.  Now my weather station is located near my only south facing roof usable for solar cells.  Below are the graphs for the other day.   It is fall and the sun is getting lower on the horizon.  The trees are a real problem as you can tell.  If one wanted to go to the trouble one could put the weather station on a base plate and just set it in various places to get sun graphs.

I read something a couple years ago about putting solar panels on the west side of the roof instead of the south side. You wouldn't get much power in the morning, but in the afternoon when most people need more power, and when the power company may charge more for it like they do here in the summer, the solar panels would work better than if they were facing south. Also, if your solar panels make more electricity than you use, you may be able to sell the excess to the power company. I don't know if you can do that in all states, but you can here in Michigan. Or you could, when I read about it at one point.
""It may be laid down as a primary position, and the basis of our system, that every Citizen who enjoys the protection of a free Government, owes not only a proportion of his property, but even his personal services to the defence of it, and consequently that the Citizens of America (with a few legal and official exceptions) from 18 to 50 Years of Age should be borne on the Militia Rolls, provided with uniform Arms, and so far accustomed to the use of them, that the Total strength of the Country might be called forth at a Short Notice on any very interesting Emergency." - George Washington. Letter to Alexander Hamilton, Friday, May 02, 1783

THE RIGHT TO BUY WEAPONS IS THE RIGHT TO BE FREE - A. E. van Vogt, The Weapon Shops of Isher

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Re: Home Solar Power ??
« Reply #75 on: Today at 12:46:57 PM »

Rastus

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Re: Home Solar Power ??
« Reply #75 on: May 09, 2024, 07:39:46 AM »
I think a law back going to the Jimmy Carter debacle requires power companies buy your surplus electricity; if you want to sell some back.  That ability comes with caveats like transfer switches, etc. to protect lineman from have charged power lines from homes and businesses when working on the lines and the electric company must be notified of your intentions before you can tie into the system.

Next if your panels are fixed it's all about getting the most photons to hit the panels...and that's the middle of the day.  Pointing westward with fixed panels won't do the trick...someone's good idea...a government worker no doubt?  Pointing east or west is 25-30% less power capture.  And if they were thinking that is because of the cost of electricity....then you batteries are way too small because you should easily charge them up facing south and cover that westward high cost power time.   

In addition, after a little study I'm going to be putting 4 of my 100 watt solar panels into series to bulk them up to 48 volts from 12 volts.  So I'll have 4 in a "unit" then connect the units in parallel to feed 48 volts to the charger.  Those 4 panels will be capable of generating an open voltage of 97 volts...and I have a 250 volt rated charger.  So I can loose 2 units and still be covered.  48 volts means smaller wires and easier to install...and cheaper..but the higher open voltage rating pushes up the cost of the charger.

I have a 60 amp charger (Victron MPPT MC4 250V 60..$402 delivered).  Therefore, 12 volts limits me to 720 total watts worth of panels whereas 48 volts allows 2,880 watts worth of panels.  So, in my scenario I can have 7 units of 4 panels each generating 2,800 watts maximum.  I'll run 6 solar "units" and 2,400 watts for longevity to not stress the system.  Maybe leave a space to add that final unit as panel efficiency falls off over time.  And I just bought 2 more panels for $58 and a nickel each....and made in Thailand NOT China.
Necessity is the plea for every infringement of human freedom.
It is the argument of tyrants; it is the creed of slaves.
-William Pitt, British Prime-Minister (1759-1806)
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alfsauve

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Re: Home Solar Power ??
« Reply #76 on: May 09, 2024, 10:56:57 AM »
.....about putting solar panels on the west side of the roof instead of the south side.

I think I've seen some solar farms that favor the west side.  Especially, I'd think, if you're going directly to grid, then power in the afternoon would be more important.
The one farm I'm thinking of has the panels running E-W, tilted towards the west.  Trying to find a sat picture, but doesn't look like they've updated that section since the farm was installed.
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alfsauve

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Re: Home Solar Power ??
« Reply #77 on: May 09, 2024, 11:03:25 AM »
I think a law back going to the Jimmy Carter debacle requires power companies buy your surplus electricity; if you want to sell some back. 

Nope, there are no buy backs in GA.  Or I should say no new buy back programs.   We have about 14 electrical utilities in GA and the only thing they allow you to do connect to the grid and offset your cost by what you generate AND consume. You don't get paid for the excess.  The rest is a freebee.  GA Power (the only non co-op) did offer a buy back for the first 5,000 applicants.  That deal got snatched up in the first week about 4 years ago. 
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alfsauve

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Re: Home Solar Power ??
« Reply #78 on: May 09, 2024, 11:20:40 AM »
Using Renogy as a benchmark there's about a 50% reduction in the last 18months.

Still since I don't deep cycle and it's pretty stationary setup, $180/ea for 12V 100Ah GEL was my best choice.
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Rastus

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Re: Home Solar Power ??
« Reply #79 on: May 09, 2024, 03:48:10 PM »
50% reduction in price?  Back when you set yours up GEL was the best setup.  For the same price I like the LiFePO4 today. 

Home and business may be different.  I've some friends who generate electricity from surplus natural gas back to electric companies in 4 or 5 states and they get a check for it. 

Maybe if you are just looking to cover a shortfall in the afternoon and you don't have storage pointing to the west would help.  With storage that won't help me at all...the storage is the key.
Necessity is the plea for every infringement of human freedom.
It is the argument of tyrants; it is the creed of slaves.
-William Pitt, British Prime-Minister (1759-1806)
                                                                                                                               Avoid subjugation, join the NRA!

 

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