Solar home work 4 all

[Rgearhead]

Hi my solar friends.. i was in a solar black hole to... then i found out just one weak link and your system is nuttered..one blogger who is a RVer helped a lot, be sure their is no weak links,Bob is a retired electrical engineer who traves(lives) in his RV with his wife and has no generator..soo here is some home work if you will, google handy man bob blog.... or something like RVer handy man bob.. and when you find him READ ALL HIS BLOGS,, he figured out small systems, makes them work,, had to it's what they live on, pay attention to when he speaks wire size and how a solar charger controler should work, most solar chargers might only be bringing a battery bank up to 70% but showing full... was a real eye opener 4 me .. if you check it out please report back,k

[condomain]

I hope this is the right blog

http://handybobsolar.wordpress.com/the- ... -puzzle-2/

[myheirloomseeds]

I'm visiting and reading the blog now. Experienced RV users have excellent advice for running and maintaining battery banks as their systems often times receive a tremendous amount of depth of discharges (DOD) with their prospective battery usage. You should also check-out Boaters as well as they too need to have dependable battery banks in place since often times they out at sea.

BTW wire sizing is critical and must be done properly for battery banks. If done incorrectly you will have extremely voltage drops which can also lead to battery shortages and in some cases overheating of wire/cables which can be a fire hazard. You don't want a fire around a battery bank

Thanks, I truly believe that everyone should have some type of alternative power source.

Troy B

[Everyman]

Excellent seat of the pants insight based on real world experience. The only comment I have is 14.8 volt charging recommendation. This scheme is very common, widely used and will be a success; but if you and your batteries are in a warm climate you'll need a cooling fan on them and lots of distilled water, checked daily to maintain their electrolyte level. Also the batteries will mist acid (H2SO4 forms a aerosol easily) at an significantly increased rate and that mist will collect on anything in the same compartment. He must stay in temperate climes so he is unaware of this problem.

His experience with MPPT controllers is similar to my own.

[myheirloomseeds]

His experience with MPPT controllers is similar to my own.

Yes, those of us in the real world agree (well some of us) that MPPT controllers are best used on PV system with above average wattage. Like you Everyman, I believe you can either go with the PWM controller and place the saving in additional panel(s) and of course higher grade of wiring or keep the savings in your pockets verses buying a MPPT controller.

Man but those Magnum inverters will put a hole in your pocket!

[Everyman]

His experience with MPPT controllers is similar to my own.

Yes, those of us in the real world agree (well some of us) that MPPT controllers are best used on PV system with above average wattage. Like you Everyman, I believe you can either go with the PWM controller and place the saving in additional panel(s) and of course higher grade of wiring or keep the savings in your pockets verses buying a MPPT controller.

Man but those Magnum inverters will put a hole in your pocket!

I agree and I can't figure out what advantages they have other than the company claiming they are "premium" inverters.

[grizz]

Rgearhead,
Many thanks for posting that excellent article.

I found the most interesting discussion on wire size: This is exactly where I ran into a brick wall on my well pump project planning. Distance & wire size between panel, controller & battery is a huge deal.

I need to fix this on my fencer project where my panels are too far away from the controller. The fencer project works A-OK, but I'm sure it will work a lot better by fixing the wire size for the distance covered. Details on this HORROR story here where I have a 30% loss in power between the panels & charge controller because of inadequate wiring.
https://docs.google.com/document/d/1jQO ... 5ajcqe2uqx

WIRING: Resistance or impedance is the enemy. You have to overcome it and get the power to the batteries, not just to the output terminals on your charge controller. The system in my rig is efficient because I wired it with six gauge wire, for a total distance of only 12 ft from panels to controller. I ran #4 from the controller to the batteries. I spent about $30 for this wire and gained about $120 worth of added power when looking at what 6% of what my panels cost, which is about what I gained when going from 25ft of poorly routed #8 wire to 12ft of #6 wire. Big wire is even more cost efficient when you are looking at the difference in cost for a new installation. If your controller is located very close to the batteries like it needs to be, it will regulate the voltage to the batteries so they get what they need. You can run smaller wires from the panels to the controller than you run from there to the batteries, but make sure you can get nearly 16 volts minimum to the controller by looking at a voltage drop table. Big wire is cheap compared to the cost of panels, so err on the big side. You can either run big wire or install multiple smaller runs and split the panels up into several feeds. DO NOT tie the wires together at both ends. One wire will always have less resistance & carry more of the load. Find a voltage drop chart and limit your loss from the roof to the batteries to 3%. This way you can ignore the drop in the wires on the roof. You will find that voltage drop is directly proportional to the number of amps (higher amps equals more voltage drop), which is why you should wire for the number of panels you might need and not use the minimum size for the panels you initially buy. Use BIG wire, at least #8 for two panels and, and #6 for three panels and that is only for runs under 20 ft. I have installed a lot of #4 cable and wish I had it in my own rig.

From the controller to the batteries the wire size is critical. The bigger the better. If you cannot design for less than a 1% drop due to the length of run, it is possible with better controllers (Morningstar Tristar & Prostar, plus a few others) to use remote voltage sensing and the controller will boost the voltage going out, so that the correct voltage reaches the batteries. Do not be tempted to use this as a way of installing smaller wires. Voltage drop in the run between the controller and the batteries equals wattage loss in charging. Fewer watts come out of the end of the wire than go in when the voltage drops. This means that using smaller wires here will cost you watts charging every day forever. This is a foolish place to save a few dollars.

A word on the stranded wire debate: Yes, you should use stranded wire because it is better for DC power. However, the difference between stranded building wire and finely stranded automotive or welding cable is teeny, tiny electrically, so don’t obsess about it. The finely stranded stuff is easier to work with, but the main thing to worry about is a UV rated shield on the roof, protection against damage when routing through the rig and the price. Buy what you can find at the right price and what you can deal with mechanically. There is nothing wrong with running big, stiff wires and then splicing short, flexible leads on the ends to make it possible to connect to terminals. The big wire is there to limit voltage drop, not to carry amps. You are not going to load it enough for the splices to get hot and fail. http://handybobsolar.wordpress.com/the- ... -puzzle-2/

Here is a very nice wiring size calculator to help in planning wire size to provide less than a 2% loss in our projects:
http://www.calculator.net/voltage-drop- ... &x=65&y=13

Also his discussion about volts being measured AT the battery being so important, because of losses in the wiring between the battery & the controller. He also pointed out that the the battery must be maintained at 14.4+ volts for at least 2 hours to get a "full charge" before dropping down to trickle charge. He prefers 14.8 volts or even 15.2 volts for more for that 2 hour period. Also fascinating how useless "most" battery chargers are to get a "full charge" before dropping down to trickle charge. He states that most battery chargers won't hold 14.4 or more volts long enough to get a full charge. A lot of food for thought here.

IMO,
This was a long article but well worth taking the time to read. He did say that he would use a MPPT controller when he converts his house to solar, but would be using high voltage panels to get the most out of MPPT.

Grizz

[grizz]

Rgearhead,

You are my hero ! Here are the details on HandyBob's favorite battery monitor, the Trimetric. I NEED THIS ON MY SYSTEM !

The newer Tri-metric 2020 and 2025 meters (bogartengineering.com) are even better, lower priced, easier to wire and program and that is what we now have. (I have installed scores of them and everyone who has one loves it). The instructions include an explanation of charger settings that agrees with what I say above. The percent of charge readout is all most folks ever need to look at, except for occasionally checking volts & amps just to watch for changes in system performance. It is like keeping an eye on your blood pressure.

Video:
http://www.youtube.com/watch?v=aJtewad5m3g

Tech Specs & SolarBlvd price:
http://www.solarblvd.com/p1161/Bogart-E ... _info.html

Setting it up for our system:
http://www.bogartengineering.com/sites/ ... er2005.pdf

Add-Ons explained & video explains the newer 2025A & 2025RV
http://www.altestore.com/store/Meters-C ... itor/p254/

HandyBob likes the Morningstar Tristar controller. Specs:

I refused to work on it unless I could replace the controller with a properly rated Morningstar Tristar with a temperature sensor and locate it in the next compartment over with the inverter. After rewiring with #4 cables, fixing the multiple shading problems (Panels = 720 Watts) on the roof, and doing some reprogramming and education concerning his Link meter, this guy now successfully runs everything he wants, including a the 38”TV and the freezer, without running the generator. The generator is only needed after a couple of cloudy days.

http://www.solarblvd.com/p95/Morningsta ... _info.html
Manual explains exactly why he likes it
http://www.morningstarcorp.com/en/suppo ... .04.EN.pdf
Adjustable battery charge voltage & auto-equalize via dip switches.

Question for the experts here: Is Trimetric the best battery monitor? Is there a better choice?

Grizz

[mmpaints]

Hey guys, excellent discussion and this will be a great resource for anyone looking at solar. This has now become a "sticky" so it's easy to find. Well done!

[Rgearhead]

your all welcome, i was lost 2 years ago , watching vid after vid on you tube of people CLAIMING' I'm set , look at all i can power off my battery's, and how long MY System can run things,ect,ect...they start with 100% fresh charged batteries , ya sure it works, right then and now, but no one ever spoke how long and what it takes to bring their batteries back up to full charge and go again..and i fell into that group to.. till i put some time into seeing if the little solar panels i had could bring the batteries back 100%, pfft' not even close. so i was bummed....till i stumbled on to handy bobs blog...then i scraped all the harbor freight solar crap and this spring I'm going handy bobs way....I now have 640 watts of REAL solar panels and bought 6- 6 VOLT Deep cycle batteries that are 230 amp hours each, but seeing as I'm going 12 volt battery bank system wired series parallel will give me a total of 690 amp hours storage total and i have 2 inverters, not the best brand, Aims, 1 is 2000 watt pure the other is 3000watts mod..i have bought 200 feet of 6 gage wire just to go from solar panels to charge controller, about a 70' run, i so i had to go over size..i just need to order my tri star and wait for the weather to break, then I'm going full throttle on this, i will report back with pictures and let you know how it goes,I'm sure it will now work as i want-need..
I hope others trying also report back ..We can save a lot of people a LOT of money doing it once n doing it right...
thanks Bob..

[Everyman]

Something to keep in mind about battery condition meters.
Battery condition meters are fun and somewhat useful. I’ve seen and use both Link and Tri-metric meters. They both have the same shortcoming when fulfilling their claim to be Battery Fuel or Condition meters. But they are reliable volt and amp meters.
They are basically electrical bookkeeping devices. By this I mean they measure and tally the amps into and out of the battery and from that infer its condition. This sounds straight forward enough but you have to remember that the battery is a chemical system which is subject to other perturbations unique to the chemical domain. The most notable of these is called by Peukert's exponent. This is a variable that is applied to batteries when they are at different levels of load. When you use these accounting meters you preset this exponent to match the size of your battery bank. This is a somewhat less than accurate approach (but the only really practical method) because the exponent changes with several battery variables.

This results in errors in the meter’s accounting system. These errors accumulate each time the battery is cycled; e.g. sees a high current discharge or charge. In active systems these accumulated errors quickly become so large the “battery condition” or “Fuel Gauge” function becomes meaningless and the meter must be reset.

Various meter makers deal with this problem in different ways. I think both Link and Tri-metric now use the same method. When the batteries are fully charge the meter automatically resets. This is probably the best approach but it has one problem. In an active pv system the batteries are very seldom fully recharged. It takes hours to do the final saturation on a battery bank and you will typically draw power with a high current device from the bank and upset the process, before that can be accomplished. Furthermore since the final charging stage adds only something like 10% of the total charge, but takes hours, folks just don’t bother with it when using a generator. So you seldom get an automatic reset of the system.

In every system I’ve seen with these the user eventually gives up on the fuel gauge function and simply sets the meter to alternate between reading Amps and Volts. They use the computer between their ears to evaluate battery condition. E.g. If the volts read 14.4 and the amps read say +5 then the batts are nearly full. If the batts read 12.3 volts and the amps read -35 it time to shed some loads. This organic real time training is the best way to intuitively understand an off grid system.
There is no reason to not buy these meters because even when they are only used as volt-amp meters they are cheaper than dedicated volt-amp meters. Just don’t get your hopes up on the fuel gauge function.

[myheirloomseeds]

I now have 640 watts of REAL solar panels and bought 6- 6 VOLT Deep cycle batteries that are 230 amp hours each, but seeing as I'm going 12 volt battery bank system wired series parallel will give me a total of 690 amp hours storage total and i have 2 inverters, not the best brand, Aims, 1 is 2000 watt pure the other is 3000watts mod..i have bought 200 feet of 6 gage wire just to go from solar panels to charge controller, about a 70' run, i so i had to go over size..i just need to order my tri star and wait for the weather to break, then I'm going full throttle on this, i will report back with pictures and let you know how it goes,I'm sure it will now work as i want-need..
I hope others trying also report back ..We can save a lot of people a LOT of money doing it once n doing it right...
thanks Bob..

Reearhead..I would re-check your wire sizing. Based on the information you presented above your 640w of PV at a 70' run (distance from the PV's to the charge controller) you're a little over the recommended 3% voltage drop. You're approximately at 3.014% I mean right at the border and NOT over sizing in terms of using 6 gauge. I know it's costly (but well worth it) to get the 4 gauge if you're going to do a 70' run. At least this is what I would do.

For others here is a nice wire sizing calculator: http://www.powerstream.com/Wire_Size.htm

In terms of the question that was asked from Grizz...The Tri-metric meters are in the top of the line Battery meters. However, like Everyman said they don't factor in Peukert's exponent, therefore YOU must make the necessary adjustments and calculations concerning your battery bank. Remember these are only tools for us to gauge our equipment/battery banks. My main concern would be current voltage, Amps in/out and I would not be all to concern with keeping LONG history of ampere hours out so I would be resetting my meter to suit my needs. I would using the meter to see if there are weak cells in my battery bank etc and that can be determined by the state of charging and maintaining that charge.

Let's keep the information flowing because for sure many are benefiting from it. Higher wires/cables sizes, inverters close as possible to the battery bank as possible, fuse the heck out of your system, battery bank maintenance and we all will have an efficiently ran powerhouse for years!

[grizz]

Last Update = 3/2/13 - lower panel prices
Since this thread is a sticky, I'll use this message to post VALUABLE references, and edit this message to add new references as required.

Best Prices for Solar Panels
If anyone finds better prices elsewhere, send me a PM and I'll add it here
http://www.solarblvd.com/Solar-Panels-& ... index.html
32 Cents per Watt here
http://campaign.r20.constantcontact.com/render?llr=cgx9b8cab&v=0015_lm2NH4ZFI6Q_JNPsWQFU1gDZZffbEpd-SV8sRp6LClMmcYVyMCe7fqN60PflK6-ITNwYCPaMyk25rsv4gb7U6QKW8G7WmIGBWWTFTbIjQ%3D

Formulas to help for Success
Ohm's Law:
Amps = Volts / Ohms
Volts = Amps * Ohms
Ohms = Volts / Amps
Power Formulas:
* Watts = Volts * Amps
* Amps = Watts/Volts
* Volts = Watts/Amps
* Watts/Inverter Efficiency = Watts drawn from battery
* Inverter Amps Per Hr from battery: Watts load on inverter divided by input volts (12) = the DC amp consumption per hour from a battery. (plus expected efficiency loss)
* Inverter Run Time in Hours: (Total Amps in Batteries/12) / total Amps Load on Inverter + ½ Amp (for inverter itself)
* MPPT Controller Pwr Boost: Solar Imp(amps) * Vmp(volts) / Battery(Volts)=Battery Boost (amps)
* Wire Voltage Loss Calculator: Loss should be less than 3%
http://www.calculator.net/voltage-drop-calculator.html?material=copper&wiresize=5.211&voltage=12&phase=dc&noofconductor=4&distance=60&distanceunit=feet&amperes=15&x=60&y=12

[b]Home Made Ground Mounts[/b]
http://www.youtube.com/watch?v=0aQSrIrqZRg
Ground mount for a 20Kwh solar project:
http://www.youtube.com/watch?v=d7bga5hEUQ8
Photos of my home made ground mounts:
https://docs.google.com/document/d/1jQO ... FoFg/edit#
DIY Solar from Home Power Magazine

http://www.homepower.com/search/content/diy%20solar

Home Power Magazine:
Displays the most recent magazine to read. Also contains all past articles. Use the search function to find valuable articles from past issues:
FEATURED ARTICLES:
http://www.homepower.com/solar-electric ... stallation
http://www.homepower.com/search/content/wiring%20loss


To be continued, send me a PM to add your favorites here,
Grizz

[Everyman]

I have a couple of really useful Excel spreadsheets. But I can't figure out where to put them online so I can link them back to here so others can download them. Anyone have any Ideas?

[grizz]

I have a couple of really useful Excel spreadsheets. But I can't figure out where to put them online so I can link them back to here so others can download them. Anyone have any Ideas?

EveryMan,

1) Go to Google:
https://www.google.com/
2) Sign up Google Drive, at the top menu
Google drive is free, unless you start hogging up 5 gigs of space, then they have a small monthly charge.

Google Drive allows you to publish documents, spreadsheets, drawings, & presentations to the internet with a link. You can also just share with a few friends by including their email address in your SHARE controls.

My Solar Fencer Doc was created with Google Drive:
https://docs.google.com/document/d/1jQO ... FoFg/edit#
My Septic Field Rejuvenation Project was done in Google Drive:
https://docs.google.com/document/d/1HL- ... l8634t5wn3

I also use the fantastic Email from Google, called Gmail. Gmail directly links to a WEALTH of free google applications including Drive. You can get started with Gmail here:
https://www.google.com/

I also love the Google Chrome Browser. The BEST & FASTEST Browser ever:
https://www.google.com/intl/en/chrome/b ... _medium=ha

Best to you,
Grizz