Working Thread for Solar Beginner Post/FAQ

BB.

Re: Working Thread for Solar Beginner Post/FAQ

Regarding Solar Books:

What's a Good Beginners Book?

From the above thread:

FL SUN wrote: »

This is a link to a PV textbook I find very informative. It was a requirement for the FL contractor's exam I took last month. It even has a very good interactive CD with a bunch of informative extras. A quick search on-line shows this book goes for about $75.00 USD everywhere.

Don't forget nothing compares to OJT when it comes to installation. It's always best to apply in the field what you've learned from a good textbook first.
http://www.powells.com/cgi-bin/bibli...26912879:75.00

TnAndy wrote: »

Rick,

Here a good "textbook" on solar......it actually IS a textbook for some solar courses, and is set up that way with practice questions at the end of each chapter, but it's also a good self guide as to the basics of components and how they mesh together to make a system. Worth the money, IMHO.

Solar Book Here

Some information on NEC and how it applies to solar power:

PV and the 2005 NEC -- Reference Document

And, of course, the NEC Code Book (current edition or version that is used by your locality).

-Bill

PS: Our host also has a Book they recommend (see update below 6/19/2017. -Bill B.):

Hey Bill,

Yes, that's a book that we used to sell. We stopped carrying it 2 or 3
years ago. The book was never updated since its last edition in 2008,
so I don't think I'd recommend it at this point. But if someone on the
forum is interested, the book is still available on Amazon. It was a
good book for the time it was published. Lots of good info. But we
don't recommend books anymore, and I'd be willing to bet that there
are some better and newer books available now.

https://www.amazon.com/dp/0937948179/ref=cm_sw_r_cp_dp_T2_vTbszb9374AMM

Rick

PPS: From another poster:

KeithWHare wrote: »

I recommend "Photovoltaics: Design and Installation Manual" from Solar Energy International. This does a pretty decent job of explaining everything except for battery banks.

Keith

PPPS: From another website, I saw this Boatowner's Illustrated Electrical Handbook recommended.

PPPPS:

rollandelliott wrote: »

according to wikipedia once it is adopted into law by a particular govt agency it becomes public knowledge

http://bulk.resource.org/codes.gov/ga_electric.pdf

is one link

there are many more specific to certain states/cities here

http://bulk.resource.org/codes.gov/

May 26th, 2013:

ChrisOlson wrote: »

I always recommend Hugh's recipe book
http://scoraigwind.com/axialplans/index.htm

It has the "plans" on how to build six different turbines. But Hugh also goes into the theory in explaining why the turbines are built the way they are, and it's written by a master that has spent most of his life working with wind power.

I don't know about the Otherpower book - I have only read excerpts of it and never the whole thing.
--
Chris

June 30th, 2013:

ChrisOlson wrote: »

Ed Lenz's website is probably the best resource for building a small microturbine. Ed has articles on there covering three-phase basics, along with several small windpower projects he has done, etc.
http://www.windstuffnow.com/main/

--
Chris

July 19th, 2013:

Panamretiree wrote: »

A good manual on boat electrics is: Boatowner's Mechanical and Electrical Manual: How to Maintain, Repair, and Improve Your Boat's Essential Systems by Nigel Calder. Goes through all issues that you can be confronted with, including solar, wind and hydro power. Has considerable information on grounding and bonding in a boat. Approximately $36.00 on Amazon.com.

Cheers

June 19th, 2014:

Both PNjunction and vtMaps have given a "thumbs up on":

PNjunction wrote: »

. you might want to take a look at this manual:

http://www.samlexamerica.com/product...il.aspx?pid=60

Covers FAR more than just the controller and goes into details about solar setups in general. Best I've ever seen, and devoid of hype. Highly recommended, ......

June 24th, 2014:

stephendv wrote: »

Energy Unlimited by Victron is a good introduction: http://www.victronenergy.com/upload/...limited-EN.pdf focussed on marine systems but 90% same for land based off-grid.

February 10th, 2015

Surfpath wrote: »

HX,
This was an excellent resource I came across that addresses your question [wire insulation/temperature requirements]:

http://www.cooperindustries.com/content/dam/public/bussmann/Electrical/Resources/solution-center/technical_library/BUS_Ele_Tech_Lib_Conductor_Ampacities.pdf

-Bill

BB.

Re: Working Thread for Solar Beginner Post/FAQ

Add from Stephendv (Oct 20, 2011; -Bill:

stephendv wrote: »

... Victron has authored a great paper that covers some interesting material on charging forklift batts: http://www.victronenergy.com/upload/documents/Book-EN-EnergyUnlimited.pdf

From Mike90045,

A nice 54 page book on batteries--even includes a Battery 101 primer (series/parallel connections, etc.): (see attachment at bottom of post)

mike90045 wrote: »

Only if your battery stays below 70% charged for more than 24 hours. The lead sulphate crystals will harden, and not dissolve during discharge. This is called sulphation.

Say you loose 1% capacity each episode, and one episode a week. In a year, you have 50% degradation of your battery. That's what insufficient charging gets you.

See attached battery file for in depth explanation.

Sulfation - Formation of lead sulfate crystals on the plates of a lead-acid
battery.

Added 3/5/2012: Here is a nice thread on why I/we suggest not paralleling batteries if it can be avoided:

Series rule of thumb

Toddlingham

Re: Working Thread for Solar Beginner Post/FAQ

I see your point. I've dealt with quite a few on demand heaters and they are more efficient ( unless there is always someone home constantly using hot water ) . Even the nicest ones have some drawbacks though. They are picky about clean sine wave power. They won't turn on until the volume passing through them is quite high ( long scrawny pipes to an upstairs faucet may impede flow enough to prevent heater from turning on. ) They really do take massive gas flow. we've had to upsize pipe and install two stage regulators to get sufficient gas to tankless heaters. They ended up costing a lot more to install than we'd hoped and weren't cheap to start with. However, the power consumption/gas consumption has dropped. They are especially well suited for supplementing solar water heaters since solar heaters aren't always starting off at the same temp. A tanked heater after the solar is a big waste as preheated water sits in it cooling and being reheated by your wallet continuosly.

Toddlingham

Re: Working Thread for Solar Beginner Post/FAQ

Keeping batteries well maintained pays. I have yet to see success in restoring batteries once deteriorated. De-sulfators are reputed to help if used frequently to head off sulfation pre-emptively but not for bringing back the dead. Anyone out there having success? Battery manufacturers sure pay better for used batteries than scrap prices.

BB.

Re: Working Thread for Solar Beginner Post/FAQ

Some fine testing from John about 1/2 and 3/4 copper water pipe used as bus/jumpers for battery banks:

john p wrote: »

IM not wanting to get into another discussion on bus bars again but just reposting the post from a long time ago and the results for FARMERJOHNAZ to see if this answers his question..
It shows the very tiny losses you get from using cheap copper tube available from any hardware store.. you just hammer or put in vice the ends of the short lengths of tubing to flatten them then just drill a suitable sized hole each end..

Here is the results of resistance testing and mechanical destruction testing of lugs on copper wires as used in battery interconnects and similar usage.

A total of 10 lengths of copper water pipe was purchased from hardware and plumbing supply stores. The 2 sizes purchased had inside diameters or 1/2 "(12.5mm) and 3/4" (19mm) thickness ranged from 1.25mm to 2mm. All pipe lengths were 10ft (3050mm)

Each size and thickness of pipe was purchased from a different supplier
All measurements were carried out on a calibrated desk multimeter.With a accuracy of+ or - .02%

1.1/2 pipe 1.25mm =.0012 ohms

2.1/2 pipe 1.25mm =.0013 ohms

3.1/2 pipe 2mm soft = .0008

4.1/2 pipe 2mm hard = .0009

5.3/4 pipe 1.5mm = .00065

6.3/4 pipe 1.5mm = .00061

7.3/4 pipe 2mm soft= .00042

8.3/4 pipe 2mm soft = .00041

9.3/4 pipe 2.2 hard = .00040

10.3/4 pipe 2.1 hard = .00039

As noted the resistance was given for 10ft lengths of pipe . If we are going to use any of those pipes as barttery interconnects etc obviously the length used would be about 8" to 10 ", so to get the resistance you would have to divide the above resistance figures by about 12.

To give worst case example the 1/2 pipe 1.25mm at .0013 ohms per 10ft divide by 12 =.0001ohms per foot
THe loss across that pipe used as a battery interconnect would be using 24v connected to a 100 amp load = 40ma
Now lets see how that compares to using a #2 cable and 2 lugs cable resistance = .00052 plus 2 crimped lugs at .00046 total resistance = 99ma loss

Any talk about wondering about losses for 1000 ft of ANY 1/2" copper pipe can clearly be shown to be a pointless exercise. and it way surpasses using #2 cable and the fact is most people would only be using #4 cable as interconnects.With far far greater losses.And as I said in a much earlier post use 3/4 " copper pipe.No matterif it has many impurities its still far far ahead of #0 cable for battery interconnects

Tests involved to measure lug on wire resistance and mechanical strength.
the tests involve #4 cable and closed ring closed tube copper lugs 2mm thick

1.Lug compressed with 500lb pressure on 3 serrated teeth jaws. resistance .00023 ohm.Lug then tested for breakaway

.seperated from cable at 223lbs pull

2,Lug compressed with 500lb pressure on 3 serrated teeth jaws then lug heated and filled with resin cored solder.

resistance .00015 seperated from cable ..failed as cable broke before cable seperated . test pull 325lbs

3. lug and cable resin cored soldered only. resistance .0008 seperated from cable at 127 lbs

As you can see solder only is not good. As a further test the joint melted when a 140a load was connected to the cable and a 12v battery to the lug. Obviously not good.

As you can see I didnt get much work done for employer the day I did all these tests, believe it or not it took 3 of us to do the tests .my work partner to verify the results ..As to do any destructive testing a workplace safety officer has to be present.
Hope some of this helps people understand a little more about cables lugs copper pipes..

-Bill

PS: (5-19-2012) here is a short thread that shows some bus bar/connector options:

Battery Bank Cable Lengths

BB.

Re: Working Thread for Solar Beginner Post/FAQ

Add this link to our Solar Beginner Post:

Emergency Power

Basically a very long thread that starts from the beginning with a few vague requirements through design and assembly for a "portable" solar RE off-grid power box.

And here is another example by Mike90045 called the Solar Monolith:





Update pictures/information here.

-Bill

mike95490

Re: Working Thread for Solar Beginner Post/FAQ

BB. wrote: »

And here is another example by Mike90045 called the Solar Monolith:
Unfortunately, Mike's instructions to make this unit have disappeared from his original link--but it is very simple and straight forward.

-Bill

I'm looking into that, and will repost them on my site, or directly here.

I have better resolution sketches for the cut schedule, but can't get the larger files to upload here. send me an email if you want.
Cut from a sheet of plywood, and some 1x4 furring strips. Lots of wood screws. Has taken a beating since 2001, and still going strong.

Now linked to my facebook page, which is open access to this album:
http://www.facebook.com/album.php?aid=2074858&id=1196643274&l=7e66e96c3c
- heres a pictorial of my Monolith construction:
http://tinyurl.com/SolarMonolithConst

BB.

Re: Working Thread for Solar Beginner Post/FAQ

One of our members has posted a sample SolarCity lease here:

Residential Leasing -- Post 114+

Thank you "Jburgess".

-Bill

BB.

Re: Working Thread for Solar Beginner Post/FAQ

One of the major battery killers is Sulphation/Sulfation... Usually caused by under charging, but many times caused by too large of battery bank (capacity) for the amount of solar panels / battery charger capacity.

Some information on sulphation and what it looks like inside the battery (reply to question about why batteries are not charging properly):

Windsun wrote: »

What you have is a classic case of sulfation, mainly from having far too much battery capacity for the size of the solar panels. A single pair of L16's would have been far better - and a lot cheaper.

Here is a fairly good writeup on sulfation http://www.boatelectric.com/sulfation.htm

You can try using one of the battery desulfators - they work.. sometimes. We have seen them bring back batteries from 5% to 70% capacity in some cases, in other cases there was only a marginal increase. A lot depends on factors you cannot see without actually tearing the battery apart, which kind of renders the battery unusable. In your case it might be worth trying on half the bank, but no guarantees it will bring them back. Given the age of the batteries, you might be better off just buying a new pair. You can probably get around $10 each for the old ones as recycle.

-Bill

BB.

Re: Working Thread for Solar Beginner Post/FAQ

Here are a couple threads that discuss Solar Tracking Systems and some recommendations:

Eletrician Going Off Grid - Sizing / Questions
RedRok Solar Tracker

-Bill

BB.

Re: Working Thread for Solar Beginner Post/FAQ

I am a big believer in building a "balanced" off-grid solar PV system... That means after measuring/estimating your loads, sizing the battery bank and sizing the solar array--You need to next size the battery charger and genset to recharge your battery bank in a cost effective/fuel efficient manner..

Here is a neat thread that details the journey of "SteveK" trying to charge a smallish battery bank with a 1,600 Watt Genset and how much study and research that can take just to find the "right" battery charger:

Question about battery charger selection with EU2000 generator.

-Bill

BB.

Re: Working Thread for Solar Beginner Post/FAQ

One of the first thing we ask new posters is have they looked at conservation... Here is a couple of threads:

• This poster, cut natural gas use by 1/2, cut electrical use to 1/4 of original bill

I will try to update this post as I run across other threads about conservation successes.

Or post your own here and I will merge them into this post.

-Bill

Added 4/10/2013:

C_Heath wrote: »

Hey guys, new guy here again. Thanks for the many tips. You guys have put money in my pocket and I mean literally. My power bill was $200 on the nose in Feb, compared to $106 in March! where I come from thats HALF!

I did have some help from a new wood furnace that I installed. I did have to purchase that but I had been wanting it for years. This had the most impact, heat pump switched to OFF!

The rest was just some conservation and talking to the 4 females in the 2000+ sf home. Now that they are on board, I think we can really start conserving. Yesterday, I went off the deep end. I installed timers on all cable boxes and TV's. I also added a timer to each of the 2 freezers we have. They are currently being monitored but they are both full and should have no problem keeping the extremely cold temps whiles they are in time out.

So heres the big one. I bought a timer for the water heater. I can install it but I don't have a voltmeter so I called my electrician buddy. He called me and told me NOT to install that thing no matter what! I was like why?????? He said when you cut it off, the water temp will cool and then it will take so long to heat back up that it will run longer that it does when it doesn't have a timer and will cost me more. Well, like i say, I went of the deep end so I'm not going to tell him but I'm installing it anyhow. I gotta see for myself.

Thanks again guys for all the help. Im shooting for $75 or less in power. Ill need to be what? around 800 kwh? This is doable.

8/23/2013:

A happy poster here... He has knocked off 40% (maybe 50%) off his energy consumption, and added a grid connected (GT or Hybrid solar--not sure) and off grid solar power system ($0.47 per kWH summer peak rates, ~$0.11 per kWH off peak rates--Australian Dollars). And he further reduced his costs with utility buyback of his excess summer generation.

Note that many Grid Tied installation need government rebates and utility rate plans that provide incentives for customers to install solar... What the government gives, it can take away (or at least try). My two cents--Going solar is not money in the bank. It can give you a nice return, but the future outlook is always mixed in a tough economic environment.

HELP needed; Wire size for minimum voltage drop, etc.; full house 12v lighting off-grid

Sascha wrote: »

ALL THANKS TO THE GREAT MODERATORS'S OF WIND-SUN.COM ADVICE; CARIBOOCOOT - MARC, BB - BILL AND ALSO A NUMBER OF MEMBERS WHO HAVE CONTRIBUTED TO MY THREAD.
PLEASE NOTE; MONEY IS NOT THE MAIN AIM OF WHAT I HAVE ACHIEVED AND STILL WANT TO ACHIEVE (IT HELPS TO SAVE SOME) BUT INDEPENDENCE & THE KNOWLEDGE OF CONTRIBUTING TO PRESERVATION IS PRICELESS.

Hey, the Australian government tried to half their buyback incentive a couple of weeks ago due to cutbacks, etc. It was already all approved and announced as definite but then 2 hours later they reversed their decision. Phew!!!

A lot of people started teaming up to file a big lawsuit against the government trying to renege their 10 year guarantee. I guess it would have ended up costing them more in legal fees than worth.

Just shows that a governments word can be taken pretty lightly if at all. Worry every time there's an election, caucus or other political games going off.

Our system was what we could afford at that time, 2.2Kw but there are people out there with roofs covered to the brim with solar panels, who have spend $20000+ after rebates and they would have been hurt badly because all of a sudden their payoff period could have gone from say 4 years to 15 years.

I'm very happy with our set-up, just wish we could have afforded a larger one.

Our bills so far:
Nov 2010 - $211.70 debit
Jan 2011 - $262.75 debit
Mar 2011 - $270.90 debit
May 2011 - $251.90 debit
Jul 2011 - $326.30 debit
Sep 2011 - $194.15 debit
Nov 2011 - $42.65 debit
Jan 2012 - $4.00 credit
Mar 2012 - $96.05 debit
May 2012 - $29.20 debit
Jul 2012 - $69.85 debit
Sep 2012 - $7.40 debit
Nov 2012 - $108.80 credit
Jan 2013 - $131.35 credit
Mar 2013 - $170.50 credit
May 2013 - $28.95 credit (credit accrued $439.60)
Jul 2013 - $1.55 debit

The OG solar was up and running in August 2011 and then the UPS & battery bank in June 2012. Some data from our bills: (beginning to end of) Sep 2010 - Sep 2011 debit $1517.70, Sep 2011 - Sep 2012 debit $237.15 Sep 2012 - Jul 2013 credit $438.05.

I'm looking forward to the next bill to complete the cycle, $2000/year difference from BEGINNING OF OG solar installation would have been nice but I'm more than happy with it. So far we have paid of the OG solar in two years rather than 3.5 years as estimated (that was the estimate from the installers point of view which I would have more realistically capped at 5 years). I'm now estimating to have paid off the whole set-up in under 5 years, this would include all parts, wiring, 2 x Victron UPS's and the battery bank, needless to say I am not using the second Victron yet; currently only 1 is hooked up until we can afford to double the battery bank. This I may now leave until after the life expectancy of the existing battery bank, rather than join a new bank to the old one, which I understand is not good practice after more than 6 months as the new bank will only perform as well as the old one.

I hope this thread I've started will encourage others to follow and learn from it as I have.

I'll submit the final figures next month, when we get our bill. I'm not expecting a credit due to bad weather and very little sun but who knows, the teenage son passed his drivers licence recently so he doesn't spend too much time on his computer, x-box and such, all with lights on most of the time.

I'm now looking forward to starting some passive solar heating (winter) projects and soon test the design of the house, incorporating numerous airflow vents (summer). So far no air conditioning, even though Western Australia needs it in summer. Maybe we've all gone 'too soft' with all the mod-cons available now, people have lived without them for centuries!

Anyone out there; what incentives does your country give you to go solar?

I think we are pretty fortunate here, in Australia, for the time being. There hasn't been many sunny days lately but we've accrued enough credits to not to have to pay for electricity and hope to maintain the battery bank so it'll work a few years. I'm happy with free electricity, even if our credits are used up during winter.

PS; Electricity went up by around 30% in the last 2 years which has not been accounted for in my estimates.

Added 10-31-2013:

NorthGuy wrote: »

Originally Posted by Rossman

Yeah, it can be cloudy here by times for sure. I have been trying to plan using the winter sun hours/day (~4.2h)

The worst is when you get a long cloudy period. You would need to run a generator a lot when you do.

Originally Posted by Rossman
So you use a gas range & dryer I guess, NorthGuy? Do you have a dishwasher? What do you do for heating? We are thinking of an electrically efficient gas furnace...and due to new building codes we need to install an HRV, so have been looking at the Venmar EKO unit.

I do have Natural Gas here. I have gas furnaces (in home and garage), tankless gas water heater, gas range, gas dryer. My generator is gas powered too. I also have a wood stove.

From the electric viewpoint, I have water pump in deep well, big fridge, dishwasher, washer, microwave, very small electric water heater to smooth undesirable effects of tankless heater, coffemaker, toaster, some in-floor heating in the bathroom (evening only), some pipe heating outside, computer server which runs 24/7, several home computers (two used frequently), lighting, TV (not used much). There must be something I forget.

We consumed twice as much before we went off-grid. We replaced nearly everything with new efficient models, changed our habits a little, and as a result conserved a lot.

Originally Posted by Rossman

My main concern is having an undersized system so if I have to spend a few extra grand to ensure that's not going to happen, so be it. Better to be over-sized than under-sized as I see it.

You can plan for expansion. Say, you install X number of panels, but design everything so that you can easily install a little bit more. In reality, it is very difficult

Battery bank is more difficult to expand. However, I have rather small one, but I don't feel that it's too small for me.

BB.

Re: Working Thread for Solar Beginner Post/FAQ

Here is a nice thread with several links on how to build/assemble your own solar PV panels:

mike90045 wrote: »

panel building:
http://fieldlines.com/board/index.php/topic=145005.0

In case the above link "breaks" (edited above and below to perma links--I think):

Oztules' series:

http://fieldlines.com/board/index.php/topic,144982.0.html
http://fieldlines.com/board/index.php/topic,144995.0.html
http://fieldlines.com/board/index.php/topic,145004.0.html

Still don't recommend people build their own to save money--But some good information for those that want to try.

-Bill

BB.

Re: Working Thread for Solar Beginner Post/FAQ

A short thread on:

Solar panel damage from hail storm (big hailstones)

Also some comments on roofers and insurance--And what to watch for.

-Bill

BB.

Re: Working Thread for Solar Beginner Post/FAQ

Some discussions about VFD (Variable Frequency Drives)... Basically a variable frequency inverter with (typically) three phase output. Used to soft start motors (handy for 3 phase well pumps, or pumps with well head starting capacitor) and can also turn an AC motor into a variable speed motor (very handy for pumping applications).

WELL PUMP and Inverter QUESTION
Wind/solar for large scale pumping etc (out of my depth!)
could use knowledge - using Gould jet pump - transfering from 230vAC to ? DC (new link/thread 10/27/2012)
Help required to design off grid system (information on possibilities to connect "standard VFDs direct to solar panels) (new link 1/13/2013)

And from a new poster, link to solar VFD (looks interesting):

VeichiElectric said:
u really should read this article about solar pumps:
https://www.veichi.org/solutions/water-supply/pump-vfd-or-vsd-for-constant-pressure-water-supply-system.html (updated link -BB 1/1/2019)
In your case I wonder if a solar PV inverter would help or not.

-Bill

1/7/2017:
Dave Angelini said:
Grundfos has been doing solar water pumping for 30 years in the Americas and over the seas
http://us.grundfos.com/about-us/news-and-press/news/Pumped-by-the-Sun.html
They have some really nice plant tours down in the Fresno area of California.

BB.

Re: Working Thread for Solar Beginner Post/FAQ

We get questions about how to "recover" a sulfated/failed battery--Here is some information about AGM battery "recovery":

mtdoc wrote: »

FWIW there are some AGMs that claim to have a shelf life of "up to 2 years at 25* C".

Perhaps this is just marketing hype?

Checking the voltage at rest is a good idea.

BB. wrote: »

Here is a thread how one company (Concorde) recommends to "recover" their AGMs... Not supposed to apply to any other brands of AGMs:

Sulfated Lifeline Concorde AGM Batteries

And here is a great thread from DapDan with information on how one place recommends to restore AGM batteries (new catalyst caps, adding water to cell, etc.):

Low rest voltage on GNB absolyte IIP cells

In the end, trying to do "extreme" things to batteries should be done in a safe area and always under some sort of supervision/monitoring (don't want to overheat the cells and blow acid around) and performed while wearing appropriate safety gear/gloves/face shield/water/hose/baking soda nearby/etc.).

And--if the cells are otherwise scrap--if you can try some of the above things (if done safely)--you are not loosing much anyway.

Add this link to AGM documationation (Dec 29, 2012):

westbranch wrote: »

this doc is from C&D and will give you great insight to what is happening inside those AGM's, especially if you try an EQ...

http://www.cdtechno.com/pdf/ref/41_2128_0212.pdf

enjoy...

-Bill

Lee Dodge

Re: Working Thread for Solar Beginner Post/FAQ

BB. wrote: »

...snip...

[*]Know your loads--You need to measure your loads... Watts*Hours (average power * time) or Amps*Hours (for 12 volt / DC loads). Average usage per day and by season (more sun in summer, less in winter -- same for PV power). This is where you set your expectations for your solar power system. Generating the solar power is expensive (~$1.00 TO $2.00+ per kWhr vs $0.10 per kWhr for utility power).
...snip...

-Bill

Bill-

Thank you for your efforts in collecting information on thermal and PV solar.

I would suggest modifying your statement (from four years ago) about generating solar power is expensive (~$1.00 TO $2.00+ per kWhr...) to say generating solar power off-grid is expensive. I find in our area that generating solar power with a grid-tie system is very cost competitive with utility power. For three systems that I am tracking, the estimated costs amortized over 25 years range from about $0.064 to $0.082 per kWh hour, which is less expensive than the utility rate from the two different utilities here of $0.103 and $0.130 per kWh (http://www.residentialenergylaboratory.com/comparison_of_pv_systems.html).

The difference in these costs (to me, at least) is that solar PV grid-tie systems are not just for fat-cats and/or nerds that want to play with solar, but rather, they are a reasonable economic choice in many geographic areas for people that want to live with electricity but want to minimize their carbon and pollution footprint.

Lee

niel

Re: Working Thread for Solar Beginner Post/FAQ

i think bill can leave his statement as it is because even being comparable to utility power we all agree utility power is somewhat expensive anymore. there are some exceptions of course, but one does need to know that one isn't going to get their bill reduced or eliminated with a few hundred dollars. it still isn't cheap even though it is cheaper now than it was.

BB.

Re: Working Thread for Solar Beginner Post/FAQ

Hi Lee,

I agree that Grid Tied Solar (Grid Interactive, GT inverter+solar panels and no battery bank) is often competitive or even less money that grid power--Although utility/state PUC rules can affect the rate of returns dramatically (and some utilities do not support GT solar).

However, for Off Grid (or hybrid solar) Inverter systems (solar panels+charge controller+battery bank+off grid or hybrid inverter) still (to me) appear to be fairly expensive when compared with Grid/Utility Power... That was the $1-$2+ per kWH I usually refer too (one or two folks here have gotten their self installs down towards $0.80 per kWH for off grid solar).

However, I am not in the business--this is just standard sizing rules and retail pricing/estimates of maintenance costs over ~20 years of system life.

Do you have any cost of power estimates for Off Grid or Hybrid solar PV systems?

-Bill

Lee Dodge

Re: Working Thread for Solar Beginner Post/FAQ

Bill,

My dispute is not in the rate that you quoted, but rather that you labeled that rate as the cost for "solar (electric) power." As you have done elsewhere, you sometimes distinguish between a rate for off-grid and grid-tied, which differ by a factor of 5 to 20. Your rate for grid-tied solar electric energy is higher than my value, but you tend to be conservative and I try to be technically accurate, and to include subsidies as they happened to exist when systems were purchased. Also, the systems that I am tracking are in a high solar insolation area.

You have heard from thousands of people that want to spend a few hundred dollars and never pay an electric bill again, and I think your statements are meant to slow them down. However, in my case, I spent between $5,000 and $6,000 for a grid-tied solar PV system, and pay only a connection fee of about $7.50 a month, at least for the 2 years of operation so far. (Note - no A/C required here.) So I would suggest to just modify your thread to include both costs and let folks make their own decisions. I would like this forum to encourage people to use solar energy where it makes economic and environmental sense to them. (This point may already be made in this thread, but I did not see it.)

I am not tracking any off-grid or hybrid systems, and do not have any costs for them.

Thanks again for working to collect these resources.

Lee

BB.

Re: Working Thread for Solar Beginner Post/FAQ

Lee,

If you wish, I would be very happy if you listed your estimated costs/installation/maintenance/kWH per year/etc.. for GT Solar from your experience.

Again, I am not in the business and would be very happy to have it here in this thread and show people how to understand the overall costs/returns for such systems.

I agree that the price of panels has fallen dramatically over the last few years--And so far, the cost of hardware/labor has remained relatively flat. With the 30% Fed Tax credit (and sometimes other local credits/payouts) can make GT solar break even or even save a fair amount of money.

-Bill

Cariboocoot

Re: Working Thread for Solar Beginner Post/FAQ

The problem is: not everyone lives in the same place. This makes it impossible to quote one price per kW hour that works everywhere. It doesn't matter if you're talking grid-tied or off-grid.

For the longest time GT systems did not make economic sense unless you had tax credits/rebates/FIT programs to help with the cost. Now that utility rates have gone up and panel prices have come down this is no longer the case.

At least not everywhere. :cool: Still makes no sense whatsoever up here!

Lee Dodge

Re: Working Thread for Solar Beginner Post/FAQ

As the costs for solar PV panels have come down and as subsidies have been put in place for solar systems in the U.S., the costs for solar PV generated electricity has come down to roughly similar rates as standard electric utility rates (typically within a factor of 2). Specific data are available for three solar PV systems installed within the last two years on new homes in south central Colorado (Salida). The projected electric production costs for these 3 systems amortized over 25 years shows electric rates of $0.064/kWh, $0.080/kWh, and $0.082/kWh, for systems #1, #2, and #3, respectively. These costs are based on measured electricity production for the first year or two and projected to 25 years assuming a 0.65% degradation factor per year. The electric costs for these grid-tied systems are roughly 1/5 to 1/20 of the cost for off-grid systems. These projected costs are lower than the current electric utility costs for systems 1 and 2 of $0.103/kWh, and for system 3 of $0.130/kWh. These rates are close to the U.S. average for electric rates.

The assumptions and analysis details are provided here, but some of the results are described in this post. The costs for system 1 (3.15 kWh DC) before and after subsidies were $18337 and $5451, or $5.82/kW DC and $1.73 kW DC. The costs for system 2 (2.82 kW DC) before and after subsidies were $16,400 and $6386, or $5.82/kW DC and $2.26 kW DC. The costs for system 3 (3.68 kW DC) before and after subsidies were $17,985 and $9199, or $4.89/kW DC and $2.50 kW DC. Systems 1 and 2 were installed in 2010, and system 3 was installed in 2011. An additional cost of $2812 for parts and $500 for labor was assumed for inverter replacement at 12.5 years. The PV system value was assumed to be zero at 25 years, and no disposal costs were included.

These costs were for an area with relatively a high solar insolation of 5.78 kW/sq. m/day, and a relatively cool average temperature, both favorable for good performance of solar PV. To see average solar insolation values in your area, enter your zip code at PVWatts. Lower solar insolation values will increase solar electric production costs proportionately.

bill von novak

Re: Working Thread for Solar Beginner Post/FAQ

Below is a list of common solar mistakes. They come up often, in the form of questions on boards like this one. They are all reasonable questions for someone starting out in the solar field, but when you look more closely at the issue, there are some problems as discussed below.

Please don't take this message as "you're dumb if you think these things." I learned that most of these were mistakes by actually making those mistakes; I spent years underestimating costs, trying to install unapproved grid tie/grid interactive systems, and scratching my head when my systems didn't produce half the power I thought they would.

========================================================


Mistake #1 - "I just got a bunch of solar panels! How do I hook then up? I spent most of my money on the panels so the rest of the stuff can't break the bank."

The Big Idea:
I came across a cheap site on the Net and I got as many panels as I could, because these deals can't last! Getting enough panels must be 99% of the battle; the rest is just nuts and bolts and wires.

Reason this is a bad idea:
The inverters, batteries (if off grid) and the other BOS (balance of system) hardware can cost as much - in fact often costs more - than the panels themselves. You need lots of wire, since solar panels are usually mounted at least vertically distant from the load they are driving. The wire you need will often be expensive; for battery wiring you could easily pay a dollar an INCH for terminated cables. You need fuses or circuit breakers, DC disconnects that can handle high voltages and currents, inverters to use the power, charge controllers/batteries if it's off grid. You need a mounting structure that will keep your roof on your house and prevent those panels from becoming spinning 40mph battering rams in a bad storm. And all those things are very important if your goal is installing a safe system. Wiring and circuit protection are two things you CANNOT skimp on - and this is even more important for people experimenting with solar, because you're going to make mistakes.

We see this question a lot because people see a good deal and buy a bunch of solar panels and want to make them work. Nothing wrong with that, but if you are money constrained, it's much better to buy half the number of panels and spend the rest on good inverters, batteries etc.



Mistake #2 - "I just want to feed a little power back to the grid. I saw this grid tie inverter on Ebay for $99 . . . ."

The Big Idea:
Getting grid tie approval sounds like it's a pain in the butt, and I just want to generate a LITTLE solar without all that paperwork.

Reason this is a bad idea:
It's not hard to design a grid tie inverter that feeds power back to the grid. In some ways it's easier than designing a standalone inverter, since the impedance of a grid tie connection is much more constant, and you don't need to provide a time base. But there's a reason that grid tie inverters tend to cost a fair amount - they meet NEC requirements for power factor, safety and anti-islanding. And again, these things are even MORE important for experimenters than they are for professional installers, because experiementers are going to make mistakes - and you'll want that extra level of protection when you accidentally island your loads.

Also, UL listed grid tied inverters are going to be part of any serious grid tie installation. You'll learn more about real installations by working with real hardware.

Mistake #3 - "I don't want to do grid tie, I just want to charge a small battery bank with solar, run off that, then use the grid only when they get low."



The Big Idea:
Getting grid tie approval sounds like it's a pain in the butt, and this way I can avoid all that hassle and still generate most of my power via solar; just add a few batteries to my system.

Reason this is a bad idea:
Batteries are the biggest cost in any off-grid power system. Not because they are the biggest cost up front - but because they don't last long. Golf cart batteries will give you around 500 cycles discharging to 50%, which is around a year and a half of solar off grid usage. People don't want to replace their batteries every year and a half; it's heavy lifting, they're full of acid and lead, you have to recycle them, the new ones cost money, it's the dirtiest part of the system and you ruin your pants etc etc. So they find ways to make them last longer. They use larger cells that a) last longer to begin with and b) only have to be discharged to 30% (or some other lower number.) This extends their life.

For people on the grid the answer is much easier - never cycle them. Use a hybrid inverter that keeps them float charged all the time. This allows batteries to last much longer. Telecom batteries in such applications (generally called UPS, or uninterruptible power system applications) can last twenty years because they are not cycled and kept at their "happy" state of charge. Only during the rare blackout do they see cycling.

The reason Mistake #3 is a mistake is that it attempts to do the exact opposite of all of the above - it attempts to use a small battery bank and cycle it hard every single day. This means you'll go about a year between battery changes if you're lucky, and you'll be assured of a lot of heavy lifting and buying of new batteries.

Mistake #4 - "I get like ten hours of sun a day so I shouldn't need a big system."



The Big Idea: Since it's nice and sunny ten hours a day up here I should be able to generate close to full power ten hours a day - so I don't need as many panels.

Reason this is a mistake:
Equivalent sun hours refers to the total full power sun the system sees. Most systems really see full power for only a few hours a day; the rest of the time the sun is at an angle to the panels and shining through too much atmosphere to get to full power. Even tracking arrays only help a little with this. Thus 12 hours of daylight might give you only 6 hours of _equivalent_ direct sun - and direct sun is what you have to base your total energy output on. The NREL website has good maps that show you how much equivalent direct sun you can expect in various locations, and it's almost always less than you think it will be.

(continued below)

bill von novak

Re: Working Thread for Solar Beginner Post/FAQ

(post continued)

Mistake #5 - "My neighbor has a two kilowatt system but he uses 600 kilowatts a month! That's not helping him at all."

No Big Idea here. This is a common misconception; it confuses power (kilowatts) with energy (kilowatt-hours.) A two kilowatt system, if exposed to four hours of equivalent direct sun a day, will generate around eight kilowatt-hours of energy. Actually somewhat less due to efficiency losses in the wiring and inverter.



Mistake #6 - "I don't want to run everything, just air conditioning and my efficient refrigerator."

The Big Idea - It might be tough to run a whole house, but just a few appliances should be that much easier.

Reason this is a mistake: Air conditioning, refrigeration, and pool pumps (if installed) are the biggest users of energy in a house. (Resistance heating can be an even bigger energy user, but it's madness to try to run resistance heating on solar electric systems.) A small standalone system is much better used to provide some LED lighting, backup power for laptops and radios etc. Even better, do a small grid tied system and offset some of the load from the bigger users.



Mistake #7 - "This system is real expensive if I get it installed. But I looked online and panels are really cheap, so I'll do it myself to save money."

The Big Idea - Greedy installers make solar way more expensive than it needs to be, so doing it myself will save me lots of money and make me energy independent from the bureaucratic power companies.

Reason this is a mistake: Much of the cost you see on an installer's estimate has to do with the BOS components he will have to supply - heavy gauge wire, DC disconnects, racking etc. These are the easy to overlook pieces that you will need to install the system. Once you add all those in you'll see the actual labor costs are fairly low compared to the costs of the parts. Thus you really aren't saving that much.

For people who really want to save money, AND have experience as an electrician, you may be able to find an installer who will let you do most of the work. They will take care of the parts that are dangerous (like wiring the DC disconnect) and annoying (like applying for permits and scheduling inspections) and leave you to drill holes, bend conduit and pull wires. In general you have to know someone very well to do this, because the installer won't want you to botch the rack installation then get sued when your roof leaks.



Mistake #8 - "Why can't you combine solar-PV and solar hot water panels?"

The Big Idea - If solar panels get hot anyway, why not cool them with water, then you can use the water for your hot water! That kills two birds with one stone.

This is a not a bad idea but does not work for domestic hot water. To get 120F water in your tank your outlet water will have to be close to 130F - and that means the panels themselves have to be 140-150F. It _sometimes_ works for pool heating since panel outlet temps on a well designed pool system rarely rise over 90F, due to low water temperatures and high flow rates. This can keep the panels cooler and give you some heat. The drawbacks of this are increased complexity (two connections per panel) and safety issues (high voltage DC and water don't mix well.)



Mistake #9 - "I need to add more batteries! I don't have long enough run times over night/cloudy days/in the winter."

The Big Idea - If my battery bank is 'running dry' too soon I can just add batteries and solve the problem.

Reason this is a mistake: In general, a solar PV system needs to have its components balanced. Loads against battery capacity, loads against solar array - even batteries against solar array. Too large of battery bank or too small of battery bank creates their own sets of problems. Many times, people have too large of battery bank, draw too many kWH per day, and/or don't have enough solar panels to recharge the bank quickly and completely. Just adding batteries usually makes the situation worse (more battery capacity takes even longer to recharge with same solar array, have higher losses, may not last as many years because of chronic "deficit charging", and cost more to replace the next time).

In the "olden days", batteries were relatively inexpensive and solar panels were horribly expensive. Today batteries have certainly not gotten cheaper, but solar panels have - so for many people, their days of nursing battery banks and cutting loads can be addressed by adding to the solar PV array. Batteries will last longer, recharge quicker, and during sunny summer weather you may even have the ability to run heavier loads like an efficient A/C system in your off grid home.

Also, adding new batteries to an old bank can cause problems. Dissimilar rates of charge will mean that the batteries will not balance their loads as well, and both the new and old batteries will age at a faster rate. This is especially problematic if you are just adding series strings of batteries; doubling the capacity of a two-string 24 volt bank by just adding two more strings makes balancing far more difficult. You are much better off with fewer strings of higher capacity cells.



Mistake #10 - "I want to get my grid tied system to keep working when the grid goes down! Can't I fool the inverter somehow into thinking that the grid is still up?"

The Big Idea - I spent a lot of money for this grid tie system and I don't want to sit there like an idiot in the dark if the power goes out. I'll figure out a way to keep the inverter from shutting down; that way I can back-power my house. Just when the sun is out of course.

Reason this is a mistake: First off, grid tie inverters go off line because it's very important that they do so when the power goes out for the safety of line workers. It is critical to ensure that grid lines are de-energized during blackouts so utility workers can make repairs without getting killed. And you're not just feeding 240 volts back to the grid; under the right conditions you could backfeed local transformers and generate thousands of volts on lines that should be de-energized. Thus there are some redundant and well-engineered systems in GT inverters to look for any faults in the grid and shut down quickly when they see them.

Secondly the grid provides a stable (and very low) impedance for grid tie inverters to work into. Generating a "small AC signal" to fool it into turning on will result in a very high impedance local grid that will cause the GT inverter to shut down quickly.

Third, even if you could fool the system into starting up, there is no way to balance supply and load. The line would very quickly go overvoltage if supply exceeds loads and very quickly go undervoltage when the load exceeds the supply.

All that being said, if you are still reading this and understand the above, there IS a way to make this happen, and it's called AC coupling. You can use a good bidirectional inverter (with batteries) to stabilize the grid and provide a sink/source for power when loads do not equal supply; you essentially create an "island" of power while the grid is disconnected. Outback has a white paper on this. However this must be designed in from the beginning; it's not something you can add to a conventional GT system when the power goes out.

(Thanks to ggunn and BB of the wind-sun forum for additions to this list.)

BB.

Re: Working Thread for Solar Beginner Post/FAQ

New poster "leaf" has a really nice set of charts that compare battery voltage against different rates of discharging and charging (as well as resting voltage readings).

leaf wrote: »

Am trying to upload the charts I am using...

[note charts are from: I believe those charts are from Home Power #36, August- September 1993. Lead-Acid Battery State of Charge vs. Voltage ©1993 Richard Perez.
Here is a link: http://www.scubaengineer.com/documen...ing_graphs.pdf

vtMaps]

I don't quite a agree with the resting voltage line (I think the voltage is a bit low)--But it shows how to estimate a battery's state of charge while operating.

Note, where the charts "flatten out"--the room for error estimating state of charge is pretty high.

-Bill

BB.

Re: Working Thread for Solar Beginner Post/FAQ

CDN_VT has supplied some videos about soldering:

Soldering 101 FYI

-Bill

vtmaps

Re: Working Thread for Solar Beginner Post/FAQ

BB. wrote: »

New poster "leaf" has a really nice set of charts that compare battery voltage against different rates of discharging and charging (as well as resting voltage readings).

I believe those charts are from Home Power #36, August- September 1993. Lead-Acid Battery State of Charge vs. Voltage ©1993 Richard Perez.
Here is a link: http://www.scubaengineer.com/documents/lead_acid_battery_charging_graphs.pdf

vtMaps

niel

Re: Working Thread for Solar Beginner Post/FAQ

you're right vtmaps. credit is due hp mag.

BB.

Re: Working Thread for Solar Beginner Post/FAQ

Thank you Vtmaps for the original source of the battery voltage curves.

Poster ChrisOlson (and others) has some good advice here for "swimspam" :

Choosing a good generator
genset alternator failure (and if your generator is not generating AC? What to look for/do--Thread started by "Unicornio" from Spain)
Demonstration of Generator Support (A couple inverters that will share AC loads with the generator--smaller generator with large load support)

End result--you get what you pay for.

-Bill

Add 12/6/2012:

ChrisOlson wrote: »

BB. wrote: »

The smallest genset I have seen here so far that can be (more easily) configured to auto-start (automatic choke) is probably the Honda EM4000SX that Chris Olson is using. The choke/mixture is controlled by the electronic engine controller.

I'd like to point out that the little 46538/46539 Champion generators also have an auto-choke and I have mine configured for auto-start with the Trace/Xantrex GSM on the SW Plus inverter. When our Generac would fail to start in cold weather I used the Champion as a backup with the auto-start and it works fine.

It is basically a three-wire start generator and you only have to tap into the wires on the back of the Combination Switch to do it, which is quite easy to do.
--
Chris