Home-Brew vs. Off-the-Shelf

SolarJohn · August 2009

A recent thread included a lively discussion concerning the best way to switch a load on and off based on battery voltage. Since that thread is now closed, I hope to continue the discussion here.

A home-brew project may result in a finished product that costs much less than an off-the-shelf product, but there are many pitfalls. To succeed, the builder needs to have tools, a good knowledge of electronics, and good building skills. If the finished project doesn’t function properly, the builder needs equipment, at least a DMM, to troubleshoot. An oscilloscope would be ideal. Assuming that the fault can be found, the user may need to replace a failed component. This might require an on-line order, with shipping charges and possibly a minimum order of $25.00 or so, just to replace a 49 cent IC.

If the builder doesn’t have a good understanding of electronics, he/she may not be able to determine the cause of the problem. Consider this example: Although a circuit may function as it was designed, oscillations may result from battery voltage sags and surges caused by applying and removing the load. In this case, the user needs to know how to modify the circuit in order to change the operating parameters.

Circuits are often drawn with components such as surge protection devices omitted. If the user fails to install these devices failures will occur. Back emf from energizing and de-energizing a relay is an example of this. Additionally, failure to filter input lines might result in false-triggering.

Circuits sometimes include relays or other output devices that are not hefty enough to handle the load. The builder will need to know how to modify the circuit to meet his/her own needs.

PV system battery voltage for a 12-volt system can vary from less than 11 volts to more than 15 volts. If the circuit is to be powered by system battery voltage, it needs to function properly within this range. Some designs I’ve seen will not. If the device depends upon a wall transformer for its operating power, it is not optimized for minimal power consumption.

On the other hand, commercial products are typically optimized for minimal power consumption, will function correctly with varying input power, are protected from voltage spikes and back emf, and are well constructed, packaged, and documented. Products that are to be installed in harsh environments are protected from the elements. Commercial products often include features that enhance performance and contribute to ease of use. Commercial products usually include a warranty, and perhaps on-line technical support. These features are often lacking in home-brew projects.

Perhaps the best reason to choose a commercial product is for its reliability. Life can get pretty uncomfortable when the grid fails, and your PV system malfunctions on the coldest night of the year. Also, do you really want to risk having the food in your refrigerator spoil by trying to get by on-the-cheap?

John

BB. · August 2009

Re: Home-Brew vs. Off-the-Shelf

There is a strong Do-It-Yourself in solar RE... And for people that want to try to build something themselves and others that want to help--I have no problem with it (apparently, contrary to my reputation :roll: ).

There is an entire range of outcomes with any project and as long as the DYI'er has addressed safety issues and understands the limitations of the project/design/construction, why not...

I have helped maintain a wire wrapped computer mounted on a geological survey ship for a summer (salt air, vibration, wire wrap--with a permanent o'scope attached somewhere looking for next intermittent failure) to prototyping and design, layout, and production of large computers... Everything has its place.

I have seen extremely well done vector board prototypes/one-offs -- and terrible "commercial" products (some of them looked very nice but had fatal design flaws).

In the end, posters will have to way their options and go from there.

The original thread--the poster was just working with a cooler with a thermoelectric cooling module in it... The amount of food was small and it would be very easy to verify proper operaton of the circuitry. So--the "risk" is low and it is up to the original poster to weigh the options.

I am not sure where this thread will go... I am willing to leave it open but fear that there is little "solid" to discuss. The other thread had the circuits and the application (and yet was closed--and is inappropriate to continue the discussion here--otherwise why close the original thread). This one has neither circuits or an application.

-Bill

john p · August 2009

Re: Home-Brew vs. Off-the-Shelf

I agree in many ways your comments. that if the builder of a published circuit is going to have some problem after it is constructed he does need enough knowledge to troubleshoot. If a person does not feel confident he can build and possibly troubleshoot then it would be wise to not start construction.. But that goes for anything not just electronics...
But dont agree that all bought electronic /mechanical items are "just wonderful" and well designed and will perform as specified.
Read through all the threads on this and other forums like this and see just how many complaints there are from certain manufacturers... one very bad example I noted was a vertical wind generator that virtually fell to pieces when tested..bad welding and poor electronics.. there have been noted some charge controllers from certain manufacturers are usually faulty.. Many cheap inverters same problem..
you want example.. I bought one rated at 1000 w continuous it could only put out 380 watts.. it also had a idle draw current of 3 amps . and even with fan on it got very very hot.. the supplied input cable was about #10 with clips rated at max 20a..... And yes it came with "warranty" they would not honour. nice instruction booklet written in Chinese only... is this the "quality" manufactured items you refering to??
I know what you are refering to when you say no back emf protection and problems with voltage sag effecting the functioning.. I also in a post asked the designer of that circuit the same questions..
Im not going to say the circuit I provided is perfect.. but it is a proven design and many made over the years and it can work with any input from 10 to 16v. and has adequate input filtering..
With regard to that original post what everyone seemd to have missed is .. he had a simple set up a solar panel a battery and a little cooler.. To me it seems obvious he was not wanting to spend one cent more than he needed to.. and he also mentioned he would build the switch if he had to.. that to me says he knew how he just lacked a simple cuicuit.

I think this is a little dramatic ..Perhaps the best reason to choose a commercial product is for its reliability. Life can get pretty uncomfortable when the grid fails, and your PV system malfunctions on the coldest night of the year. Also, do you really want to risk having the food in your refrigerator spoil by trying to get by on-the-cheap?
How much food could there bee in a cooler???
and he had no grid nere where it was in operation..
and if its the coldest night of the year.. just mabe the food be ok if just left out in the cold?? free refrigeration....

BB. · August 2009

Re: Home-Brew vs. Off-the-Shelf

Please, lets not make this a continuation of the previous thread that ended up locked... The other thread is what it was. And this thread should not take on discussing the details of the other closed thread or the same thing will happen here.

Trying not to be too heavy handed here...

By the way, is there interest in home-brew / DYI / "dissect the unit" section for people that really want to delve deeply into this stuff? Realizing that when somebody posts a "solution/observation" that others will post their opinions of the solution and probably offer some version of their own? With less "moderation" (obviously--depends on Windsun's administration / hosting experiences and vision for the forum).

I think that this would be a worthwhile discussion topic for this thread...

-Bill B. (Moderator)

john p · August 2009

Re: Home-Brew vs. Off-the-Shelf

hmm you have a difficult job . I dont think you are being heavy handed and with hindsight mabe I should not have gone into so much detail..
The problem Isee with that original thread and ones like it and ive seen it many times before is a person usually with little knowledge about something asks for advice.. but he gets more advice than he can handle and much of it confusing to him as he does not understand all that is being discussed.
having a seperate forum for people to discuss some ones design or idea is both good and bad... good as it can get a design improved by many contributing . but bad as it takes away the idea /.circuit/design from where the person asking advice is likely to be looking for a reply.
Hope that makes sense..
example
person (a)askes for a water pump output meter.. on the "help me" forum
person (b) sees that and has a design for one so he goes on the "DIY "forum and presents it . other members then spend the next 12 days discussing its good and bad points and offering other designs.
Now what happens?? say no consensus is reached as to which is the best design even with improvements. Does then someone go back to the"help me" forum and say we cant decide on best solution for you??? or you now go to the "DIY" forum and read everything and you decide what to use?

BB. · August 2009

Re: Home-Brew vs. Off-the-Shelf

"Funny" thing is that the OP (at least as of when I closed the thread)--has not even seen any of the replies (has not logged in since his since opening post)...

The thread tended to meander because the OP was not there to "guide" the discussion to what would be useful for him (not picking on the OP--there are people who have a life outside the Internet

).

There are so many people here with good ideas, communication skills, and real world experience--that "we" can overwhelm the original question if there is no feedback from the thread author.

I don't think anyone here has an issue with content (Solar Guppy posted to a Dissertation on MPPT solar power supplies for one person looking to further his education 1/2 way across the world).

Where "we" (yep, me too) get wrapped around the axle is when we attempt to overlay our "biases" and "guesswork" on top of the poster's stated (and unstated) questions.

Neither Niel, Windsun, or I do much moderation based on content... One reason is that that there is no Cafe or Open Political threads allowed here.

It is much easier to moderate when we are all pointing one direction (helping somebody with Solar RE).

Of course, we don't have much in the way of humor here--other than the occasional silly posts in a random thread to keep things fun (not always appreciated

).

In the end, I have had multiple comments here in thread and via PM's that most people enjoy the high "signal to noise" ratio here and that there are rarely flaming wars here.

Of course--that is all due to you guys (and gals) that keep on topic (for the most part

).

That leaves time for Niel and I to keep zapping the never ending (so it seems) of spammers and worse that keep dropping by for a "visit" ( :grr ).

In the end, the original poster is the person that sets the direction and tone for each thread... At times, because of request of the OP (or if the discussion is going seriously off topic), I have trimmed the postings into another thread to clean to do a clean-up in isle 35,929.

We are all passionate here--and on occasion--the passion has overflowed a bit.... Such is life.

-Bill

john p · August 2009

Re: Home-Brew vs. Off-the-Shelf

BB please post a comment about my last post.. I like to know what you think of how the seperate "DIY" would work..

BB. · August 2009

Re: Home-Brew vs. Off-the-Shelf

A DIY thread may be started by people who want to share their projects (here is my DIY solar panel, handy electrical circuits, I pulled my inverter apart and I need to find a new xyz FET to get it running again).

And, for threads that start out with a question (I need a high/low voltage controlled switch)--and if it becomes a discussion of different home-built circuits--we can move the thread into a DYI forum...

Mostly--I see the whole "Forum" Structure as a method to also make it easier for us to moderate...

If a DIY forum attracts strong opinions--and everyone is aware of it--then (with our host's approval) that subforum would get "less moderation" (still no flaming allowed--the old "attack the post, not the poster" theme).

Creating a DIY formum, in the end, is really a (for me) a moderation question--and not really content (solar pv, wind, water, etc.)... If people feel that I (and others) are too heavy in our moderation--then this could allow for less.

Post / on topic thread content (detailed electrical discussions over the heads of 90% of us, arguing if there should be a current limiting resistor or not, etc.) was never a question (at least for me). Going beyond the OP's question was becoming an issue as the detailed discussion on circuitry was never in the original post and would be a candidate to moving into the DIY for further discussions.

I was trying not to put too much of my "spin" on the question--I really wanted to hear from you guys and gals. That is why I avoided answering you the first time John. I already know what I think :roll:.

-Bill

icarus · August 2009

Re: Home-Brew vs. Off-the-Shelf

I think we are making mountains out of mole hills here. Does the occasional thread get "highjacked" by the esoterica of learned opinion and indeed differing learned opinion? Sure, but the net result, (as long as no one either gets personal or offended) is that there is useful information imparted.

The reality is many, many OP ask a question and are never heard from again. That leaves it to us to play with idea, show off our knowledge, or waste our own time thinking about elegant solutions to problems that may not even exist in any real world way.

My biggest beef is not with the esoteric answers to seemingly simple questions, but when people get upset with the answers because it is not what they wanted to hear. In most cases those people just disappear which is fine as well. My second beef is people who don't bother to search what has already been written about their question. How many threads do we have that start out with a variation of "I want to power my cabin with 6 lights, a tv/dvd for 6 hours every other weekend?" or possibly even more irksome "I just bought a Harbour Freight 45 watt Pv system and I wanted to power my cabin with 20 light bulbs, a wide screen, microwave, coffee maker etc and now my walmart "deep cycle" battery is dead,, Why?, they said it would power 2500 watts!"

So as a DIYer, I read and try to absorb as much as I can, as most information while it may not be useful now, certainly adds to my data base. I certainly don't consider myself either a Solar Expert nor a Electrical Expert, but by hanging around here for a few years, reading, writing and listening I am a lot close than I was when I started.

You never know when the next answer will hold a gem that might be useful tomorrow.

Just my opinion,

T

nigtomdaw · August 2009

Re: Home-Brew vs. Off-the-Shelf

Icarus that was as close to a rant with out being one,:cool:

nigtomdaw · August 2009

Re: Home-Brew vs. Off-the-Shelf

Why cant I do that:D

BB. · August 2009

Re: Home-Brew vs. Off-the-Shelf

Its OK... We need people who go outside the lines sometimes so we can find out where the lines are.

-Bill

icarus · August 2009

Re: Home-Brew vs. Off-the-Shelf

You want a rant? I'll show you a rant! You can't handle a rant!!!

T

BB. · August 2009

Re: Home-Brew vs. Off-the-Shelf

Oh oh... We hijacked SolarJohn's thread...

-Bill

john p · August 2009

Re: Home-Brew vs. Off-the-Shelf

Come on BB dont be shy let it out for us to read././:cool:[/COLOR].I already know what I think .

BB. · August 2009

Re: Home-Brew vs. Off-the-Shelf

Ok... for the color impaired

:

I am OK with leaving the forums as they are.

A DIY (or other such sub-forum) where moderation is less pronounced will probably just require more moderation in the end (and and I will probably tick more people off too when if/when I do moderate).

On occasion--a thread will go in the ditch and need some help being re-righted... Whether that is a trim of "excess exuberance" in to its own topic--or just a closing of the thread--who knows. Taking each as it comes.

The idea that everyone here is responsible for posting content (in the form of questions and answers) and I don't want to be the one that destroys that setting which has worked so well for so long here.

And, our host, has very specifically said that all on-forum topic (i.e., Solar RE) discussions are welcome. And all discussions of products and industry related issues are to be free, fair, open, and respectful--No moderation for content.

As always, it is dangerous to ask questions you may not know the answer too:

Is the moderation (using a variation of the Goldilocks and the Three Bears):

too heavy
too light
just right

Given that this is a site funded by a business establishment--We really don't get a vote on the subject. This forum is one very visible face of our host.

From my own (limited) experience... Keeping the lid on threads/forums keeps emotions from spinning out of control--And makes moderation easier. We do, sometimes, sneak some jokes, parody, and such into a thread--Sometimes it works (:D) and sometimes if falls flat on its face (

). And then there maybe some cleanup required.

I have seen, very nice family friendly forums, with a "cafe" (off-topic threads--where on topic moderation is less) can have a thread turn into an ugly barn-burners real fast. And, that Cafe has resulted in more rules and more moderation in just one sub-forum (in just a week or two) than has probably been done here in the entire "life" of the Wind-Sun site.

So--I can understand that we will never have an open topic Cafe here--And the level of moderation here will probably continue as is--unless I have been, or will start, messing up here.

In the end, a few basic rules (most regarding spamming, and attempts at "free advertising" / links to Ad/Link Farms) and common sense seems to work pretty well.

Obviously, I am only speaking for myself, not for Niel (our senior moderator) (or WindSun our Admin/Owner here).

End of Blue.

-Bill

john p · August 2009

Re: Home-Brew vs. Off-the-Shelf

ok seems fair to me
im not colour impared .. just blind in one eye and cant see out the other one:D

Photowhit · August 2009

Re: Home-Brew vs. Off-the-Shelf

The reasonable and knowledgable moderation here is one reason I'm here!

I was a regular at another forum, where one of the moderators continually made silly claims, though He appears to be the designer of larger systems and remote relay systems.

When he, as a moderator, claimed "OK you need to know this right up front, an off-grid battery system only has 90% availability vs 99+% of a utility. So off-grid you can expext to be in the dark arouk 35 days in a year on average, vs a day or two with a utiliy."

I protested, then left.

I guess I push the limits a bit, I live in an interesting situation where off grid is a viable option even though there's a power pole 50 feet from my cabin (high user fee and I'm a minimal user)

...and of course in the last 6 years my down time can be measured in hours rather than days.

Now what was the topic?

BB. · August 2009

Re: Home-Brew vs. Off-the-Shelf; DYI subforum/moderations...

Jamming original post in sideways:

Home-Brew vs. Off-the-Shelf; DYI subforum/moderations...

I guess I could always split the sub-theme off in its own thread... :roll:

-Bill "To moderate or not to moderate--that is the question..." B.

n3qik · August 2009

Re: Home-Brew vs. Off-the-Shelf

Ok my 2 cents

I use off the self as much as possible. The thinking is, this system is/will last 20 to 40 years. I am 42, that puts me too old to maintain it when it will need it the most. With the parts I did used, someone else can take care of it. This also is if I should/need to sell the house. The new owners have a good chance to retain the system.

If the system is too custom, in later years, there is an increased chance the new user/owner will just rip it out and sell it for scrap.

With that said, I did write up a users manual for my system.

nigtomdaw · August 2009

Re: Home-Brew vs. Off-the-Shelf

kk let the clever people think for u, I am with that, no offense to not clever people

nigtomdaw · August 2009

Re: Home-Brew vs. Off-the-Shelf

Is this the first post that can never be moderated

anything can be moderated... [moderator]:p

john p · August 2009

Re: Home-Brew vs. Off-the-Shelf

N3QIK Yes that is valid for a complete system. to use bought parts so its easy for the next person to troubleshoot it if something fails. BUT.
Im only guesing here but by reading many of the posts many that come ask questions have bought /been given a few solar parts and looking for something useful to do with them.. IE I was given 1x40w panel and have a attic fan can that be made to work? questions like that
Many more would have systems like mine.not really a full system and absolutely built with no concern for the next person, ITS only 3x80w panels 1x300w inverter to power lights permanently. and a 1000 w inverter for other "on demand" things at various times.. and 4 large "truck " batteries the only thing available wher the hoouse is.As Im not at the house for a lot of the year it has to function with no intervention so had to make a switching device that turns on a battery charger if for any reason the batteries drop below 11v. Now for me I used a voltage switch that I have made many of over 15 yrs. never a failure so why would I want to buy a relatively expensive bought one?
I believe making things gives you a better understanding how things work rather than "just buy something" Throughout the world people modify their cars some with bought bits some home made.
I know there are many people not into making anything. But I think those people miss out on a lot of satisfaction of designing/making something.
Making most parts for a grid tied system is not an option but for other small systems.. yes it is .. Some even make their own panels..
And my 1.45 cents worth I think most systems be at the end of their useful life after 30 yrs. So when you in 70.s its just about all likely to need replacing.
So your manual for the "next" person after you will be the new one you are going to be writing for your new system. But it certainly will have many more features than the one you have now.. most likely things not even thought of now..
30 years ago very few people ever thought we be sitting in front of computers talking to people all over the world..

niel · August 2009

Re: Home-Brew vs. Off-the-Shelf

i thought this was settled in that other thread, but it was allowed to be revived only to see it is dead ending in the same nonsensical arguments.
there is nothing wrong either way that one wants to do something, be it bought or homemade, as long as it will serve its function. even if it should cost more for somebody who would rather build it (usually not the case) there's nothing wrong with it. there is nothing wrong in getting that satisfaction of building either. what one person might do may differ from what another person may do and is up to the individual. functionality and costs should always be considered, but that isn't everything as we know. most people do want the most they can get from something with as little cost with most not being able to do the diy for 1 reason or another.
now, can we start to have agreements or at least agree to disagree and let this go as it is frugal to keep at it this way. if you can't then it too will be locked.

nigtomdaw · August 2009

Re: Home-Brew vs. Off-the-Shelf

doooooOOOOOOoh !18 characters

BB. · August 2009

Re: Home-Brew vs. Off-the-Shelf

Ok--can we let this thread die a natural death if there is nothing to ad--or do we need to euthanize it?

john p · August 2009

Re: Home-Brew vs. Off-the-Shelf

let this thread die..everything possible has been said but start up a forum /thread called DIY strictly for people to talk and discuss DIY. To show circuits. designs of panels ,wind generators.brain surgery machines.. etc etc

Now to keep it on track anyone who has nothing more to add to that forum/thread than "I buy everything" or it "save you nothing" ...[edited]

SolarJohn · August 2009

Re: Home-Brew vs. Off-the-Shelf

BB. wrote: »

T
I have seen extremely well done vector board prototypes/one-offs -- and terrible "commercial" products (some of them looked very nice but had fatal design flaws).
-Bill

This brings up a good point. How much research do you do BEFORE purchasing a product? Are you impressed by the manufacturers website? How thorough is their product documentation? Do they offer tech support? Wiring diagrams and configuration examples (when appropriate)? Then, do you go to forums, such as this one, and read reviews of the product? Is the product reliable, according to those who actually use it?

I've been well pleased with Morningstar and Exeltech products. It follows then that by selecting those, I've not only decided against home-brew, I've also rejected many other commercial products. I have a system that I don't have to mess with (unless I want to). I can depend on it to work well, and not burn down the house when I'm away on a business trip. It's a system that I can depend upon when I need it most, during a grid power outage.

John

Home-Brew vs. Off-the-Shelf

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