120VDC Solar Panel

G'day ignistu,
Ok so your interested in using solar to lower your energy costs, why 120 DC volts????? have you checked out prices for non-grid tie inverters for 120DC volts. I was looking the other night at the doccies on a 48 volt 5kw inverter I'm helping a guy out over here as he has problems and while looking for his model I noticed some 120 DC volt inverters. The smallest one was 10kw and was priced at about 15K. Here in Oz 48 volts is the highest a person can go do thing themselves and any higher DC voltage will require an electrician due to the danger of the high voltage.
Aslo above you quoted 3kw of solar on ebay for $3,000... $1 a watt sheesh at that price either the panels are stolen or aint worth the shipping. I just got some pv panels from China at $5 a watt and they are top quality.

My advise would be just look at a 24/48 volt system, get some batteries and an inverter, charge controller etc and use your power sensibly and just use the grid for heavy loads.

Regards Bryan

I'd agree that 48V is probably your best bet. The advantages of 120V is that it's lower current and will run lots of appliances directly, but this is outweighed by the safety implications and that you'll only be able to buy 120V inverters in <10kW sizes.

It all comes down to size: if this is just for your house then go with 48V, if it's for a huge factory or officie installation then consider 120V.

My initial reason for investigating 120V in the first place was with the thought that I might build my own inverter.

The cells can be bought on eBay and you solder them together yourself. If you do that, the cost is approx. $1/Watt. My understanding is that these are "seconds": Cells that are discarded during assembly, but still put out usable power.

tcmtech said:

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Pirate AE is basically doing it without all the legal and bureaucratic red tape that limits the products out there and drive the prices to the ridiculous numbers that they are now.
That is you build it with what you can get thats cheap and works.
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I'm not big on the term "pirate energy". Piracy is a clearly defined term for criminal stealing of someone else's rightful property. Like if you stole energy from the power company that would be pirate energy.

Building your own *anything* is a moral right of all individuals, provided it doesn't harm others. Someone who contravenes commercial red tape for whatever reason would have to be judged regarding their exact actions and whether those actions DO actually cause harm to others or whether that specific red tape is simply protecting commercial interests of large corporations or making life easier for lazy officials.

Someone who makes their own energy setup is better defined as "independent energy" than "pirate" as they are not stealing something that belongs to others.

As for connecting ANYTHING to the mains grid even if it's just a home made alarm clock someone would be morally obligated to make sure it does not pose a threat to others.

Mr RB said:

I'm not big on the term "pirate energy". Piracy is a clearly defined term for criminal stealing of someone else's rightful property. Like if you stole energy from the power company that would be pirate energy.

Building your own *anything* is a moral right of all individuals, provided it doesn't harm others. Someone who contravenes commercial red tape for whatever reason would have to be judged regarding their exact actions and whether those actions DO actually cause harm to others or whether that specific red tape is simply protecting commercial interests of large corporations or making life easier for lazy officials.

Someone who makes their own energy setup is better defined as "independent energy" than "pirate" as they are not stealing something that belongs to others.

As for connecting ANYTHING to the mains grid even if it's just a home made alarm clock someone would be morally obligated to make sure it does not pose a threat to others.

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I think what you mean to say, instead of "Pirate" is actually something that was popular in older Home Power Magazine articles called "Gorilla Solar".

That's where people would sell electricity back to the grid without going through the hoops the utility wanted or required them to do. They were usually pictured, wearing a bag of something over their head, standing next to their system.

boB

Sorry my mistake on the terminology.
Over all it basically comes down to paperwork and money. Often times the paperwork is what costs all the money.

I am against anyone hooking up dangerous equipment to the utilities however I am not against anyone using the rule and policy makers own rules against them.

I can not legally hard wire my home made grid tie units into my electrical system and neither can anyone else without having gotten permission and having spent a load of money on getting the rules specified for their personal application.
But so far I can just put a welder plug on it and wire up a dedicated outlet and properly sized circuit breaker and then feed back to may local grid.
What you build and where you draw the line in regards to what you are doing being good or bad is a large Grey area.

The legality mongers will point out at every chance they can that anything you build that does not have a certification stamp on it from some bureaucratic safety agency must not be used. Good luck on policing the world and enforcing that one!

Basically what you do on your own property is typically your business just as long as you dont get carried away and draw attention to yourself if you are doing something that can be proven to be dangerous to others.
As with grid tyeing your own home made stuff there are some basic safety requirements that do need to be addressed both for the safety of you, your equipment and anyone else.

Use safety and common sense. Learn your local rules and regulations and then find the loop holes. Give the legality mongers reasons to toss and turn all night and lose sleep over what you are doing! Strangely its very satisfying!

tcmtech said:

Sorry my mistake on the terminology.
Over all it basically comes down to paperwork and money. Often times the paperwork is what costs all the money.

I am against anyone hooking up dangerous equipment to the utilities however I am not against anyone using the rule and policy makers own rules against them.

I can not legally hard wire my home made grid tie units into my electrical system and neither can anyone else without having gotten permission and having spent a load of money on getting the rules specified for their personal application.

But so far I can just put a welder plug on it and wire up a dedicated outlet and properly sized circuit breaker and then feed back to may local grid.

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WITH RESPECT TO THE STATEMENT
But so far I can just put a welder plug on it and wire up a dedicated outlet and properly sized circuit breaker and then feed back to may local grid.

I will not argue you can hook it up and feed power back to the utility. You can do anything you like including bank robbery murder etc - just do not get caught.

I do NOT recommend it for following reasons
1. it is illegal without utility authorization and proper equipment.
2. You can energize the utility distribution in your neighborhood when they trip a line.
3. Doing 2 can kill a lineman or a neighbor who contacts downed line.
4. Doing 2 can blow up your equipment because you overload it
5. Paralleling a source must be done ensuring you are in phase. If not you will damage or blow up your equipment.
6. If your utility catches you they will disconnect without notice and will get real mean and nasty.

This is not for amateurs,
Get help from your utility
I am a generation and power distribution electrician.

Dan Bentler

Do you really think I am dumb enough to run a GTI system without voltage, frequency, and system feed back control loops in place?
And how much power do you honestly think it takes to run a neighbor hood at regular load levels? Let alone with a shorted line on the HV side?

If you honestly new more about how a GTI systems work you would know they are not inverters that free run at 60 cycles AC by themselves. Once the line is disconnected they have no voltage, frequency, or even a wave form to follow. Basically even with out the control loops in place they either stall at DC output or simply shut down if the line signal is not there to tell it what to do. Or at least my designs do!

If your a real linemen you would know that no line worker ever ever just walks up to a supposed dead line and touches it bare handed without properly doing a voltage check followed by purposely connecting a shorting jumper from the common ground line to the actual power conductors. And that jumper is never disconnected until the full repair is done and the line is ready to be re energized.
By the way. My first real job I ever had was a student Co-op job with the coal mines as an electrician. I had full MSHA training on working around live HV up to 23 KV!


The OP was curious and so I gave him the basics.

ignisuti said:

My initial reason for investigating 120V in the first place was with the thought that I might build my own inverter.

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Another reason for using a lower voltage is that you'll get better performance out of a partially shaded array where the panels are in parallel than if they were all in series. Is there a chance that your array will be partially shaded during the day?

Ignisuti go and do some research on home made pv panels before you go waste your money. Plenty of people on the fieldlines forum have made their own and 99.9% of them wish they just bought pv panels as it would of worked out cheaper and better for long term use.
Kchriste is spot on with the series arrangement any bit of shade will drop the voltage to below what you need.

Tcmtech if you want to continue your crap on GTI do it in the thread in AE and leave it there. A few of my online friends have had a look at this forum and they can't believe i haven't deleted everybit of the GTI stuff as in their opinion shonky stuff like that could and probably will endup killing some inexperienced kid trying to do it all on their own.

bryan1 said:

Tcmtech if you want to continue your crap on GTI do it in the thread in AE and leave it there.

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That's not fair, he's just responding to the question asked by the original poster who did raise the subject of GTIs.

A few of my online friends have had a look at this forum and they can't believe i haven't deleted everybit of the GTI stuff as in their opinion shonky stuff like that could and probably will endup killing some inexperienced kid trying to do it all on their own.

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Good on you, I'm glad you haven't deleted it.

In my opinion the moderation here is already nannyish enough, the day it gets that bad that, we can't even talk about doing something potentially dangerous, is the day I leave.

Plenty of people here go on about the hazards of mains, grid tie inverters and HV, if some dumb kid ignores all of that and kills them-self, then they deserve a Darwin award.

Hero999 said:

That's not fair, he's just responding to the question asked by the original poster who did raise the subject of GTIs.


Good on you, I'm glad you haven't deleted it.

In my opinion the moderation here is already nannyish enough, the day it gets that bad that, we can't even talk about doing something potentially dangerous, is the day I leave.

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I couldn't agree more! This should be a place to share knowledge. Yes, please tell me the dangers. Without that knowledge how are we as community going to build something more efficient and safer..?

The danger with GTIs is that if incorrectly designed, it could try to power your whole house when the power is shut-off, leaving everything live.

120VDC is dangerous (although not so much as AC) because, it's continuously live as long as the suns out. Batteries are also dangerous for the same reason. 120VDC isn't too bad because you can easily disconnect the battery/cell banks in the middle, leaving two much less dangerous banks of 60V. If you don't bond the 0V to earth it makes the system safer since it becomes like an isolation transformer, although I still think it's a good idea to connect the 0VDC side to 0V via a high value resistor (1M to 10M) to prevent static build up.

EDIT:
Obviously there's the danger posed by 120V/240VAC.

bryan1 said:

Ignisuti go and do some research on home made pv panels before you go waste your money. Plenty of people on the fieldlines forum have made their own and 99.9% of them wish they just bought pv panels as it would of worked out cheaper and better for long term use.
Kchriste is spot on with the series arrangement any bit of shade will drop the voltage to below what you need.

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I've already gotten part of my panel built from the cheapo eBay stuff. For 1/4 the price, it should have to be a pretty $hity panel for it to not be worth the effort.

But, you're right I haven't yet researched to see what others are saying about them.

I put about 1/4 of the cells together to make an 4.5V panel just for testing purposes so that I could determine the feasibility of my whole project. Had it outside yesterday and tried to take some measurements, but the clouds were out and I blew my meter. Odd that I blew my meter when it was set to 10A. Surely, I couldn't be pulling that much on a cloudy day!?

Been doing some more research. For testing my panels output, I just need to measure the voltage across various resistors and then use P=(V^2)/R, right? Just keep doing that with different resistors until I find the highest power output, right?

bryan1 said:

Plenty of people on the fieldlines forum have made their own and 99.9% of them wish they just bought pv panels as it would of worked out cheaper and better for long term use.

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I wanted to see what other people were saying, but wasn't able to find this forum. Can someone please post a link?

What were you using for a load on the test panel?

blueroomelectronics said:

What were you using for a load on the test panel?

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Changed meter to 10Amp mode used 4 ohm power resistor to measure current. Measured 1.4 amp (still rising) before resistor got too hot to handle, and blew fuse on meter.

The danger with GTI's is that if incorrectly designed, it could try to power your whole house when the power is shut-off, leaving everything live.

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Very true. Same with home made everything else that uses more than a few tens of volts. The design I posted does inherently shut down whenever the grid looses power just by its intentional drive design.
But enough of this. Someone asks a question I will aways answer with what knowledge I can. No fear of reality or potential safety issues on my part.

What the OP is doing is great and I am glad he has an open mind about different possible methods he may be able to explore and he has shown an interest in hearing about safety precautions And I answered the basics of them.
I dont ever recall me ever saying in any thread related to any type of line power level circuit or power source of any ones design not to ever take safety precautions with serious intent.

At least he is willing to try and to do some experimenting with alternative energy. And at a level that can actually power something other than a cell phone charger!

P.S. how many hundred threads here relate to something that can or could be dangerous if done wrong? And who's names are attached to some of them?
If your seriously going to delete threads with potentially dangerous capabilities you had better take a good look at how many there are and be fair about it.
You will have to change this sites title to electro-tech circuits that dont transmit or use energy and run without battery's or power sources. Since thats what will be left.
I am not looking for a fight but you should know by now I dont back down on the safety scare mongering or safety Nazi antics regardless of who instigates it. I always try and present the reality of the supposed dangers as unbiased and truthfully as I can.

And for what its worth I am going to follow this thread since its interesting and I am curious as to what costs and troubles go with doing a full home made non certified solar panel array. And when ever the safety Nazi's pop up I will be there to defend this guys intentions any way I can.

Booga Booga Booga!

Well said TCMTECH!

Another side to consider is that I'm doing this (and probably others) with or without your help. The more help/info you can put out here, the better my odds are of not killing myself in the process!

But, I'm pleading with all moderators listening to NEVER block knowledge of any form.

Has any one really seen how far you would get trying to power back a dead grid with 30 Amps about one minute if your lucky less if your not and then you'll have to reset the power source breakers. Oh you forgot breakers time to look for new power source.