Need help deciding how to do this project a few questions about wiring configuration

[FireMedic356]

Hi i am totally new to this forum and to solar power in general. i have some basic electrical knowledge and a high mechanical ability. so i am looking into making a solar array for my roof top. i am still in the planning phase. i am thinking about using a ul certified aluminum frame and recycled tempered glass out of a high security storm door. i realize i will get energy loss in the glass but it is the only practical solution i can came up with on my budget. and i plan of using a epoxy sealer such as slygard or similar product to encapsulate the cells. let me get some thing out in the open here. i am building this system to be a grid tie system for the sole purpose of reducing my electric bill by 30-60 dollars per month and for the experience of building a system that can save the planet ( lol ) and a small amount of money. i dont have any grand ideas that i am going to go off the grid or that i will save tons of money. but i do expect to be able to build a fairly durable and safe panel for less than i could buy one. with that said if i could find professional panels for the same price as i could build them i would probably just buy them and do the rest of the system myself. 1. so if anyone knows where i can get panels to equal aprox 1kw for 800-900 dollars that i am planning on building my panels with i would be interested and would appriciate any help or suggestions... ok on to the purpose of this post. i am planning on using 3x6 cells and building a panel of aprox 120 cells in a 10 rows x 12 rows configuration ( that is what should fit closely to my glass size that i am using to build the frame around) 2. my question is how do you suggest i wire the cells my ultimate goal is to make the total output at 18v and i am not exactly sure of the watts .. fyi each cell is aprox. 0.5 v and 1.8 watts.. how do you suggest i wire them . i am looking for examples such as wire xx cells in series to make 18 v and wire xx of those 18v groups to make xxx watts . i just cant wrap my head around how to do this right. 3. i am planning on using 4-5 of these panels to get a total output in the neighborhood of 1000watts and running the wires to a junction/ breaker box with individual breakers for each panel, then running to a power monitor and on to a grid tie inverter and i dont know if using a single 2000 or 3000 watt inverter is better or should i use 3-4 inverters wired to individual panels then into the grid any ideas thoughts or suggestions that are constructive and helpful would be really appriciated. i want to make sure i have this whole thing planned out perfectly before i even buy the first componet .. thanks and sorry for the long post there is just so much i want to know before i start..

[Sunking]

OK two issues.

1. You can buy factory UL listed panels cheaper than you can make the.m
2. You cannot use DIY panels in any code compliant way on a grid tied system, or on any system where the wiring is integrated into your premisses wiring system.

[Naptown]

First off you would use 108 cells not 120
next why build a 12V panel for an on grid system you would want higher voltages
Next is what Sunking said above
Let me make a suggestion that will save you a bunch of money in the long run.
Buy some 72 cell modules with UL listing. 230 watt maximum) Yes they will cost a bit more but will outlast whatever you build by a margin of 5-1( lifespan on diy panels is typically 5 years or less.)
Buy some Enphase M190 inverters.
Modules in that size can be had for a little more than a dollar a watt if you look around. The inverters run around $180 each.
Now with your budget you may only have enough for 3 modules and inverters. But it will be a legal system that will be able to connect to the grid and will not void your homeowners insurance. Now you can add on up to a total of 15 modules on the wiring you already have in place as money permits.

[FireMedic356]

ok thanks for the advice... i think

Well until this morning i have been unable to find professional panels that are within 200 dollars of the price that i can make them myself with materials i already have in the barn and recycled materials obtained from a local supplier . and that does not even factor shipping into the picture. some people keep saying you can get brand name panels for less than you can make them but no one ever seems to be able to point me in a direction as to where to find professional ul listed and certified panels that cost less than 90 cents to 1.00 per watt. i do understand that the pro panels are hands down gonna be better constructed and more likely to last for the entire 25-30 years expectancy. whereas the diy panels i was looking into making would be sturdy and dependable but would not last as long undoubtedly. with that said i have found some panels made out of grade B cells manufactured by sharp that come with a full warranty and are ul listed and certified and they only cost about 1.20 per watt as opposed to the .90 cents i was looking at spending to make my own and luckily the seller is based out of a city only 45 min from my home so i can save over 200.00 on freight shipping charges by picking them up myself. so i will probably just buy them and use them as a starting point. they should put me at 896 peak watts and somewhere 36 v open current . so the last part of my question remains .... regarding the grid tie inverter is it better to use 1 large inverter 1500 - 3000 watts that all 4 panels tie together and run into or should i use several smaller 300-500 watt inverters supplied by its own panel after going through breaker box and kill switches. and just to satisfy my curiosity can anyone tell me what the best way to wire the diy cells would have been because i may still end up constructing a few of them to use off grid to power lights and a few shop tools in my barn

[FireMedic356]

thank you

First off you would use 108 cells not 120
next why build a 12V panel for an on grid system you would want higher voltages
Next is what Sunking said above
Let me make a suggestion that will save you a bunch of money in the long run.
Buy some 72 cell modules with UL listing. 230 watt maximum) Yes they will cost a bit more but will outlast whatever you build by a margin of 5-1( lifespan on diy panels is typically 5 years or less.)
Buy some Enphase M190 inverters.
Modules in that size can be had for a little more than a dollar a watt if you look around. The inverters run around $180 each.
Now with your budget you may only have enough for 3 modules and inverters. But it will be a legal system that will be able to connect to the grid and will not void your homeowners insurance. Now you can add on up to a total of 15 modules on the wiring you already have in place as money permits.

i appriciate the helpful advice . like i said i am totally new to all of this and just began pricing materials for diy and searching for assembled name brand panels and have no idea what to even look for. thats why i am here asking for help.. and especially thank you for the inverter advice i can figure most everything else out myself with alittle advice from you guys who know what you are talking about but the inverter issue is something i am totally lost on and def. need all the advice i can get now in the planning phase so i get it all right

[Naptown]

You could use a string inverter in the 1500 watt range but at this size system it would have its disadvantages.
1 string inverters work best when working at or near their peak wattage ( efficiency)
That said you don't want to over size your inverter too much as you will lose effficiency.
The reason I suggested the Enphase is that you can purchase 4 for now at about the same price as a grid inverter of equal size. Should you want to expand your system the easiest way is with the M190 as these will simply plug into each other to a maximum of 15.You should check the compatbility of the modules with the inverters so a model # would be helpful and go to the enphase compatability web page to check that that module will work with the M190.
Actually the M215 is a better inverter with a longer warranty but the trunk cable can get pricey particularly if expanding a system. It would be best to purchase more than you need and cap off the end and plugs ( they make plugs) and coil excess up under the last module than to splice it a bunch of times.

[peakbagger]

In order to do a legal grid tie system you most likely need it done by a licensed electrician or at least inspected to see that it complies with an electrical code. In my area the utility had the option of requiring a DIY owner to have an electrican sign off on the work but they waived it for me (but dont assume if this is an option that they will waive it for you) As for what code, thats up to the state/local inspector as to what is currently adopted for your region. Unless you are an electrican with experience with electrical codes, just picking up a code book wont do. Its not DIY for sure.

A lot of folks dont realize that what they are installing can generate hazardous voltages for 20 plus years so if they use the wrong materials and techniques some unsupecting person could get injured or killed long after the original installer is gone. The code is intended to require the mimimum materials and practices to ensure that the system is safe for the long run. As solar is still the new kid on the block the codes are updated periodically as new information and equipment is learned.

John Wiles who works for the DOE has published a couple of versions of a manual on how to do code compliant installations that is somewhat readable but assumes some electrical background. I found this link quickly but there may be newer versions out there. Do note this link is for a 2005 code, you might have a different and more stringent code.

http://www.altestore.com/howto/Solar-Electric-Power/Installation/National-Electric-Code-and-Solar-Electric-Systems/a45/

If you are DIYing it and your utility will allow a DIY installation, your best shot is to buy a integrated system of AC inverters and wiring that some manufacturer determined is code compliant. Currently the system I am aware of is Enphase microinverters that appear to be close to plug and play as long as your new panels will work with them. The dollars per watt is probably higher than a single inverter but for a small size system that might be expanded in the future, they may be the ticket for you. Does this mean that there arent other systems out there, NO, but that is the one that I have reviewed for a possible future installation and it looked a a lot more complete than other systems. Do note even Enphase will require some checking to make sure the main breaker panel is of adequate capacity to accept PV and taking into account any local utility requirements. Some utilitys require outside locable disconnects and some dont.

For small systems that are done mostly for learning, there is a lot to be said to doing a battery based off grid system with a inverter to power equipment directly. There are still hazardous voltages and currents but the odds are you will only zap yourself and the system will not be in exisitence for a long time.

[FireMedic356]

thank you for the good info and the resources. i like the enphase m 190 inverters thank you. i had originally planned on running dc power into a traditional grid tie inverter so that is why i was wondering if i should use smaller inverters or one large inverter. it looks like the traditional inverter(s) is more economic in the short term but the enphase is the better option for expansion . and i honestly would like to expand the system as my budget allows i just dont know when that will be. and as for having an electrician do the work or having it inspected i have a friend who is an industrial electrician who has offered to help me install whatever system i choose to make sure everything is done safely and to code. i just am trying to figure out how to get the most bang for my buck right now with a grid tie system and do some experimenting with off grid system and sine inverter for my barn. it only has a security light and a few florescent banks that i turn on when i am working in there and occasionally i use a bench grinder or a power drill. or small air compressor . but that is all just as time and money allow me to play i am mostly worried about the grid tie system for the house right now. so keep the suggestions and advice coming i appriciate all of it.