migrating off grid slowly but modularly... need some tips

[solarface]

ok, so i have purchased 4500 watts worth of 6x6 A-grade solar cells at about 30 cents per watt. I know this is a HUGE amount of cells and is likely a lot more than i need but i figured the price was right and i can always resell some of them later. Anyway initially my plans were to use the chinese plug and play grid tie inverters and ive learned this is a big no-no especially considering i have a smart meter... since im going to building my own (aluminum angle for the frame and tempered glass for the front and slygard or equivalent for the encapsulant). I know its much harder next to impossible to get diy panels grid tied, so what i want to do is put some of my appliances on solar, first off i would like to put a 5000 btu window unit on solar, i plan on building out to begin 3 36x6 panels which will equal 180-200 watts per panel... my goal initially is not to be able to power the window unit overnight on battery bank power, merely to power it on solar when the sun is shining, i realize i will still require a battery bank/inverter charger combo to achieve this, basically i was thinking about starting with a pair of 6 volt trojan golf car batteries and i dont know what inverter charger yet, again for now what i want is to reduce the grid power the window unit uses as i want it to use the sun/batteries when the sun is shining and when the battery power reaches 50 if its shady or night time i want it to switch to grid power thus reducing my overall power consumption, the goal is to one day have MUCH of my home off grid and to have a MUCH larger battery bank but for now considering i have very reliable cheap grid power id like to start small and build my way to a cheaper electric bill.... I know a lot will be tempted to respond "sell the cells and buy panels" this may be true, but i can still build these significantly cheaper than i can purchase them per watt and im very handy w/ soldering iron and my hands and i plan on building the panels the right way and not half assed. Please comment or give advice on what ive stated, im not really asking what would be a better idea... although you can offer, please give me comments on the situation with the 5000 btu using solar during the sunny day.

[Bala]

Ok, I will be the first, what you are planning is not going to save you money, as long as you have grid power then forget off grid to save money.

The second will be straight up that you air con project will not work on the size panels you propose,

If you are going to go off grid then you need to get some understanding of how the systems work,

at the top of this off grid section is a sticky post about designing off grid systems, have a look at it, and there are plenty of other websites along the same lines,

work out the power usage from the ac and then what panels and battery set up you will need,

You will need to factor in start up current of the a/c for inverter battery size, over all power usage, what happens if clouds come over????

[solarface]

hmmm

well based on your reply I feel you didn't thoroughly read my post. I clearly stated i don't expect the a/c to run off batteries when sun isn't available or its cloudy... so for your question of what happens when its cloudy.... clearly it would switch to grid power(ie: grid battery charger adds juice to the 2 batteries).... what my goal is to reduce grid usage on this a/c when the sun is shining and to switch back to grid power when the batteries are 60 % i figured this could be achieved by a charging inverter.... you say i wont save money but if the sun is shining and the a/c is running off the solar/battery array when its sunny i dont understand how this isn't saving money i feel like maybe you read i wanted this one a/c off the grid when really i wanted it to be more of a hybrid system that uses the sun when its shining... and my goal was to be able to scale this up and add more batteries and have it running longer off grid power before it switches down the road though. you posted as if i didn't know inverter requirements or start up requirements of the a/c the values are as follows, the a/c runs @ around 500 watts while its running startup is around 1000-1100 watts, so a 2000 watt max 1000 watt running inverter would do the trick...

so basically would i need 4 180-200 watt panels to achieve the goal im wanting and that basically is having the 5000 watt supplemented by solar during the sunny day and switch purely to grid at night.... I am doing to to avoid a huge battery bank startup cost i want to make this modular so i can scale it up as i have enough cells to build 4500 watts worth of panels. i want to start of at a slow pace my goal is not to go off grid not at all i just felt this was more suited to the off grid forum considering im not going grid tie. this would be more hybrid in my opinion

[Sunking]

Solarface you ideas are not going to work. It would be very foolish if you have grid power to go off-grid. What you need to know is it will cost you 10 to 20 times more for electricity for the rest of your life.

[Bala]

you say i wont save money but if the sun is shining and the a/c is running off the solar/battery array when its sunny i dont understand how this isn't saving money

It is commonly accepted by most people that when you have grid power it is not cost effective to buy panels battery inverter etc, it is cheaper to buy power.

Some people do to have a back up for grid outages, but they accept that it is costly.

As for no sun, yes if you have a mains charger that can turn on when a cloud comes over then that may work, but if you are running a minimal battery bank then voltages can drop quickly if a cloud comes over.

A factor on start up current is not only the inverter size, its the battery bank size, if you battery bank is not big enough you can get a voltage drop on start up and that can cause your inverter to cut out on low volts.

[solarface]

let me try to clear this up...

I have purchased 4500 watts of 6x6 polycrystaline A-grade solar cells.. im not going to build them half ass either, i will bus and tab them and encapsulate with eva or something like sylgard with the right glass and alum fram... to start this off i live in arkansas where its hot/sunny most of the time. but to get started i wanted to make a system that used the batteries basically as a capacitor to hold the power the charge controller is taking from my 800 watts of panels i will initially construct. 5000 btu uses 1000-1100 watts start up power and running power is 500-600... my plan was to use 2 - 4 trojan golf cart and a inverter that is 2000 watt max and can handle 1000 constant max... the goal im trying to accomplish is NOT off grid at all but what im trying to accomplish is to accomadate the a/c with a battery bank / solar bank through the sunny parts of the day and if their isnt enough juice (battiers drop to 50-60 percent/ not enough sun) then a grid charger or a plain battery bank to grid switch manual or automatic would occur to put the 5000 btu air conditioner back on grid power until the bank recovers to 100 percent (considering its day and not night, it woudlnt be beneficial to run the a/c on inverter overnight without ample power). the goal i keep reiterating here is that it could be possible with enough panels and a small battery bank to get free a/c with a small battery bank on the SUNNIEST part of the day. and thats the idea im trying to hammer out here, i know its possible, just trying to figure out the best way of doing it... remember i have reliable grid power but i also have 4500 watts of 6x6 solar cells i bought @ 30 cents a piece, unbroken/very good quality, and id like to integrate this a/c to runn almost free during the sunny days.

[russ]

4500 watts of 6x6 solar cells i bought @ 30 cents a piece - the seller said they were 'very good quality'? Good salesman.

You will find your finished panels more expensive - You still have to buy the encapsulating material, frames, diodes etc.

[solarface]

....

i bought multiple kits....


i have 300 x 4 asian pc cells wheich are sealed and unbroken and a grade, i opened one pak to look at and its VERY good, tests in sun show good results some have MINOR like tiny chips on edges, but they are sealed and packed and supposedly untouched....

i have 1000 euro PC cells, uncracked and put out equal volts per testing.... varies 4 - 6.5 watts per cell

so yea... what i got is what they claimed i have nearly 2000 feet of tabbing wire included and about 15 junction boxes with ends on them... so i feel like its worth putting some labor into.... these are all 6x6

[Bala]

the goal i keep reiterating here is that it could be possible with enough panels and a small battery bank to get free a/c with a small battery bank on the SUNNIEST part of the day

get free a/c

You have stated that you need a 500w continuous supply, I have 2200w of panels and a big battery bank, in the middle of summer on a good day I would only expect to run 500w continuous after 10am at the earliest, once the battereis have recharged from the previous night and then only until 3 or maybe 4pm.

I think you will find that if you genuinely calculate the amount of time you are going to be able to run this a/c off solar power for, actual usable sun hours,

then what it costs you to purchase the cells, make the panels, buy the battereis, controller, inverter/charger, cables, breakers etc and factor in battery service life.

The grid power you will use to charge the battereis

Then do the sums, cost of system per year of life + grid power to charge batteries, cost per year = ?? then take off your savings? from solar = you will have a = or - number.

You are asking for free power and it is not possible, I live off grid and it is far from free, you asked for advise on saving money, that is what you are getting

[solarface]

even still as i said i have 4500 watts of cells... im not asking to run grid free im asking to supplement...and if i have to grow my battery bank i will as time passes but i feel like you guys are saying i should go buy some barrels of oil and just burn away and say xxx it to being green or reducing the bills...

[Bala]

not sure why you are getting upset,

You purchased components then asked for opinion on you project, TO SAVE MONEY, and the responses you got are not what you wanted to hear.

I have tried to explain why you will not be saving money, if you dont believe me thats ok, I am just a faceless name on a forum.

your comment about burning oil and being green is a whole different story.

[Sunking]

i feel like you guys are saying i should go buy some barrels of oil and just burn away and say xxx it to being green or reducing the bills...

That is because you are very misinformed.

With a off-grid battery system not only will you never achieve and ROI, you will never obtain EROI. That means it takes more energy to make the system components than the system will ever generate. So in your case you will be paying a lot more money for electricity, and doing a lot more harm to the environment. Battery systems should only be used if there is no other alternative.

[Mike90250]

Best you can do is to sell the cells for what you paid for them.

NOBODY sells prime cells. You have been most likely sold what's called 2nds or floor sweepings. They just look good. Do they have any specs / certs for Reverse leakage ? That's a common, non visible, rejection criteria.

The very best, heat & vacuum laminated home made panels, may last 3-7 years. Locating factory belmish panles on sale is the least expensive way to go, unless you really like repairing homebuilt stuff.

Please, make one panel, and stick it outdoors for 2 years, and see how it fares. One panel won't hurt your bank acccout too much, but I don't have a fancy sales site, or you-rube channel to show panels after 3 years in the weather.

We've got no vested intrest, but woudl rather you know BOTH sides of the issueup front, before you develop plans and spend your $$$ on something that WILL fail much sooner than the folks selling you encapsulant (check the vater VAPOR transmission of your components, most plastics, epoxies, and goop, do not block water vapor.)

Look up Dr. Komps panel construction method, and this stickie post about building panels : http://www.solarpaneltalk.com/showth...ght=fieldlines
and the links in it.

[solarface]

frustrating

whats frustrating is that ive continuously stated i don't want to go off grid, i just wanted to set up panels that supplement power to my 1 window unit using the batteries basically as a capacitor to run the inverter, and it would switch back to grid power if it wasnt and as i expected and asked for you guys to SIMPLY comment on that not really anything else, i have done research and if you'd looked at the market lately you would see you CAN get good cells you just have to know where to look, i asked NOTHING about encapsulation or ANYTHING else you've said, i simply asked how down the road if a a/c is using SOME solar when its super sunny to run on LESS grid power how is this not saving money i feel like thinking outside the box is beyond what you guys are capable of and im not insulting your intelligence i just am frustrated about how the only replies have been about how my batteries aren't enough to go off grid (duh)... that was never the intention... i just wanted to know how feasible it is to run the 5000 btu on solar supplemented by grid when necessary it seems i could consume 20-40 percent less a/c from the grid this way from this one a/c .... remember i want it to switch to grid power wheneever it needs to but i guess i can beat a dead horse and it still wont just reply to the specific situation im talking about instead of telling me why im an idiot for wearing purple shoes.


i thought this was completely the point of a inverter/charger combo that auto-switches to grid power when batteries hit a certain point then back to battery when they are charged from sun or grid.



also i love how how I was misquoted saying i want free ac.... well you left out the part where i said WHEN ITS SUNNY... i get it isnt completely free but damn i didn't realize i was going to be picked a apart i simply presented an idea i haven't read about and was asking about its viability Ive already seen how many people hate on home made panels, how do you know i don't have a vacuum sealer for eva...and no, not a dustvac.......

[Sunking]

i thought this was completely the point of a inverter/charger combo that auto-switches to grid power when batteries hit a certain point then back to battery when they are charged from sun or grid.

No that is not how they work. What you are talking about is a hybrid inverter. When grid power is available it acts like a regular grid tied inverter. Only when the power fails it switches to bateries, then tells your generator to come on and take over until commercial power returns.

When commercial power returns and stabilizes, the inverter switches back to grid tied, generator shuts off., and the batteries are recharged via commercial grid power. So what you think it should do, does not work that way and you would be completely wasting your time and money.

Now here is the fun part. You cannot use DIY panels in your home premisses wiring system in any code compliant manner.