Solar Panel, Inverter and Large UPS's - Offgrid system help pls

[fastfwd]

Just doing some more digging...

found this site on the forum http://pvwatts.nrel.gov/pvwatts.php - a 1.5kw solar system such as the one i have acquired supports a maximum of 7.8kWh max in summer and a 3.9kWh minimum in winter at my address. I have 175watts of usage i want to power off grid which adds up to 4.2kWh per day.

So really i am on the money with the solar setup i have for the power i want to support, i just need storage that can support the same. Where can i look for a solution for this and what coin am i looking at spending to provide such a solution? at 26c a unit in Australia the cost comes to roughly $700 in savings per year. Will the batteries for this cost more than $700. If it can pay itself off in one year that would be ideal.

[Sunking]

Just doing some more digging...

found this site on the forum http://pvwatts.nrel.gov/pvwatts.php - a 1.5kw solar system such as the one i have acquired supports a maximum of 7.8kWh max in summer and a 3.9kWh minimum in winter at my address. I have 175watts of usage i want to power off grid which adds up to 4.2kWh per day.

So really i am on the money with the solar setup i have for the power i want to support, i just need storage that can support the same. Where can i look for a solution for this and what coin am i looking at spending to provide such a solution? at 26c a unit in Australia the cost comes to roughly $700 in savings per year. Will the batteries for this cost more than $700. If it can pay itself off in one year that would be ideal.

You have done so many things wrong, it is hard to decide where to start.

So let's start on Pay Back. It is impossible to ever acheive payback on an Off-Grid System. Anything you take off-grid will cost you 4 to 6 times more than buying it from the POCO the rest of your life. So if you are considering doing this to save money, then you are delusional. Never going to happen

Second blunder down under you made is sizing your battery to be fully discharged every day. If you do that, your batteries will be dead in less than a year. Minimum battery size for a system to be cycled daily is 5 times the capacity you use in a day which gives you 3 days of clouds to CYA and to maximize battery cycle life. Emergency system size is 2 days. So you have estimated $700 is delusional, more like $3500 to get the most bang for your buck. If you buy a top of the line battery, only discharge 20% per day, you might get 5 years out them before needing replaced. However that takes a lot of Tender Loving Care to get 5 years. At 4.2 Kwh per day requires a 12 volt 1750 AH weighing in around 1300 pounds and costing around $4000 for a 5 year battery

Lastly no place on earth gets 12 Sun Hours. When you looked at PV watts, you inputted garbage and got garbage out. Efficiency assumption in PV watts is 80% for a Grid Tied System. You did not change that to 66% if using a MPPT controller, or 50% if you use PWM Controller. So everything you got from PV Watts is garbage because you input garbage. In a off-grid solar system you have to use the worse case month of the year. You cannot use average or peak. If you use say Average, you go dark in short months. So adjusting and accounting for your eror in winter you receive 3.25 Sun Hours in winter. I have no clue where you came up with 12 Sun Hours, but that is Horse Feathers and Fairy Tales. So at best your 1500 watt solar panel can only generate [1500 watts x 3.25 hours] x .66 efficieny factor = 3.2 Kwh of usable energy per day. Good news is with only 3.2 Kwh only requires a 12 volt 1330 AH, 1000 pound, $3200 battery. If you could get a full 5 years out of your 1st of batteries (impossible for a newb) battery coast alone and nothing else will cost you $0.542 per Kwh USD or $0.75 per Kwh Australia Dollars. So your 26c Australian just went down under the tubes. YOU WILL BE PAYING 3 times as much for power vs buying it jus tin battery cost alone.

[Sunking]

lets say i ditch the idea of using my UPS's as battery banks as it does seem a little difficult for what i will get out of it. Going forward with my 6 x 255watt panels(1500watt total) providing they work (having them tested today). What would i need for an offgrid system to be equal to the amount of power my solar setup will generate? Example: batteries, charge controller etc. Looking to run a minimum of 4.2kWh/day to a maximum of how much the 1500watt solar panels and battery bank can take.

I'm happy to spend a bit of money providing its going to save equal to the same ammount or more over a few years. Here in Aus the price of power is ludicris at roughly 26c per unit.

Simple there is no possible way you can get 4.2 Kwh/day usable with 1500 panels in your location. Only way to get to 4.2 Kwh per day with only 3.25 Sun Hours is if you use 2000 watts of panels. running a 24 volt battery @ 875 AH, with a 80 amp MPPT controller.

[Living Large]

lets say i ditch the idea of using my UPS's as battery banks as it does seem a little difficult for what i will get out of it. Going forward with my 6 x 255watt panels(1500watt total) providing they work (having them tested today). What would i need for an offgrid system to be equal to the amount of power my solar setup will generate? Example: batteries, charge controller etc. Looking to run a minimum of 4.2kWh/day to a maximum of how much the 1500watt solar panels and battery bank can take.

I'm happy to spend a bit of money providing its going to save equal to the same ammount or more over a few years. Here in Aus the price of power is ludicris at roughly 26c per unit.

Your question appears to be, can an off-grid system be built and maintained for less than 365*4.2*0.26 = $400 a year? Your panels wear out after 20 or 25 years, inverter, CC etc 10 years. Batteries? Let's say 4 years though the varies a lot. Will you need a backup (generator) for topping off and cloudy weather?

Do the math. I do not think you can come close to beating the POCO, even at $.26/kwh. And what is the cost of parenting this beast? Immeasurable.

[Sunking]

Do the math. I do not think you can come close to beating the POCO, even at $.26/kwh. And what is the cost of parenting this beast? Immeasurable.

That 26-cents is Down Under Dollars, Convert that to USD is 19-cents. LOL

[Living Large]

That 26-cents is Down Under Dollars, Convert that to USD is 19-cents. LOL

Oh, I didn't see that. I found a 4 year old link that compares costs between numerous countries in US $, and from what I found I assumed the $.26 was USD. Yes, at 0.19, LOL.

[solar pete]

Well I dont know,... what old mate fastfwd is paying sounds like .26 cents AU, over here in little old Adelaide I pay between .26 cents to .40 cents, thats cause our moron gumbyment sold our electricty network (that was already bought and paid for from tax payer dollars) to a Singapore billionaire and agreed to make up new laws for him guaranteeing he make at least 10% a year on his money, HOW THE HELL DOES THAT WORK, ok rant over, go solar

[fastfwd]

Well I dont know,... what old mate fastfwd is paying sounds like .26 cents AU, over here in little old Adelaide I pay between .26 cents to .40 cents, thats cause our moron gumbyment sold our electricty network (that was already bought and paid for from tax payer dollars) to a Singapore billionaire and agreed to make up new laws for him guaranteeing he make at least 10% a year on his money, HOW THE HELL DOES THAT WORK, ok rant over, go solar

pete you being from Aus also and having a similar system to what i have in perth. You think im better of just using as much of that solar gear as i can and get a qualified solar installer to install it as a normal solar solution attached to the grid like any other house in aus? I think 1.5KW systems here are around $1500-2200 AUD installed. I believe 1 of the 6 panels i have that is smashed needs replacing but the rest have been tested working perfectly. The inverter that i have is a 2800Watt (3000watt DC). Being that i only have 5 x 255watt panels that are working fine i have roughly 1250watts total of panels atm. I could use all of that equiptment...buy another 5 panels on top and have a 2.5kw system for half the price?

you think this might be a much better idea?

[solar pete]

Yep, I think if I were in your shoes I would take the 5 best panels and see if you can get some more exactly the same, (you generally need at least 6 panels to get minimum voltage on a string).....you may find that a wholesaler around the place might have a few more and do the grid tied, it will be easier and cheaper than trying to incorporate those batteries as they just are no good for daily cycling What was the brand of the panel again, I can ask the boys if we have any in the warehouse, cheers

[inetdog]

Hello fastfwd,

The image hosting site that you have chosen, postimg.org, is throwing random ads onto the full page views of your images. Ads I can tolerate, but some of the ads they are using are misleading at best and malicious at worst. Please try to find a different hosting site, as we may be forced to delete all of your image links. Still deliberating that.

inetdog, Moderator.