# invertor/charger/grid-tie box options



## ET1 SS (Oct 22, 2005)

We have a pallet of solar panels. We got them and ran out of cash, so now we are waiting to save up more cash for the next step. We have the capability of producing 4400watts at 48 volts.

Looking at invertor/charger/grid-tie boxes, it seems that they give preference to the grid. Meaning that your home only runs on solar power when the grid goes down.

We were thinking that we want our home to be solar-powered most of the time, with the ability to draw utility power only to help keep the batteries charged like when it is snowing.

We are not concerned with feeding power to the grid.

We live in an area where the grid goes down at least once each month. Which makes it difficult to run incubators and such.

What are your inputs?


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## TnAndy (Sep 15, 2005)

ET1 SS said:


> We have a pallet of solar panels. We got them and ran out of cash, so now we are waiting to save up more cash for the next step. We have the capability of producing 4400watts at 48 volts.


What are the exact spec on the panels.....watts per panel, number of panels, etc. 





ET1 SS said:


> Looking at invertor/charger/grid-tie boxes, it seems that they give preference to the grid. Meaning that your home only runs on solar power when the grid goes down.


Not really. 

Your home runs on whatever power is produced when it's produced during the day.....meaning the only time your grid meter will stand still ( or turns backwards in our case.....meter is bi-directional ) is IF your solar is producing more than the house is using....and I can set the "sell" point on the inverters to where the batteries to drain them at night IF I wanted, but that would be foolish since that would cycle the batteries far more than necessary ( like living off grid ), causing me to have to replace them more frequently, ( batteries have a certain number of discharge cycles and then it's over for that set ), and WHY the heck do that when grid power is so cheap ?? Battery back up means BACK UP. I've got grid power here right now at 9 cents/kwhr......WHY would I want to replace it with 50 cents/kwhr power ???? ( that's a guesstimate based on battery replacement every few years versus more like 20-25 years with the set of AGM batteries I have )




ET1 SS said:


> We were thinking that we want our home to be solar-powered most of the time, with the ability to draw utility power only to help keep the batteries charged like when it is snowing.


Yep....you CAN do that.....simply program your inverter set points to do as you want.....but as I said, it doesn't make economic sense to do so.



ET1 SS said:


> We live in an area where the grid goes down at least once each month. Which makes it difficult to run incubators and such.


What you need is a grid tied battery backup type system with an automatic transfer switch ( mine is manual.....because it's a lot cheaper....I have to walk out to the garage and flip it when the grid goes down ), which will make it nearly seamless when the grid goes down. ( just few seconds of outage....enough to where you'd have to reset all your clocks....ahahahaha)



ET1 SS said:


> What are your inputs ?


Re-think this.


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## ET1 SS (Oct 22, 2005)

TnAndy said:


> What are the exact spec on the panels.....watts per panel, number of panels, etc.


220watts each, 20 of them.





> ... Your home runs on whatever power is produced when it's produced during the day ..... meaning the only time your grid meter will stand still ( or turns backwards in our case ..... meter is bi-directional ) is IF your solar is producing more than the house is using .... and I can set the "sell" point on the inverters to where the batteries to drain them at night IF I wanted, but that would be foolish since that would cycle the batteries far more than necessary ( like living off grid ), causing me to have to replace them more frequently, ( batteries have a certain number of discharge cycles and then it's over for that set ), and WHY the heck do that when grid power is so cheap ??


When looking at ads for invertor/charger/grid-tie boxes I am not seeing adjustable set-points.

When I have spoken with locals who have tried to be grid-tied, the bidirectional costs higher monthly fees to have, and any power 'sold' to the grid is charged additional taxes and fees. They do not break even.

Their advice has been to either sever the grid connection entirely, or else use a manual cut-off and only plan to manually select the grid should there be some 'need' for it [but only when the grid is up].


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## wy_white_wolf (Oct 14, 2004)

ET1 SS said:


> .... Meaning that your home only runs on solar power when the grid goes down....


Not really.

Your home will use power from solar porviding the PV system is producing. If it is producing more than you use then the excess goes to the grid. If you use more than it produces it will make-up the excess from the grid.

I think what confusses most on this is that the batteries are only used when the grid goes down. That is actually preferable as they will last longer because of less cycling and will always be fully charged when the grid goes down. I could think of nothing worse than having a battery backup system that the batteries were already discarged when the grid went down.

By specs I think TnAndy was looking for the VOC, VMP, and IMP of the panels.

WWW


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## ET1 SS (Oct 22, 2005)

wy_white_wolf said:


> Not really.
> 
> Your home will use power from solar porviding the PV system is producing. If it is producing more than you use then the excess goes to the grid. If you use more than it produces it will make-up the excess from the grid.
> 
> ...


Ooops my bad, sorry.

These panels are 'Evergreen ES-E 220W' 

STC Power Rating 220W
PTC Power Rating 196.5W 1
STC Power per unit of area 12.5W/ft2 (134.3W/m2)
Peak Efficiency 13.43%
Power Tolerances 0%/+2%
Number of Cells 120
Imp 7.54A
Vmp 29.2V
Isc 8.22A
Voc 35.9V
NOCT 45.4Â°C
Temp. Coefficient of Power -0.43%/C
Temp. Coefficient of Voltage -0.111V/C
Series Fuse Rating 15A
Maximum System Voltage 600V

Type Polycrystalline Silicon
Output Terminal Type Multicontact Connector Type 4
Frame Color Black
Length 1,722.5mm (67.8in)
Width 951.3mm (37.5in)
Depth 46mm (1.8in)
Weight 19.5kg (42.9lb)

80% Power Output Warranty Period 12yrs
90% Power Output Warranty Period 25yrs
Workmanship Warranty Period 10yrs
CSI Listed Yes


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## TnAndy (Sep 15, 2005)

ET1 SS said:


> When looking at ads for invertor/charger/grid-tie boxes I am not seeing adjustable set-points.


You won't see it in the ads.....you'll have to dig down DEEP in the manuals to find it, and I can't speak to any brand but Outback......but with Outback, you can set all kinds of things to about any point you want......assuming you can negotiate the fool menu system they use.....personally, I call their tech support line, tell 'em what I want to do and let them walk me thru it.... :grin:

Any inverter you're considering, download the PDF of the manual for it, and study up on what you can and can't do.





ET1 SS said:


> When I have spoken with locals who have tried to be grid-tied, the bidirectional costs higher monthly fees to have, and any power 'sold' to the grid is charged additional taxes and fees. They do not break even.


I don't see how they can tax YOU on power you're selling to them, but yeah, fees/costs for special metering you can get stuck with. Every utility around the country does solar infeed different, some are very receptive, some simply don't want anything to do with it. I'm fortunate to live where TVA (Tennessee Valley Authority ) is BIG on solar, and offers a 10 year buyback at 12 cents OVER retail.....so by producing about 1/2 our needs, we have no bill.....and since we produce about 3/4, we actually get about 400-500 bucks/yr back at the end of the year.

But without that program, we wouldn't "break even" either......but so what ? 

Isn't a 30% or 50% or 75% reduction in your bill worth something ??




ET1 SS said:


> Their advice has been to either sever the grid connection entirely, or else use a manual cut-off and only plan to manually select the grid should there be some 'need' for it [but only when the grid is up].


I'd have to see the numbers, but I can't believe they work....off grid power is simply DANG expensive. The only reason I can see for being off grid all the time is if: A: Cost to get power to the home is prohibitive B: You can't get it at all at ANY price. The grid is such a bargain it's foolish (IMHO) to simply be obstinate and choose to be off grid with it available.

That said, I've ALSO been called stupid for putting a battery backup type system in, versus a straight grid tie only system ( which is far cheaper, and more efficient in terms of sell back ).....but the whole reason I put the system in had nothing to do with payback......I'd have done it with NO payback or tax credits. I put mine in so if TSHTF, I'd have a shot at some lights and refrigeration, and not be sitting in the dark like the rest of the country will be when their fuel runs out for their generators. I'm personally of the belief our electric grid is wide open to computer attacks, EMP, solar flares and so on.....and no, my system may not survive all the possible things that could take down the national grids, but at least I'll have a shot at some power. I was born in the 20th century, grew up with electric power, and am sorta fond of it.....ahahahaaaa

You put a real pencil to it before listening to "what folks say", unless your power needs are going to be VERY VERY minimal ( like couple hundred kw/hrs/month or less)



On your panels, I was just curious as to the 4400w @ 48v.

What you really have is about 4000w @ 30v.

I can't say what that will do for you where you live, but here in TN, a 5950w system on single axis trackers ( deduct about 20% for fixed mount right off the get-go ) produces about 500-550kw/hrs/month average. Winter low around 450, spring/fall highs around 650.

If you had a fixed mount 4kw system HERE, I think you'd be doing about 300-350kw/hrs/month average. That AIN'T a huge amount of power to run a "typical" modern house ( National average is 900kw/hrs/month )......so you need to recognize that in advance too.

Good luck with your project, and keep studying !


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## ET1 SS (Oct 22, 2005)

TnAndy said:


> You won't see it in the ads.....you'll have to dig down DEEP in the manuals to find it, and I can't speak to any brand but Outback......but with Outback, you can set all kinds of things to about any point you want......assuming you can negotiate the fool menu system they use.....personally, I call their tech support line, tell 'em what I want to do and let them walk me thru it.... :grin:
> 
> Any inverter you're considering, download the PDF of the manual for it, and study up on what you can and can't do.


Thanks







> ... I don't see how they can tax YOU on power you're selling to them, but yeah, fees/costs for special metering you can get stuck with. Every utility around the country does solar infeed different, some are very receptive, some simply don't want anything to do with it. I'm fortunate to live where TVA (Tennessee Valley Authority ) is BIG on solar, and offers a 10 year buyback at 12 cents OVER retail.....so by producing about 1/2 our needs, we have no bill.....and since we produce about 3/4, we actually get about 400-500 bucks/yr back at the end of the year.
> 
> But without that program, we wouldn't "break even" either......but so what ?
> 
> Isn't a 30% or 50% or 75% reduction in your bill worth something ??


Yes, any reduction is 'worth it'.

We loose power so frequently, that it is a major pain for us.

Two to twelve hours each month is not unusual. Plus stormy weather on top of that, when you can loose power for a week at a time.

We need to shift to something else.





> ... I'd have to see the numbers, but I can't believe they work....off grid power is simply DANG expensive. The only reason I can see for being off grid all the time is if: A: Cost to get power to the home is prohibitive B: You can't get it at all at ANY price. The grid is such a bargain it's foolish (IMHO) to simply be obstinate and choose to be off grid with it available.


In this region we see a lot of homesteaders who simply do not have utility power closely available. Bringing power out to their property can quickly exceed the cost of the property.

When I was shopping for land, it was a common theme.

In our township, we have three families who currently produce their own power. All three use combinations of wind and solar.

One of them is far enough removed that no power lines are available to them. So they are 100% off-grid.

The other two families are grid-tied. But neither sell power back to the utility.

I think they both use utility power to charge their battery-banks. One I see fires up his diesel generator most days for a few hours [he is a welder by profession]. He lights off his gen whenever he is welding. I do not fully understand why he prefers to use his generator-power for welding, rather than Utility-power.





> ... That said, I've ALSO been called stupid for putting a battery backup type system in, versus a straight grid tie only system ( which is far cheaper, and more efficient in terms of sell back ).....but the whole reason I put the system in had nothing to do with payback......I'd have done it with NO payback or tax credits.


We want to cut back on how much we pay to Municipal Utility; and on how much we must rely on them. They are not reliable.

We have no intent to use any tax credits.





> ... I put mine in so if TSHTF, I'd have a shot at some lights and refrigeration, and not be sitting in the dark like the rest of the country will be when their fuel runs out for their generators. I'm personally of the belief our electric grid is wide open to computer attacks, EMP, solar flares and so on.....and no, my system may not survive all the possible things that could take down the national grids, but at least I'll have a shot at some power. I was born in the 20th century, grew up with electric power, and am sorta fond of it.....ahahahaaaa
> 
> You put a real pencil to it before listening to "what folks say", unless your power needs are going to be VERY VERY minimal ( like couple hundred kw/hrs/month or less)
> 
> ...


Thanks


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## Jim-mi (May 15, 2002)

TnAndy is very fortunate to have a friendly utility Co. to deal with.
Yes there is a very large number of utility's who want nothing to do with us who generate power. One of the obstacles that my local uti demanded was 2 million liability homeowners insurance. That was darnded expensive . . If you could even get/find it.
Never mind that my inverter was/is UL approved . . . .meaning that in a feed the grid setting the inverter would drop "feeding" in a micro second when/if the grid went down..
So that would be at least an hour -before- Johnny Lineman would be any where near reparing the 'lines' in my area . . . . . .but the uti doesn't like my kind (home generating) so they put up obstacles to discourage grid tie.
I gave up trying to fight the uti and I am doing what your talking about.
If there is no wind or sun I can flip a transfer switch and run off the grid.....
But the majority of the time I'm running off my battery bank ....
Winter time I use excess energy for electric heat.
Summer time excess energy runs a air conditioner....
And a home built charger allows me to hit or trickle charge ( variable currant) the bat bank from the grid.
Yes it is more expensive than just knuckling down to the grid. . . . .
But my lights don't go out --unless---I turn them off.
Also the uti rates are increasing constantly.
And in these troubled times the possibility of the grid going down for a very long time are very real.............................

A Outback inverter and a good battery bank and your on your way..........


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## nadja (May 22, 2011)

And if I may add to this, you also will need an outback charge controller Try an mppt80


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