Need suggestion for Grid Tie Inverter for Net Metering (24v solar panels to 120v AC) ~3500 Watts

foolios · June 2016

So far, the best deal I can find is the 3500 Watt Outback Power GVFX3524 Inverter. $1780.00
But it has some extras like battery charging. It seems they all do.
Is there something comparable, without the bells and whistles, that is cheaper?

If not, a question I have is;
If the inverter says it can use battery backup to supplement utility power, does that mean, if I know I don't need some of the stored power; can I push that extra back through the inverter and into the grid as generation?
If that's possible, that may interest me and make it worthwhile to go ahead and get the extras.

Thanks in advance.

solar_dave · June 2016

A Sunny Boy Grid tie is in that realm and no batteries required.
http://www.solar-electric.com/inverters-controllers-accessories/gridtiesolar/sma-sunnyboy-grid-tie-inverters/sma-sunny-boy-standard-inverters.html

foolios · June 2016

Thank you for the response. I mentioned it in the subject title but forgot to mention it again in my post. Sorry about that.
It looks like the Sunnyboy's require over 100V DC. My setup is using 24V. It's tougher than I thought to find what I'm looking for.
I have a feeling that what I am looking for is too cheap for manufacturer's to deal with. The bells and whistles make the cost profitable, I guess. Anyone have any information on 24V Grid Tie Inverters?

foolios · June 2016

I see that the

SMA Sunny Boy SB240 Microinverter For Grid-Tie Solar Systems

has

MPP voltage range / rated input voltage: 23 - 39 VDC / 29.5 VDC

My solar panels are 12V panels in series to make the 24V. Would it possible to use two panels in series with this microinverter?

WaterWheel · June 2016

If you've got enough panels to be worth grid tying why are you limited to 24v? If you wire the panels in series you can bump the voltage up.

foolios · June 2016

I've got 14x12v panels to start. I am going to rethink and look at this again. The Sunnyboy at $1300 is indeed a great deal.

Raj174 · June 2016

This Outback hybrid inverter is grid interactive. It sounds like it would meet your needs. Check it out here:
http://www.solar-electric.com/inverters-controllers-accessories/inverters/ouin/outback-power-renewable-a-series-inverters/outback-power-vfxr3524a-hybrid-inverter.html

solar_dave · June 2016

Normally on a grid tie setup the panels need to be wired in series to allow the Voltages needed for the inverter. My setup has 4 strings of 9 panels each for each inverter. The 4 strings are then joined in a fused combiner box to feed the inverter with a single line.

BB. · June 2016

You also in your title said that you wanted to 120 VAC... Most GT systems drive 240 VDC nominal 208/230/240/etc). Do you need 120 VAC output?

-Bill

foolios · June 2016

Raj174 said:

This Outback hybrid inverter is grid interactive. It sounds like it would meet your needs. Check it out here:
http://www.solar-electric.com/inverters-controllers-accessories/inverters/ouin/outback-power-renewable-a-series-inverters/outback-power-vfxr3524a-hybrid-inverter.html

Thank you, I believe that is the best option for my scenario since I already have an installation in place as a 24v setup w/24v battery bank.The one in the link is thus far the cheapest one I can find. Thanks for the share.

foolios · June 2016

BB. said:

You also in your title said that you wanted to 120 VAC... Most GT systems drive 240 VDC nominal 208/230/240/etc). Do you need 120 VAC output?

-Bill

I have seen that. And it appears that the 240v output versions require that the panels will be mated more in series. My installation has been in place for off-grid for a year now. I am going to try and keep it as simple a changeover as possible.
Plus, I like the low voltage setup on the roof better. Might not be as efficient, but they aren't long runs; using 8 gauge copper; 24v @ ~ 2.5 amps per string.
Thanks for the input. How many manufacturers are there that are UL listed and for 60Hz?
SMA
Outback
Schneider
Fronius
Magnum
SolarEdge
Solis
Enphase

BB. · June 2016

I am not quite sure I understand... Are you bringing the Grid to your, currently, off grid home? Are you trying to take parts of your present off grid system (solar panels, for example) and convert them to GT use with a utility?

There are "interesting" reasons that one can mix GT inverters with off grid and/or Hybrid inverters... But for a pure off grid system, it is usually better just to not use the GT inverter unless you have a specific need to address.

For a grid tied home--Then you have the whole question of how much GT to utility power do you want (to turn your meter backwards/save money on your bill) vs some sort of backup power system (storms, etc.) that you want to protect against (how long of outage, how often of outages, genset vs battery backup, etc.).

-Bill

foolios · June 2016

Yes, sorry about that. This is for a grid tied home. To be placed onto Net metering. I think the suggested Outback GTI is an excellent choice for use with battery. I am still considering whether I want to deal with batteries anymore. But so far, it is the cheaper option to start, since I do have an existing battery setup. But it might actually be cheaper in the long run, without battery, even though the initial cost of inverters without the battery crutch are generally more expensive. If I could find a GTI that will just do the solar conversion/inverting for sellback/use on the grid, that was about the same price. I would like that to do that. Unfortunately, I have only found some in the same ballpark of cost that will require me to rewire my already currently installed panels to meet the higher DC voltage requirements.

BB. · June 2016

GT and OG inverters are similar in pricing ($$/Watt). What drives up costs for Off Grid system is the price (and replacement) of the battery bank.

If your power outages are rare (once or twice a year) and short (less than a day), then a backup genset (propane, gasoline, diesel, etc.) fueled genset is going to be more cost efficient.

If you have lots of outages and/or long outages (week or two long or longer), then keeping your battery bank may be worth while.

Part of the question is "how generator adverse" you are (noise, fumes, fuel handling, etc.). Batteries are just a pain in general.

-Bill

foolios · June 2016

For sure they are getting to be a pain. And then adding distilled water every so often is adding to the cost of upkeep.
I am really rethinking this. It really seems like I should have the array restrung to a higher DC voltage. I'm going to keep looking at GT inverters and keep the OG one I like in the back of my mind. With 14 panels/1.4kw already in place, I may just add the few I need to get to that 200v DC range for going with GT.

Thanks for walking me through the thought process.

BB. · June 2016

Today, 1,400 Watts of solar panels are worth about $1,400 (if new) for a gt system.

You may get about that much if you sell them used into somebody with a smaller off grid system.

For a larger gt system (over 1,400 watts), new panels for a gt inverter is going to be much less headaches, and may cost less too.

-Bill

Need suggestion for Grid Tie Inverter for Net Metering (24v solar panels to 120v AC) ~3500 Watts

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SMA Sunny Boy SB240 Microinverter For Grid-Tie Solar Systems

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