Finally, the start of my 25kw Ground Mount grid-tie system

[live4soccer7]

I would imagine the glass on the back would have to be tough as well, but I'm sure it isn't quite as tough so they can cut costs and it isn't subjected to hail.

Where my lines were buried is pretty much 24"+

 

[live4soccer7]

Alright everyone. I'd like some opinions on panels here. I'm pretty much at 3 different panels

Hyundai Bifacial 450W + underside wattage for $220 (local)
Trina 415W for $189 + freight. Probably close to $200 a panel with shipping (texas, the powerstore)
Blue Sun Solar Panels 455W for $182 Plus freight. probably $190-200 a panel with shipping

Price isn't everything, so please throw out some opinions.

 

[live4soccer7]

Bluesun is out. With freight it is basically the same cost as CED's Hyundai bifacial panels.

The trina and hyundai's are close enough to call the same price/watt and that doesn't include any benefic from the bifacial aspect of the hyundai panels.

I think that kind of resolved itself. Hyundai panels it is unless I find a major downside to install or having bifacial panels.

Alrighty, next major aspect is the inverter.

SOLIS is cheapest BY FAR - Frequency-Watts?

Fronius (Frequency-watts?), probably the best choice based on size of the system. I was thinking of doing 3 fronius units and then doing 6 strings that are a little undersized. Use MPPT for each string. This way if I ever wanted to add on to the array then I could. I doubt I will. I'd definitely want to make sure I stay within the optimal string size though. With 5 strings, by dropping 2-3 panels off each string I could make up another string. This would also leave a little headroom in the event there was some crazy cold days that hit that were record breaking and thus increasing voltage. It may also extend the life of the inverter by not running it at 100% capacity as well.

SMA Sunny Boy - Frequency-watts? - a good option, but I think it's too small (7.7kw max) for the system I'd like to build 33-40kw or so. It does have the SPS feature, but as someone mentioned you can simply run a little honda 2k genny for those pinches.

Sol-Ark - They make a nice hybrid inverter. This was suggested by the guy at CED greentech. I'd have to double check on sizing and price.

 

[Hedges]

I forget if I asked whether you have 3-phase or split phase.
If 3-phase there are SMA grid-tie inverters in that wattage range.
Those can be paired with Sunny Island for 3-phase off-grid or grid-backup, but pass-through for grid-backup would be limited to about 20kW. Off-grid, could manage 40kW.

NEW SMA Sunny Tripower CORE1 50kW Grid tie Inverter STP50-US-41 with Dents | eBay

Find many great new & used options and get the best deals for NEW SMA Sunny Tripower CORE1 50kW Grid tie Inverter STP50-US-41 with Dents at the best online prices at eBay! Free shipping for many products!

www.ebay.com

 

[MurphyGuy]

Bluesun is out. With freight it is basically the same cost as CED's Hyundai bifacial panels.

The trina and hyundai's are close enough to call the same price/watt and that doesn't include any benefic from the bifacial aspect of the hyundai panels.

I think that kind of resolved itself. Hyundai panels it is unless I find a major downside to install or having bifacial panels.

Alrighty, next major aspect is the inverter.

SOLIS is cheapest BY FAR - Frequency-Watts?

Fronius (Frequency-watts?), probably the best choice based on size of the system. I was thinking of doing 3 fronius units and then doing 6 strings that are a little undersized. Use MPPT for each string. This way if I ever wanted to add on to the array then I could. I doubt I will. I'd definitely want to make sure I stay within the optimal string size though. With 5 strings, by dropping 2-3 panels off each string I could make up another string. This would also leave a little headroom in the event there was some crazy cold days that hit that were record breaking and thus increasing voltage. It may also extend the life of the inverter by not running it at 100% capacity as well.

SMA Sunny Boy - Frequency-watts? - a good option, but I think it's too small (7.7kw max) for the system I'd like to build 33-40kw or so. It does have the SPS feature, but as someone mentioned you can simply run a little honda 2k genny for those pinches.

Sol-Ark - They make a nice hybrid inverter. This was suggested by the guy at CED greentech. I'd have to double check on sizing and price.

I would stick with SMA.
I would avoid Sol-Ark = Chinese

Fronius does look like a better fit wattage wise as some of their inverters can push a lot of power.. Renvu has SMA SunnyBoy 7.7's on sale for 18 cents a watt while the price I was seeing for the Fronius is up around 28 cents. That's a big increase. Might be beneficial to have multiple inverters that would provide redundancy..
Not sure about Fronius, but the SMA's have an off-grid feature that provides 120 volts at 2000 watts to a special circuit.

I was surprised to find that the big Fronius inverter has a narrow MPP voltage range of 320 to 480. That's pretty tight and could limit your design considerations. SMA has a huge MPP voltage range from 100 to 550 volts allowing far more flexibility.

The Fronius has only two MPPT inputs where the SMA SunnyBoy has 3, and they can operate at a higher voltage.

You want to kind of make sure you match your panels to the MPPT input specs..

Where are you finding 450 watt Hyundai panels? I can't find a listing for them anywhere. That said, the Fronius inverter has only 2 MPPT inputs for up to 30 amps each.. with most 400+ watt panels pushing 10 amps, that means you'll need to parallel panels, which will also require you to install combiner boxes, breakers, etc.. all adding extra complexity and cost to the system.

All my equipment is SMA, both the grid tie and the off grid.. It runs flawlessly and reliably... I can't speak about Fronius other than the tech specs I'm reading, but I'm really glad I went with SMA..

 

[wattmatters]

That said, the Fronius inverter has only 2 MPPT inputs for up to 30 amps each.. with most 400+ watt panels pushing 10 amps, that means you'll need to parallel panels, which will also require you to install combiner boxes, breakers, etc.. all adding extra complexity and cost to the system.

There's no need to use a combiner box to parallel 2 strings into a Fronius MPPT. The current limits vary, MPPT 1 is 30A, MPPT 2 is 18A.

Fronius are top quality kit. #1 rated string inverter for grid-tied application in Australia.

I was surprised to find that the big Fronius inverter has a narrow MPP voltage range of 320 to 480.

Which Fronius inverter are you looking at? 480V is the upper end of the MPPT operating range for their smaller inverters, 8kW and less.

The 15kW Primo MPPT range is 320-800V with a max input voltage of 1000V. ~600V is the sweet spot.

https://d3g1qce46u5dao.cloudfront.net/data_sheet/fronius_primo_3_8kw___15kw_datasheet__us_version_.pdf

Not sure about Fronius, but the SMA's have an off-grid feature that provides 120 volts at 2000 watts to a special circuit.

The new Fronius Gen24 models have this feature, a 3kW backup outlet powered by solar PV, no battery required. But I don't think Fronius are offering these models in the USA yet.

 

[MurphyGuy]

There's no need to use a combiner box to parallel 2 strings into a Fronius MPPT. The current limits vary, MPPT 1 is 30A, MPPT 2 is 18A.

Fronius are top quality kit. #1 rated string inverter for grid-tied application in Australia.


Which Fronius inverter are you looking at? 480V is the upper end of the MPPT operating range for their smaller inverters, 8kW and less.

The 15kW Primo MPPT range is 320-800V with a max input voltage of 1000V. ~600V is the sweet spot.

https://d3g1qce46u5dao.cloudfront.net/data_sheet/fronius_primo_3_8kw___15kw_datasheet__us_version_.pdf

The new Fronius Gen24 models have this feature, a 3kW backup outlet powered by solar PV, no battery required. But I don't think Fronius are offering these models in the USA yet.

I was looking at the tech specs on the renvu.com website and they have them listed wrong on the sales page.. but the tech specs PDF link does confirm what you just said about the input voltage.
Thanks for the correction!

I like renvu, bought all my stuff from them and got great service, I should alert them to the error.

 

[live4soccer7]

Unfortunately, I do not have 3 phase. I need to digest the information you guys just posted. Thanks. As always, very valuable.

Surprisingly, bluesun dropped their price when I told them I would not be purchasing the panels from them. In fact, I have been able to find better prices on everything. They dropped the price on the panels to $195 delivered. That puts the 455w panels at about $.42-43/w and the other panels around $.48-.49/w.

The hyundai panels are from CEDgreentech. I'm guessing they're getting a container in. They'll have them available in 1.5-2months, which works well for my timeframe since I'm still working on design, applications, permitting.

 

[live4soccer7]

@MurphyGuy Thank you for sharing renvu. They have some great prices as well!

If I go with SMA or Solis or Sol-Ark, I would likely have to use a combiner. Am I losing much by using a combiner? I would think that each string being on it's own MPPT would be the most ideal, but would it REALLY make much of a difference?

 

[live4soccer7]

All without shipping:

SMA Sunny Boy 7.7kw x 5 = $6845. About .18/w (38.5kw total)
Fronius 15.0kw x 3 = $11,031 about .25/w (45kw total)
Solis grid tie only x 4 = $4,056 about .12/w (40kw)
Solis Hybrid x 4 = $6052 about .15/w (40kw)
Sol-ark x 3-4 = WAY TOO EXPENSIVE. lol. It is around .66/w

Really, the SMA does stand out here, but the max voltage is quite a bit less which means I would likely have to do a combiner as opposed to likely not having to on the Fronius. BUT with this Sunny boy, I would be able to have the option for SPS plugin and you guys are saying I can add batteries down the road with the below sunny boy?

SMA Sunny Boy 7.7kW String Inverter w/ SPS 3 MPPT

DetailsSMA Sunny Boy 7.7kW String Inverter w/ SPS 3 MPPTNote: Mounting bracket is now integrated into the rear of the case (it used to be a separate metal bracket). SMA Sunny Boy SB-7.7-US 1-Ph Grid Tied Inverter, Sunspec Certified7700W, 208/240VAC, 60Hz, integrated DC Disconnect 2,000W SPS...

www.renvu.com

Maybe someone can help me with this. On the fronius, it states 15kw inverter, but max pv is 18kw. The SMA 7.7kw says max pv is 12.3kw. I guess I'm just looking to understand that and go about finding meaning in the two different numbers/ratings.

 

[MurphyGuy]

All without shipping:

SMA Sunny Boy 7.7kw x 5 = $6845. About .18/w (38.5kw total)
Fronius 15.0kw x 3 = $11,031 about .25/w (45kw total)
Solis grid tie only x 4 = $4,056 about .12/w (40kw)
Solis Hybrid x 4 = $6052 about .15/w (40kw)
Sol-ark x 3-4 = WAY TOO EXPENSIVE. lol. It is around .66/w

Really, the SMA does stand out here, but the max voltage is quite a bit less which means I would likely have to do a combiner as opposed to likely not having to on the Fronius. BUT with this Sunny boy, I would be able to have the option for SPS plugin and you guys are saying I can add batteries down the road with the below sunny boy?

SMA Sunny Boy 7.7kW String Inverter w/ SPS 3 MPPT

DetailsSMA Sunny Boy 7.7kW String Inverter w/ SPS 3 MPPTNote: Mounting bracket is now integrated into the rear of the case (it used to be a separate metal bracket). SMA Sunny Boy SB-7.7-US 1-Ph Grid Tied Inverter, Sunspec Certified7700W, 208/240VAC, 60Hz, integrated DC Disconnect 2,000W SPS...

www.renvu.com

Maybe someone can help me with this. On the fronius, it states 15kw inverter, but max pv is 18kw. The SMA 7.7kw says max pv is 12.3kw. I guess I'm just looking to understand that and go about finding meaning in the two different numbers/ratings.

The SMA 7.7 has 3 MPPT inputs so you would hook up to with with 3 individual strings of panels stacked to about 450 volts or so. No combiner box needed, just 3 positives and 3 negatives going into the 6 connectors. For me, this means between 8 and 12 panels on a string depending on panel voltage.

While I happen to be an SMA fan because of my (limited) positive experience with them in both grid tied and off grid, I don't think you'll go wrong with either the SMA or the Fronius.. but I wouldn't even consider Solis or Sol-Ark.. stay the hell away from anything related to China.

Let me tell you a story.. My first 28 panels (back in 2017) were SolarWorld panels.. a German outfit like SMA.. Life has taught me that German engineers are among the best in the world, so I went with the SolarWorld panels and SMA inverters. A few months later, I read that SolarWorld had a recall on some of their panels.. (not my batch though). What went wrong with them? SolarWorld ran out of MC4 connectors and their regular supplier had a backlog so they ordered from a Chinese supplier.... those MC4 connectors ended up being made with a plastic that had impurities and those impurities were causing the connectors to form micro cracks allowing moisture in which then corroded the connection, increased resistance, and melted the wire and connector. They ordered one freaking small part from China and even it wasn't made correctly..

You are right that the max voltage of the SMA is less than the Fronius, but the SMA also has more MPPT inputs so it all works out. I also know for a fact that the SunnyBoy can do Frequency Shift Power Control (AC Coupling) which allows you to turn your grid-tied system into an off-grid system by flipping a couple of switches.. You'll have to check to see if Fronius can do AC Coupling.. I'm guessing they can but you should check.

The max PV rating is mostly for us northerners with low sun angles in the winter.. before I installed my 2nd inverter, my first inverter (Sunny Boy 6.0kW) was hooked to 7.6kW of solar panels. During cool spring days, this means it would "clip" at 6kW even though the panels were making closer to 7kW of power.. but its only for a couple hours a day, and only for a few weeks a year when perfect environmental conditions line up to allow a 300 watt panel to actually make 300 watts.. or close to it. Most of the time, solar panels only make about 50% to 70% of their rated power if even that much.
But come spring when the angle of the sun lines up exactly with your solar array, a clear blue sky, and a cold day, and those panels will make near 100% of their rated output.. but it only lasts for an hour or so.. I've actually seen mine make 105%, but that only lasts for minutes, and its rare because it takes a special kind of cloud to float over nearby to reflect extra light.

 

[live4soccer7]

The SMA 7.7 has 3 MPPT inputs so you would hook up to with with 3 individual strings of panels stacked to about 450 volts or so. No combiner box needed, just 3 positives and 3 negatives going into the 6 connectors. For me, this means between 8 and 12 panels on a string depending on panel voltage.

While I happen to be an SMA fan because of my (limited) positive experience with them in both grid tied and off grid, I don't think you'll go wrong with either the SMA or the Fronius.. but I wouldn't even consider Solis or Sol-Ark.. stay the hell away from anything related to China.

Let me tell you a story.. My first 28 panels (back in 2017) were SolarWorld panels.. a German outfit like SMA.. Life has taught me that German engineers are among the best in the world, so I went with the SolarWorld panels and SMA inverters. A few months later, I read that SolarWorld had a recall on some of their panels.. (not my batch though). What went wrong with them? SolarWorld ran out of MC4 connectors and their regular supplier had a backlog so they ordered from a Chinese supplier.... those MC4 connectors ended up being made with a plastic that had impurities and those impurities were causing the connectors to form micro cracks allowing moisture in which then corroded the connection, increased resistance, and melted the wire and connector. They ordered one freaking small part from China and even it wasn't made correctly..

You are right that the max voltage of the SMA is less than the Fronius, but the SMA also has more MPPT inputs so it all works out. I also know for a fact that the SunnyBoy can do Frequency Shift Power Control (AC Coupling) which allows you to turn your grid-tied system into an off-grid system by flipping a couple of switches.. You'll have to check to see if Fronius can do AC Coupling.. I'm guessing they can but you should check.

The max PV rating is mostly for us northerners with low sun angles in the winter.. before I installed my 2nd inverter, my first inverter (Sunny Boy 6.0kW) was hooked to 7.6kW of solar panels. During cool spring days, this means it would "clip" at 6kW even though the panels were making closer to 7kW of power.. but its only for a couple hours a day, and only for a few weeks a year when perfect environmental conditions line up to allow a 300 watt panel to actually make 300 watts.. or close to it. Most of the time, solar panels only make about 50% to 70% of their rated power if even that much.
But come spring when the angle of the sun lines up exactly with your solar array, a clear blue sky, and a cold day, and those panels will make near 100% of their rated output.. but it only lasts for an hour or so.. I've actually seen mine make 105%, but that only lasts for minutes, and its rare because it takes a special kind of cloud to float over nearby to reflect extra light.

Great info, again.

Where my problem here lies is that each pv string that I run without combining has to make a 200' run back to the inverters that are near the net-meter. That wire is not cheap either and that adds up to a lot of wire to do 5 x 7.7kw sunny boys that way. That would be 15 pair of wires. 30 x 200' = 6000' of PV wire.

 

[live4soccer7]

Not that I really know exactly how it works, but it seems it is possible with the fronius system:

AC-coupled PV with Fronius PV Inverters [Victron Energy]

www.victronenergy.com

I'm not sure if that is more proprietary with the victor energy system or if it would work with any system that supports Frequency Shift Power Control (AC Coupling).

What are you guys using for battery backup or what would you use if you added it?

I think the fronius units are actively cooled with a fan, which may be better than passive on the SMA. I am confirming price on the wire as well. The pricing of the units may be pretty similar after I account for the additional wire I would need for the SMA units.

 

[MurphyGuy]

Not that I really know exactly how it works, but it seems it is possible with the fronius system:

AC-coupled PV with Fronius PV Inverters [Victron Energy]

www.victronenergy.com

I'm not sure if that is more proprietary with the victor energy system or if it would work with any system that supports Frequency Shift Power Control (AC Coupling).

What are you guys using for battery backup or what would you use if you added it?

I think the fronius units are actively cooled with a fan, which may be better than passive on the SMA. I am confirming price on the wire as well. The pricing of the units may be pretty similar after I account for the additional wire I would need for the SMA units.

If an inverter is capable of FSPC (Freq Shift Pwr Control = AC Coupling), then any bidirectional battery inverter capable of raising and lowering its own grid frequency should work with the grid tied inverter.
The grid inverter doesn't care who's doing it, it just responds to the frequency shift by throttling its power output.

I use two SMA Sunny Island battery inverters for my battery backup... Unlike the Fronius vs SunnyBoy competition, there is no close competitor to a Sunny Island.. they are the best there is, hands down.. its not even a conversation.

They are expensive.. in a distance 2nd place comes everything else. Victron, Magnum, Outback, etc.. all about equal to each other more or less..

As for the battery system, that kind of depends on your budget and skills.. If you don't have the budget, you need the skills to build your own.. and if you don't have the skills, you'll need the budget.

I use a 25kWh lithium ion battery, the cells came from a Chevy BOLT EV car. You can buy manufactured lithium backup batteries, but I suggest again that you stay away from anything made in China.
Or you can go with the old reliable workhorse and use a Flooded Lead Acid battery.. in which case, I strongly suggest the Trojan SIND line or a Rolls.. the rest are hobby level junk that will last a few years and then need replacement.

Lead acid doesn't like to be stuck on shelf doing nothing, so not the best choice for an emergency backup system.. If you go with lead acid, you'll need to exercise them at least once or twice a month.

 

[live4soccer7]

If an inverter is capable of FSPC (Freq Shift Pwr Control = AC Coupling), then any bidirectional battery inverter capable of raising and lowering its own grid frequency should work with the grid tied inverter.
The grid inverter doesn't care who's doing it, it just responds to the frequency shift by throttling its power output.

I use two SMA Sunny Island battery inverters for my battery backup... Unlike the Fronius vs SunnyBoy competition, there is no close competitor to a Sunny Island.. they are the best there is, hands down.. its not even a conversation.

They are expensive.. in a distance 2nd place comes everything else. Victron, Magnum, Outback, etc.. all about equal to each other more or less..

As for the battery system, that kind of depends on your budget and skills.. If you don't have the budget, you need the skills to build your own.. and if you don't have the skills, you'll need the budget.

I use a 25kWh lithium ion battery, the cells came from a Chevy BOLT EV car. You can buy manufactured lithium backup batteries, but I suggest again that you stay away from anything made in China.
Or you can go with the old reliable workhorse and use a Flooded Lead Acid battery.. in which case, I strongly suggest the Trojan SIND line or a Rolls.. the rest are hobby level junk that will last a few years and then need replacement.

Lead acid doesn't like to be stuck on shelf doing nothing, so not the best choice for an emergency backup system.. If you go with lead acid, you'll need to exercise them at least once or twice a month.

Yeah, those aren't cheap. haha. I've got to sit down and do some numbers and settle on what I'll do for the sma/fronius debacle here. Would I be unwise to do let's say 2 fronius and 1 SMA or should I stick with one particular brand?

 

[wattmatters]

Maybe someone can help me with this. On the fronius, it states 15kw inverter, but max pv is 18kw. The SMA 7.7kw says max pv is 12.3kw. I guess I'm just looking to understand that and go about finding meaning in the two different numbers/ratings.

The inverter rating is their maximum AC output, not the rated DC input they can accept.

Most grid tied inverters at this scale can accept a maximal PV input of ~1.5 times (give or take) the inverter's AC output rating. That enables them to generate a greater output in lower light conditions.

It's actually encouraged to "oversize" an array. A DC:AC ratio around 1.33 makes for a good compromise between getting good production in lower light conditions while not losing all that much production potential when solar production conditions are excellent. It makes for efficient use of the inverter's capacity.

Lead acid doesn't like to be stuck on shelf doing nothing, so not the best choice for an emergency backup system..

If they are kept on float, or have charged maintenance each day they are perfect for an emergency backup system, which is why data and telecom centres the world over use lead acid batteries for this purpose, and still do. What they don't like is high temperatures and frequent deeper discharges.

But for regular cycling in a static scenario such as a home discharging a battery each night, LiFePO4 is the superior choice (but need temperature control, especially on the cold end of the spectrum).

If an inverter is capable of FSPC (Freq Shift Pwr Control = AC Coupling), then any bidirectional battery inverter capable of raising and lowering its own grid frequency should work with the grid tied inverter.
The grid inverter doesn't care who's doing it, it just responds to the frequency shift by throttling its power output.

One of the issues to sort through with back up is how you wish such a system to operate. Is it going to be an automated cutover, what do you want to actually operate while on backup and do you want a backup system to also have the ability to be charged by PV when operating off-grid thereby extended the duration backup is available for? The first two are not overly complicated to sort out.

In the latter case it will take some planning and care in set up as you can't have too large of an array feeding the battery system. Last thing you want is a full battery, midday solar PV pumping maximal output to the grid and suddenly the grid goes down and your system has to rapidly dump that DC somewhere in the interim before the inverter's frequency control can ramp down production. Often you will couple only a portion of a large PV system to form a microgrid with the battery's inverter, while allowing the rest of the PV system to shut down during grid outages.

If you don't care about the battery being charged by solar PV when grid is down, then an AC coupled battery will just present itself as a (variable) load on the system and that's pretty simple. No need to worry about frequency control.

Given the tariff regime in play (i.e. feed in credit = grid import tariff and the tariffs are flat rate not time of use) I see little point in having a battery system for anything other than backup.

And if outages are uncommon then honestly it'll just be cheaper to have a regular generator on hand you can plug in to supply the designated critical circuits. One which can accept both petrol or propane as fuel. Propane is good as a fuel as it will store for a long time without spoiling.

 

[live4soccer7]

The inverter rating is their maximum AC output, not the rated DC input they can accept.

Most grid tied inverters at this scale can accept a maximal PV input of ~1.5 times (give or take) the inverter's AC output rating. That enables them to generate a greater output in lower light conditions.

It's actually encouraged to "oversize" an array. A DC:AC ratio around 1.33 makes for a good compromise between getting good production in lower light conditions while not losing all that much production potential when solar production conditions are excellent. It makes for efficient use of the inverter's capacity.


If they are kept on float, or have charged maintenance each day they are perfect for an emergency backup system, which is why data and telecom centres the world over use lead acid batteries for this purpose, and still do. What they don't like is high temperatures and frequent deeper discharges.

But for regular cycling in a static scenario such as a home discharging a battery each night, LiFePO4 is the superior choice (but need temperature control, especially on the cold end of the spectrum).


One of the issues to sort through with back up is how you wish such a system to operate. Is it going to be an automated cutover, what do you want to actually operate while on backup and do you want a backup system to also have the ability to be charged by PV when operating off-grid thereby extended the duration backup is available for? The first two are not overly complicated to sort out.

In the latter case it will take some planning and care in set up as you can't have too large of an array feeding the battery system. Last thing you want is a full battery, midday solar PV pumping maximal output to the grid and suddenly the grid goes down and your system has to rapidly dump that DC somewhere in the interim before the inverter's frequency control can ramp down production. Often you will couple only a portion of a large PV system to form a microgrid with the battery's inverter, while allowing the rest of the PV system to shut down during grid outages.

If you don't care about the battery being charged by solar PV when grid is down, then an AC coupled battery will just present itself as a (variable) load on the system and that's pretty simple. No need to worry about frequency control.

Given the tariff regime in play (i.e. feed in credit = grid import tariff and the tariffs are flat rate not time of use) I see little point in having a battery system for anything other than backup.

And if outages are uncommon then honestly it'll just be cheaper to have a regular generator on hand you can plug in to supply the designated critical circuits. One which can accept both petrol or propane as fuel. Propane is good as a fuel as it will store for a long time without spoiling.

Thanks! I don't plan on doing batteries, but if the utility company changes the way power is billed (ie higher rates at night) or changes import/export etc... then it may be a good option to have. Alternately, if rolling outages become a problem in the area then it would be another good reason to have a system that could adapt to some sort of battery backup.

Agreed on the generator. It is cheaper by far to just have a genny running for a short period of time.

Edit: I'm going to play around with some numbers more this weekend. Hopefully, I can find a good amount of time for this over the weekend. I would like to get my application submitted to the utility company this week to get a hard confirmation on allowing the system size. I was told over the phone it wouldn't be an issue, but that's not quite "official". From there I will submit for electrical permit and then the building permit with the county for the system. Once all that is approved then I will go forward with beginning to spend all my money. haha

 

[Sanwizard]

I would stick with SMA.
I would avoid Sol-Ark = Chinese

Fronius does look like a better fit wattage wise as some of their inverters can push a lot of power.. Renvu has SMA SunnyBoy 7.7's on sale for 18 cents a watt while the price I was seeing for the Fronius is up around 28 cents. That's a big increase. Might be beneficial to have multiple inverters that would provide redundancy..
Not sure about Fronius, but the SMA's have an off-grid feature that provides 120 volts at 2000 watts to a special circuit.

I was surprised to find that the big Fronius inverter has a narrow MPP voltage range of 320 to 480. That's pretty tight and could limit your design considerations. SMA has a huge MPP voltage range from 100 to 550 volts allowing far more flexibility.

The Fronius has only two MPPT inputs where the SMA SunnyBoy has 3, and they can operate at a higher voltage.

You want to kind of make sure you match your panels to the MPPT input specs..

Where are you finding 450 watt Hyundai panels? I can't find a listing for them anywhere. That said, the Fronius inverter has only 2 MPPT inputs for up to 30 amps each.. with most 400+ watt panels pushing 10 amps, that means you'll need to parallel panels, which will also require you to install combiner boxes, breakers, etc.. all adding extra complexity and cost to the system.

All my equipment is SMA, both the grid tie and the off grid.. It runs flawlessly and reliably... I can't speak about Fronius other than the tech specs I'm reading, but I'm really glad I went with SMA..
View attachment 65016

What batteries do you use with your SMA off grid? I find that a limiting factor, as the SMA's need seperate everything, and specific batteries. $800 just for web connectivity? Midnight solar MPPT? Shunts? CT's? Why so complex?

 

[MurphyGuy]

What batteries do you use with your SMA off grid? I find that a limiting factor, as the SMA's need seperate everything, and specific batteries. $800 just for web connectivity? Midnight solar MPPT? Shunts? CT's? Why so complex?

I built my own battery system from Chevy BOLT EV cells.

My entire system consists of the panels and grid tied inverters, Sunny Islands, the battery cells, and a BMS.. that's it. Everything is inside a box on wheels... which now doubles as one more flat surface for everyone to leave things on.

I think the complex systems you see everywhere are the result of a lack of planning. Some of these systems I see with wires hanging everywhere and things just screwed to a plywood board make me cringe.

 

[RV10flyer]

Starting my 20.6 kw / 112 kWh system in a few weeks too. Waiting for work to slow and weather to cool here at 38 deg Lat.