Am I Crazy? Seems like a Lot more Off Grid System being Built by Grid Users Lately

[SpongeboB Sinewave]

Argeed. I would have thought hi frequency too, but @BMcL notes his as low. So I do not know.

Yes. But even what people call low frequency inverters are really high frequency PWM and just use a low frequency transformer.

We all know this of course. Just terminology.

I haven't seen a low-frequency modified square wave low frequency inverter in quite a while now. Not for sale anyway.

boB

 

[fafrd]

Not really. My peak tariff is ~21.5c (US cents equivalent) and off-peak is 11c/kWh. But it does vary depending on where you are in the country.

And we don't get 1:1 for power fed back to the grid, our feed in tariffs are falling. At the moment I get ~5c/kWh for power fed back to the grid.

The big difference here is that even though overall incentives for installing small scale solar PV are similar, grid-tied solar PV is way, way cheaper to get installed here than in the USA.

Typically you'll pay ~US $500-700/kW for grid tied rooftop solar PV installed by solar PV professionals. More for say an Enphase system (up to US$1000/kW). This means the amortised cost per kWh over 20 years is ~3-4c/kWh. Call it 5c/kWh if you allow for slightly shorter life from your inverter.

In some places the cost to install can be as low as US$300/kW.

We have a very efficient solar PV installation industry.

You originally said payback in 3-5 years and if export credit is only ~half of consumption cost, I’m still having some trouble with the math.

You spend $300/kW which here in California, would translate to about 1250kWh of production per year, or $62.50 annually at credit of $0.05/kWh.

So I can see how that best-case gets you to a break-even of less than 5 years, but getting down to 3 years means that down in Australia, you must be able to get closer to $100/year in generation credit rather than the $62.50 you’d get here in often-overcast Northern California.

So yeah, if 2kWh/W is a realistic annual production level down there, no wonder solar is so popular… .

 

[Quattrohead]

Transformers are dumb, they do 1 thing BUT they do it so well. Transformer failures are super rare compared to other electronic components.
The electrical/physical bulk of a transformer protect the PWM driver from the hard work and hence give you a reliable and sturdy power supply.

 

[wattmatters]

You originally said payback in 3-5 years and if export credit is only ~half of consumption cost, I’m still having some trouble with the math.

Here's my average daily electricity cost (in AUD) before and after installing our 11kW grid-tied solar PV system (10kW Fronius Symo 3-phase inverter + consumption meter), which at the time cost us A$12.8k (~US$9.0k). Systems are a bit cheaper nowadays.



IOW a reduction of about $9/day ~= $3200/year

System cost $12.8k / $3.2k = 4 years.

Now not all of that is all due to solar PV, there is some energy efficiency as well but about 80% of it is due to the solar PV. So let's call it 5 years to payback. Mind you, much of the efficiency comes from the data analytics the solar PV system enabled. It's a positive feedback system.

Homes with solar PV tend to become more energy literate, they seek out ways to make the most of their own production.

We are an all electric home.

4-5 years is a pretty typical payback for grid tied solar PV in Australia. If it were a lot longer, do you think one-quarter of all households would have one? Australia has less than 8% of the population (25.7M) of the USA (329.5M) but has 50% more rooftop solar PV systems (3 million v 2 million). Current average size of systems being installed today is 8kW.

My system will generate energy over its lifetime at a cost of ~A 4.7c/kWh (~US 3.3c/kWh). That's half to one-third of typical off-peak rates and one-quarter to one-eighth of typical peak rates (depending on where you are). Feed in tariffs were better, which helped, but they are falling and will settle to nearer the daytime wholesale price of electricity, which will still be no less than what my system production cost is.

Solar is most financially beneficial if you shift as much discretionary load as possible to the daytime. Stuff like diverting energy to hot water storage is pretty common here. Other examples are aircon and in future EV charging.

 

[BMcL]

What is the idle power consumption of a single LVX6548? Will that number double when you stack 2 units?

Yes, there is another thread discussing this right now. The "Tier-1" units (Outback and Sol-ark among many) have the lowest consumption.
Personally, the money should be spent on more batteries than paying big premiums for the best inverter.
Batteries are very expensive and you need lots of them. I have 26kw and need to double that at a minimum.
JMHO. I hope I don't have to buy two Outback 8048's after going with the MPP Solar. That would hurt

 

[BMcL]

Agreed. I would have thought hi frequency too, but @BMcL notes his as low. So I do not know.

I think the market is coming out with better options as the cost of installing a system has come down and demand has gone way up.
Here is the description that Ian has on his website about the MPP Solar LVX6048WP :

LVX6048WP should be here early 2022 about the $1.8k range, add yourself to the waitlist​

$1,850.00

It is the waterproof version of the upgraded LVX6048 (more solar input capacity too!), Grid feedback, battery optional, dual mppts, Low Frequency, split phase ……. stackable you name it, wifi..
-------------
That doesn't prove it's low frequency, but it's weight is listed at 100 lbs. Heavier by 20 lbs than previous models, but still not in the category of an Outback 8KW (200 lbs)

 

[740GLE]

That and the sun shines a bit brighter in Australia than the Northern US

 

[wattmatters]

That and the sun shines a bit brighter in Australia than the Northern US

Northern US, definitely, although annual solar production per kW of PV is actually better across large swathes of the US than Australia.

 

[Ampster]

I use the metric of dollars per Watt and I thought I was doing well at just about $2 per Watt then I checked the math and that is $2,000 USD per kilowatt. @wattmatters , is that USD or Aus$?

 

[wattmatters]

I use the metric of dollars per Watt and I thought I was doing well at just about $2 per Watt then I checked the math and that is $2,000 USD per kilowatt. @wattmatters , is that USD or Aus$?

Can you quote what you are asking about?

 

[MurphyGuy]

We installed our 11kw Grid Tied solar in 2017.. that year, we had 5 power outages with 2 of them almost a week long.

In 2018, we had 9 power outages, most were just a day long, one was three days.

In 2019, we had 6 power outages, most were just a day, one was almost a week.

2020 wasn't so bad.

Living out in the rural countryside means we are last to be fixed when a big storm rolls through.

Our grid tied system doesn't work when the grid goes down, and while we do have a tri-fuel generator capable of powering 90% of the house, its loud an annoying and I hate listening to it. So I installed an AC Coupled battery backup system.. Its manually activated, but when the grid goes down, I flip a couple switches and we're up and running with the 11kW solar system keeping 25kWh of battery bank charged. This results in life-as-normal as we have enough power that we can ignore the fact that we're off grid.

We are preppers, we stock food and other supplies, we store long term seeds, have multiple ways of generating energy, and could easily survive in comfort for about 3 years before we had to get to work growing our own food. Having an off-grid backup system was just part of all that.

I built the off-grid part for about $5500.. Some people blow that much money every year on tobacco and alcohol..

Here's a photo of the off grid portion. The steel box has the lithium ion battery bank inside.

 

[Ampster]

Can you quote what you are asking about?

I can't find it now but will keep looking. I thought I saw you say systems in Australia were costing $700 per kW?

 

[pollenface]

I built my first system to get lighting in a garden shed as I was sick of running extension leads to it. I enjoyed the process of putting everything together and the satisfaction I got from seeing everything working and later expanded to other areas of the home such as my workshop and garage. My wife appreciates being able to open the garage door, or charge her phone or keep watching Netflix during a blackout.

I do have a grid-tied solar system as well.

 

[wattmatters]

I thought I saw you say systems in Australia were costing $700 per kW?

US$700/kW is a pretty standard price for a grid tied solar PV system full installed, if not a little high. That would be any one of a range of quality inverters, panels and hardware. Some places the install cost is closer to US$500/kW, while a tricky roof with say an Enphase system would be more like US$1k/kW.

e.g. in most major cities, the cost of a 10kW system is going to be ~A$8,400 ~= US$6,000.

Solar installation industry here is very competitive and quite efficient. We also have some federal solar rebates, but the scale of the incentive is about the same value as the federal tax rebate in the US. In some cases the US rebate is more generous.

Here's the trend for grid tied solar PV installation costs here. This is in AUD (~= US$0.71):

Solar Panel Costs: Solar Choice Price Index | April 2024

The Solar Choice Price Index measures the cost of solar power systems on a dollar per watt ($/W) basis. This pricing metric helps consumers and industry

www.solarchoice.net.au

 

[MrM1]

We installed our 11kw Grid Tied solar in 2017.. that year, we had 5 power outages with 2 of them almost a week long.

In 2018, we had 9 power outages, most were just a day long, one was three days.

In 2019, we had 6 power outages, most were just a day, one was almost a week.

2020 wasn't so bad.

Living out in the rural countryside means we are last to be fixed when a big storm rolls through.

Our grid tied system doesn't work when the grid goes down, and while we do have a tri-fuel generator capable of powering 90% of the house, its loud an annoying and I hate listening to it. So I installed an AC Coupled battery backup system.. Its manually activated, but when the grid goes down, I flip a couple switches and we're up and running with the 11kW solar system keeping 25kWh of battery bank charged. This results in life-as-normal as we have enough power that we can ignore the fact that we're off grid.

We are preppers, we stock food and other supplies, we store long term seeds, have multiple ways of generating energy, and could easily survive in comfort for about 3 years before we had to get to work growing our own food. Having an off-grid backup system was just part of all that.

I built the off-grid part for about $5500.. Some people blow that much money every year on tobacco and alcohol..

Here's a photo of the off grid portion. The steel box has the lithium ion battery bank inside.

Nice what size inverter for off grid?

 

[MrM1]

I built my first system to get lighting in a garden shed as I was sick of running extension leads to it. I enjoyed the process of putting everything together and the satisfaction I got from seeing everything working and later expanded to other areas of the home such as my workshop and garage. My wife appreciates being able to open the garage door, or charge her phone or keep watching Netflix during a blackout.

I do have a grid-tied solar system as well.

Yes it is very rewarding

 

[MurphyGuy]

Nice what size inverter for off grid?

The yellow boxes are SMA Sunny Islands. We use two of them to make a 120/240 split phase system for a total of 12kW. They are true low frequency inverters and can run my air conditioner without even breaking a sweat.

They're the best inverters on the market and no one even argues that fact.. but they're kind of pricey at around $5k each. I bought them from the DC Solar scam that flooded ebay with them. Paid $1100 each shipped.

 

[MrM1]

The yellow boxes are SMA Sunny Islands. We use two of them to make a 120/240 split phase system for a total of 12kW. They are true low frequency inverters and can run my air conditioner without even breaking a sweat.

They're the best inverters on the market and no one even argues that fact.. but they're kind of pricey at around $5k each. I bought them from the DC Solar scam that flooded ebay with them. Paid $1100 each shipped.

Not familiar with the "DC Solar Scam", but at $5k, not sure why someone would choose the Sunny Island over the Schneider XW that is at least $1.5k less. But if you got them for $1100 ... yeah i'd do that !!

 

[Ampster]

Not familiar with the "DC Solar Scam"

https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.justice.gov/usao-edca/pr/dc-solar-owner-sentenced-30-years-prison-billion-dollar-ponzi-scheme&ved=2ahUKEwizwcaXwM31AhXTFzQIHbq1AhIQFnoECAUQAQ&usg=AOvVaw2bQFYIS5tPo8VkiJlFkPHw

 

[MrM1]

https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.justice.gov/usao-edca/pr/dc-solar-owner-sentenced-30-years-prison-billion-dollar-ponzi-scheme&ved=2ahUKEwizwcaXwM31AhXTFzQIHbq1AhIQFnoECAUQAQ&usg=AOvVaw2bQFYIS5tPo8VkiJlFkPHw

So the Scammer went to jail, and surplus inverters got liquidated on ebay?