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Newbie Help...Hybrid Solar-Wind System

Regina

New Member
Joined
Jul 1, 2021
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5
Hi all! I'm new here and we're getting ready to start the process to get solar for our home, as both back-up for power failure and also powering some of what we use on the solar to reduce electric bills. We do not want a grid-tie as it provides little to no benefit for us, rather this will be a system we build as "off grid" that can also charge via AC power if needed.

Looking at our current usage, we want a system that we can expand over time, but have enough in place initially to cover our basic needs in the event of a power failure. Currently our usage is high (don't judge, it is what it is) at an average 74.5Kwh a day, or 2,236Kwh a month. Our peak use is 3,057Kwh in a month, our low use is 1,609Kwh in a month. I got these numbers by reviewing our 2020 usage, month by month.

I am looking to start with 2 BigBattery TREX (12.8Kwh) that will give us 25.6Kwh of power in batteries; they're 48V batteries. Over the next few years we'd likely look to expand that up to 102.4Kwh stored.

I'm trying to decide on whether I set up 2 MPP Solar LV2424 or 2 LVLV6048 controller/inverter boxes. I'm also trying to understand if I'd need to continue adding boxes in the future with additional batteries added over time.

I'm also trying to figure out our best option for solar panels...for our future needs, it's an insane amount of panels needed!

More importantly, I'm trying to figure out if the controller/inverter boxes can also have wind turbine energy as an input - where we live (central midwest) we have great sun from April to October, then consistent breezy wind from November to March, along with wind all year even in the summer months, especially when we're having our spring storms....so I'd like to look at options to add a wind turbine (or multiple turbines), but information is scant on how I can add that to a solar system to get power from both sun and wind. Does anyone have any good information on how to do this, or where I can look to better understand how to create a hybrid system.

What I've been looking at above is just the basics, I'm open to using different products if they're going to better meet our needs for our initial system and later expansion.

Thanks for your help!
 
Welcome to the forum.

Given the loads expected with such high usage, you likely are powering devices that are beyond the reach of the cheap chinese inverters (MPP Solar/Growatt). Something like 48000W may be required to start a 5 ton A/C unit, and most of the high frequency units have terrible surge capabilities. Additionally, they are particularly greedy with their idle power consumption, i.e., they burn a lot of juice just by being turned on and powering no loads. Those two 6048 units will likely eat at least 3.6kWh/day just by being on.

Wind should be thought of separately, i.e., as you would hook up multiple MPPT as you expand your solar, you can add wind with its own charge controller; HOWEVER, it's very important to thoroughly research wind to establish realistic expectations and determine if it's really worth pursuing.

 
Welcome to the forum.

Given the loads expected with such high usage, you likely are powering devices that are beyond the reach of the cheap chinese inverters (MPP Solar/Growatt). Something like 48000W may be required to start a 5 ton A/C unit, and most of the high frequency units have terrible surge capabilities. Additionally, they are particularly greedy with their idle power consumption, i.e., they burn a lot of juice just by being turned on and powering no loads. Those two 6048 units will likely eat at least 3.6kWh/day just by being on.

Wind should be thought of separately, i.e., as you would hook up multiple MPPT as you expand your solar, you can add wind with its own charge controller; HOWEVER, it's very important to thoroughly research wind to establish realistic expectations and determine if it's really worth pursuing.

Thank you for the link, I have some reading to do! BTW, the links in your signature are helpful too!

With regard to the AC - yup it's our biggest energy hog and at this point, it's an older unit, installed about 15 years ago (10-ton unit), if we were to have a power failure, it'd be off as I don't need to waste our backup energy on AC when I'd rather keep the refrigerator on! Given the age of the AC we've been exploring options for the future when we replace it since it's not energy efficient, though it does cool the house insanely well, but that's a whole other topic....but I think some mini-splits are in our future!

If I take the AC out of the picture, I think everything else can be managed on the LV2424 or the LV6048, though I might be wrong - I'm still trying to understand how it all works! Our only other energy hogs are our electric clothes dryer and electric wall oven (both I can live without if needed since I can hang clothes to dry and our counter rangetop is gas, so I can still cook). One of the biggest reasons we haven't gone full solar is the cost to do whole house for us - where we live electricity is cheap, so we haven't paid much attention to our usage since our bills aren't insanely high - but I don't think cheap electricity is going to continue in the future for one, and we'd also like some back-up in the event of a power failure, ya know?
 
10 ton unit? Wow.

You need to be mindful of anything with a motor. Motors have very high surge currents for several seconds that are often beyond the capability of high frequency inverters (LV2424, LV6048, etc) unless the surge is below or just over their continuous rating.

Generally speaking, when one is seeking reliable power independence, the best place to look is usually not at the bottom of the cost and efficiency barrel. A few extra thousand gets you much higher reliability and capabilities with greater efficiencies. Quite a number of issues with these units behaving oddly and inconsistently.

If I want to power a shed or a project that I want cheap solar for, I'll get a growatt/MPP Solar. If I want grid-like reliability (less than a dozen power outages in the last 23 years here in Mesa, AZ), I want Victron, Outback, Midnite, Magnum, Xantrax, Schneider, etc. Yes, you will spend more. Yes, it's worth it.

I paid out the nose for Victron hardware for our off-grid property. I'd do it again.

Completing the energy audit in link #1 will help you determine that.
 
10 ton unit? Wow.

You need to be mindful of anything with a motor. Motors have very high surge currents for several seconds that are often beyond the capability of high frequency inverters (LV2424, LV6048, etc) unless the surge is below or just over their continuous rating.

Generally speaking, when one is seeking reliable power independence, the best place to look is usually not at the bottom of the cost and efficiency barrel. A few extra thousand gets you much higher reliability and capabilities with greater efficiencies. Quite a number of issues with these units behaving oddly and inconsistently.

If I want to power a shed or a project that I want cheap solar for, I'll get a growatt/MPP Solar. If I want grid-like reliability (less than a dozen power outages in the last 23 years here in Mesa, AZ), I want Victron, Outback, Midnite, Magnum, Xantrax, Schneider, etc. Yes, you will spend more. Yes, it's worth it.

I paid out the nose for Victron hardware for our off-grid property. I'd do it again.

Completing the energy audit in link #1 will help you determine that.
Thank you - this is the type of insight I really need, what is going to work best (not what's necessarily promoted heavily)!!!!
 
My system has been up for a couple of years now. I'm in Southern OR - mild weather - normal/seasonal sun. I can share some overall context.
I have
- Overall, yearly average, my house consumes 3046kw/hour. Peak at 114F is 6000kw/hour and 'normal' is 2300kw/hour.
- 12.8kw array of 45 panels @ 285w each
- 3 x Midnite Classic 150s
- 2 x AIMS 12,000w inverters.
- 80kwh battery bank - running 40% DOD (for extra long life) but 40kwh would work at 80% DOD.

Last year I produced 18,000kwh and after losses got 15,000kwh out of the inverters / consumed by the house.
Hi of 2000kwh/month in summer and low of 500kwh/month in winter.

For me, the big problem is the 3-4 months of winter - cloudy/rainy - and only 500kwh/month - e.g. not enough to live very comfortably in total power outage. So I bought another 40 (used/cheap) panels as my 'emergency backup generator' that I could temporary deploy to the back yard in winter if I had to. This would give me 85 panels @ 285w. They're stored under the house in the dark - should be good for many years and actually cheaper than trying to install 1000gal propane tank + generator. But I know - it sounds weird :)

That's the 'scale' of things for me. I agree that doing things incrementally is perfectly doable. I started with 15panels, then 24, then 45... adding additional charge controllers at each phase + expanding the battery bank. My advice - is plan the 'big picture' (at least rougly) to leave room for the ultimate goal. For example - don't just squeeze in 1 charge controller but leave room for 2 or 3 or 4 next to each other - it will ease wiring etc.
 
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Thank you - this is the type of insight I really need, what is going to work best (not what's necessarily promoted heavily)!!!!

If the appliance (e.g. A/C compressor) has a rating for "LRA" (locked rotor amps), use that to size the inverter. Either continuous wattage for that current, or surge rating if inverter has a surge rating good for several seconds. My Sunny Island for instance is rated 5750W continuous, 11kW for 3 seconds. If no LRA given, multiply the amperage rating by 5x; that's about what the surge current will be.

Some clamp meters can measure surge, but others may be too slow to show the full current. I recently got an "Ames" from Harbor Freight, don't know yet if its surge measurement is good but I plan to check it.


75 kWh/day is in the range I use. I have multiple Sunny Island and Sunny Boy. The battery inverters are normally excessively expensive, but some bargains are available in the U.S. It would still cost around $7k ~ $10k for 12 kW of battery inverter and 12 kW of PV inverter.

Batteries cost much more than PV. I prefer to have excess PV, waste what I don't use immediately. My system is grid-backup so I just conserve at night or during cloudy/smoky days. Off-grid a generator could let you get by with less battery. 100 kWh is going to be $10k to $25k or more so getting by with 20 kWh (what I have) or 40 kWh is a considerable cost reduction.
 
My system has been up for a couple of years now. I'm in Southern OR - mild weather - normal/seasonal sun. I can share some overall context.
I have
- Overall, yearly average, my house consumes 3046kw/hour. Peak at 114F is 6000kw/hour and 'normal' is 2300kw/hour.
- 12.8kw array of 45 panels @ 285w each
- 3 x Midnite Classic 150s
- 2 x AIMS 12,000w inverters.
- 80kwh battery bank - running 40% DOD (for extra long life) but 40kwh would work at 80% DOD.

Last year I produced 18,000kwh and after losses got 15,000kwh out of the inverters / consumed by the house.
Hi of 2000kwh/month in summer and low of 500kwh/month in winter.

For me, the big problem is the 3-4 months of winter - cloudy/rainy - and only 500kwh/month - e.g. not enough to live very comfortably in total power outage. So I bought another 40 (used/cheap) panels as my 'emergency backup generator' that I could temporary deploy to the back yard in winter if I had to. This would give me 85 panels @ 285w. They're stored under the house in the dark - should be good for many years and actually cheaper than trying to install 1000gal propane tank + generator. But I know - it sounds weird :)

That's the 'scale' of things for me. I agree that doing things incrementally is perfectly doable. I started with 15panels, then 24, then 45... adding additional charge controllers at each phase + expanding the battery bank. My advice - is plan the 'big picture' (at least rougly) to leave room for the ultimate goal. For example - don't just squeeze in 1 charge controller but leave room for 2 or 3 or 4 next to each other - it will ease wiring etc.
I've had a number of folks suggest back up panels instead of wind, so I may actually do that instead since the cost is about the same and good panels last way longer!

At this point we are trying to lay out what the final system will look like - I agree, having the end goal in mind is important since each expansion requires more room and additional wiring!
 
If the appliance (e.g. A/C compressor) has a rating for "LRA" (locked rotor amps), use that to size the inverter. Either continuous wattage for that current, or surge rating if inverter has a surge rating good for several seconds. My Sunny Island for instance is rated 5750W continuous, 11kW for 3 seconds. If no LRA given, multiply the amperage rating by 5x; that's about what the surge current will be.

Some clamp meters can measure surge, but others may be too slow to show the full current. I recently got an "Ames" from Harbor Freight, don't know yet if its surge measurement is good but I plan to check it.


75 kWh/day is in the range I use. I have multiple Sunny Island and Sunny Boy. The battery inverters are normally excessively expensive, but some bargains are available in the U.S. It would still cost around $7k ~ $10k for 12 kW of battery inverter and 12 kW of PV inverter.

Batteries cost much more than PV. I prefer to have excess PV, waste what I don't use immediately. My system is grid-backup so I just conserve at night or during cloudy/smoky days. Off-grid a generator could let you get by with less battery. 100 kWh is going to be $10k to $25k or more so getting by with 20 kWh (what I have) or 40 kWh is a considerable cost reduction.

I had a friend of ours, who is an electrician, look at what we're laying out and his suggestion was to ignore the air conditioner for now since it's too large a draw and look to be able to power that in the last phase since we'll likely have replaced what we have anyway to sometime more energy efficient in the coming couple of years. I'm actually shocked by how much electricty we use - I had no idea since I live in an area with cheap electricty - I don't even want to know what our bills would be if I lived in CA!
 
PV + GT inverter is so cheap now ($0.50/W) that it can produce power as cheap as $0.025/kWh (amortized over 10 years.)
Unlike before, running a power-hog A/C from PV is doable, maybe cheaper than replacing A/C. Biggest issue is surge current to start it.

If you get something like a window A/C sized so its rated current is no more than 20% of your inverter rating you can power it with what you have and make at least one room comfortable. An inverter drive unit (some mini-split) could be sized a larger percentage of your inverter rating and aren't terribly expensive.

Some places have utility rates $0.05/kWh. Here in California, $0.15 to $0.50/kWh. And they're banning natural gas in new construction.
People living in places like Sacramento sometimes have $700/month electric bills.
 
PV + GT inverter is so cheap now ($0.50/W) that it can produce power as cheap as $0.025/kWh (amortized over 10 years.)
Unlike before, running a power-hog A/C from PV is doable, maybe cheaper than replacing A/C. Biggest issue is surge current to start it.

Disagree based on my own investigation of going GT from scratch with 10kW of SanTan Panels and a GT inverter. Yes, cost of panels + GT inverter is about $0.50/Watt, BUT...

Once you consider consider mounting/installation hardware and code compliance to NEC2017, the cost doubles.

I am NOT talking about labor either. I am talking only about hardware costs for roof mounting. Ground mounting is a lot more simple and cost effective.
 
Disagree based on my own investigation of going GT from scratch with 10kW of SanTan Panels and a GT inverter. Yes, cost of panels + GT inverter is about $0.50/Watt, BUT...

Once you consider consider mounting/installation hardware and code compliance to NEC2017, the cost doubles.

I am NOT talking about labor either. I am talking only about hardware costs for roof mounting. Ground mounting is a lot more simple and cost effective.

correct, I forgot to say probably $1/W with mounts and electrical stuff, $0.05/kWh, assuming your labor is free.

Roof mount would have been simpler/cheaper but RSD boxes add to cost. Simple enough when inverter integrates RSD control, but I'm not seeing low cost.
Maybe DIY ground mounts can be cheap enough, if you find good surplus material.
 
correct, I forgot to say probably $1/W with mounts and electrical stuff, $0.05/kWh, assuming your labor is free.

Roof mount would have been simpler/cheaper but RSD boxes add to cost. Simple enough when inverter integrates RSD control, but I'm not seeing low cost.
Maybe DIY ground mounts can be cheap enough, if you find good surplus material.

I have a 12x30 aluminum awning over our south facing back porch... that is almost exactly the size I need to install 18 of the 36 285W panels I bought from Santan before doing the research (18 were relocated to HBR).

...install just enough to run most my 5 ton A/C connected on the "Off" side of the switch so the GT inverter never sees the grid unless it's on, and it never feeds back....

The power company might question why the load tapers off... :)
 
I keep detailed records. My 12.85kw PV array cost $1.16/w - this includes all mounting, permits, wire, conduit, mc4 connectors, lightning arrestors, combiner boxes, circuit breakers, junction boxes, electrician costs (mandated by the city), handyman to help install rails, US Fed govt tax credit, etc. This was 2 yrs ago.

I'm not arguing against $1/w and perhaps I overpaid a bit - just sharing what it actually cost me.
 
Ground mounting is a lot more simple and cost effective.
Exactly why I’d rather lay down a few extra panels than go wind at all, less noise, less bloody bird entrails landing in your martini glass on your deck, and more reliable… long term….

Truth be told, all it took was the lack of bird-slaw falling from the sky to convince me.…. LOL

Jen

 
Truth be told, all it took was the lack of bird-slaw falling from the sky to convince me.…. LOL

But the tortoises! Think about the tortoises!

And then there is the flying bald eagle roaster ...

Seriously, though, I don't think it is the number of birds killed that matters. It is the number of birds that live.
If wind energy kills some dare-devil birds, but significantly increases the number of surviving chicks due to less pollution, that is a win. That depends on what energy sources are offset by wind.
Endangered animal safety and human safety should be approached differently.
 
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Hi all! I'm new here and we're getting ready to start the process to get solar for our home, as both back-up for power failure and also powering some of what we use on the solar to reduce electric bills. We do not want a grid-tie as it provides little to no benefit for us, rather this will be a system we build as "off grid" that can also charge via AC power if needed.

Looking at our current usage, we want a system that we can expand over time, but have enough in place initially to cover our basic needs in the event of a power failure. Currently our usage is high (don't judge, it is what it is) at an average 74.5Kwh a day, or 2,236Kwh a month. Our peak use is 3,057Kwh in a month, our low use is 1,609Kwh in a month. I got these numbers by reviewing our 2020 usage, month by month.

I am looking to start with 2 BigBattery TREX (12.8Kwh) that will give us 25.6Kwh of power in batteries; they're 48V batteries. Over the next few years we'd likely look to expand that up to 102.4Kwh stored.

I'm trying to decide on whether I set up 2 MPP Solar LV2424 or 2 LVLV6048 controller/inverter boxes. I'm also trying to understand if I'd need to continue adding boxes in the future with additional batteries added over time.

I'm also trying to figure out our best option for solar panels...for our future needs, it's an insane amount of panels needed!

More importantly, I'm trying to figure out if the controller/inverter boxes can also have wind turbine energy as an input - where we live (central midwest) we have great sun from April to October, then consistent breezy wind from November to March, along with wind all year even in the summer months, especially when we're having our spring storms....so I'd like to look at options to add a wind turbine (or multiple turbines), but information is scant on how I can add that to a solar system to get power from both sun and wind. Does anyone have any good information on how to do this, or where I can look to better understand how to create a hybrid system.

What I've been looking at above is just the basics, I'm open to using different products if they're going to better meet our needs for our initial system and later expansion.

Thanks for your help!
Missouri Wind & Solar, I believe they have an “all in one” system than is just for wind and includes a turbine...pretty slick
Once we get our MPP solar up & running smoothly we intend to add wind?
 
You can't argue the fact that wind turbines are cool.

If you're laying in bed at night dreaming of a turbine, you're going to buy one anyway regardless of all the negatives everyone will tell you.

I've had my turbine for roughly a year, I'm using a brake to control it instead of a dump load (brakes at 28.7v/recovers at 27v). I've also got a 10w solar panel to trigger the brake relays when there is good sun available because because the turbine is virtually redundant when the sun is shining - it only runs during cloudy weather or night time.

My off grid stuff is a hobby, I'm not dependent on it. Through the course of my turbine learning curve I've come to the conclusion that if I was looking for value for money in the future, I would buy another battery or two to add to my bank. Solar is reliable, wind is not (unless you live in an area with constant wind). I like the sound of it when it gets spinning though, and my toddler is hypnotized by it.

A friend of mine lives near the sea and his turbine has put out around 9ah all day everyday for about 10 years.
 
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