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diy solar

Am I heading in the right direction?

twyche

New Member
Joined
Nov 5, 2022
Messages
12
Hello all,

I'm trying to develop a game plan to install a solar/battery backup system at our house. Below is an outline of my current thinking. Do you have any advice to help me along?

I want to create an expandable system that I can add on to as my budget allows. I don't want the system to be grid-tied and don't have interest in net-metering. The rules that our rural electric co-op have make a grid-tied system unappealing because of extra monthly fees and they limit the size of grid-tied systems.

In phase 1, I'd like to do is create a battery backup system for the critical loads in my house, but use the grid to charge the batteries (no solar panels in this phase) We occasionally have power outages that usually on last a few minutes to a few hours. The loads that I'd like to be able to run when the grid is down include our well water pump (1.5 hp, 280 ft below the surface), refrigerator, computer networking equipment, one room of lights and outlets (to keep cell phones and laptops charged) and the garage door opener.

Later in phase 2, I would like to be able to add additional backup battery capacity and solar panels to charge the batteries and run loads when the sun is shining.

In phase 3, I'd like to have the ability to charge an electric car (which I do not have yet).

Currently, I'm thinking using something like an EG4 6000 split phase low frequency inverter (to be able to start the well pump) and a couple of EG4 rack-mount batteries would help me accomplish the goals of phase 1.

A few questions: Do I have to make a critical loads subpanel or would something like the Lumin Smart Panel make sense? Why does Will's 48v solar system blueprint recommend a separate transfer switch? Don't the all-in-inverters such as the EG4 6000 include a transfer switch that will automatically kick in if the grid goes down?

Thank you for reading and offering any helpful advice.
 
Budget? Ability? Skill Level?

I am still a fan of DIY LFP batteries. Yes the cost of rack mount is coming down, but DIY is still less.
 
I want to create an expandable system that I can add on to as my budget allows. I don't want the system to be grid-tied and don't have interest in net-metering. The loads that I'd like to be able to run when the grid is down include our well water pump (1.5 hp, 280 ft below the surface), refrigerator, computer networking equipment, one room of lights and outlets (to keep cell phones and laptops charged) and the garage door opener.

Later in phase 2, I would like to be able to add additional backup battery capacity and solar panels to charge the batteries and run loads when the sun is shining.

In phase 3, I'd like to have the ability to charge an electric car (which I do not have yet).
OK, what you are describing here starts at BIG, and then goes to REALLY BIG. Please do not think you can just throw some stuff together to power this stuff.

My first suggestion is slow down and make an itemized list of what needs powering, and buy a clamp meter with "inrush current" capability so you know what your starting surges will be. Let's look at the first item you mention, the well pump. Here's a pump chart previously posted by another member Mike94550....
1667749040723.png
What you can see here is that a 1.5hp pump requires ~46A to start, which at 240V = 11,040W. I have no faith that a lower budget inverter like an EG4 can start such a load. I have a XW+6848, and the powers my 1hp pump flawlessly, but my starting surge is only 83% of your starting surge. The 6848 might power it, but the Outback Radian 8048 might be a better choice. Both the 6848, and the 8048 can be wired in parallel, so they both allow growth over time. They also allow for both generator or grid input without a transfer switch.

I like the 2X rule for powering stuff, meaning if your pump needs ~2800W to run (see chart), then have 2X the watts of panels, or ~5600W. Keep in mind that would be starting out at 5600W, but likely you will be working your way up from that once you try charging your car. Do you have the physical space to position 5000+W of panels?

Ultimately, I see this system growing to be in the 10,000W range, with a battery in the 1000Ah range. Right now, my primary system has 5500W online as of today, with a 570Ah battery. I have another 2000W of solar I plan on bringing online in the next few months, which will ultimately help greatly with late afternoon air-conditioning.

BTW, if you forget the well-pump and EV, then you could start out with a far smaller system. At my own place, keeping the lights and TV on, and the refrigerator running, I consume ~3.5kWh per day. If you targeted 5kWh as a reasonable consumption level for living a comfortable 21st century lifestyle, you could manage OK with a system with 1500-2000W of panels. Pair that with a 6000-7500W split-phase gasoline generator, and you should be able to get by just fine. Just use the inverter to keep the lights on and the refrigerator cold, and use the generator to pump water.
 
Budget? Ability? Skill Level?

I am still a fan of DIY LFP batteries. Yes the cost of rack mount is coming down, but DIY is still less.
Thanks for reading and responding. Under $10,000 for phase 1. I think I have the skill to do just about anything in this area that is being described in YouTube videos and the manufacturer's owner's manuals.

I started this journey thinking I was going to build my own powerwall from the cells up, but that's not where I want to spend my time. I like the features and form factor of the rack mount batteries.
 
OK, what you are describing here starts at BIG, and then goes to REALLY BIG. Please do not think you can just throw some stuff together to power this stuff.

My first suggestion is slow down and make an itemized list of what needs powering, and buy a clamp meter with "inrush current" capability so you know what your starting surges will be. Let's look at the first item you mention, the well pump. Here's a pump chart previously posted by another member Mike94550....
View attachment 119315
What you can see here is that a 1.5hp pump requires ~46A to start, which at 240V = 11,040W. I have no faith that a lower budget inverter like an EG4 can start such a load. I have a XW+6848, and the powers my 1hp pump flawlessly, but my starting surge is only 83% of your starting surge. The 6848 might power it, but the Outback Radian 8048 might be a better choice. Both the 6848, and the 8048 can be wired in parallel, so they both allow growth over time. They also allow for both generator or grid input without a transfer switch.

I like the 2X rule for powering stuff, meaning if your pump needs ~2800W to run (see chart), then have 2X the watts of panels, or ~5600W. Keep in mind that would be starting out at 5600W, but likely you will be working your way up from that once you try charging your car. Do you have the physical space to position 5000+W of panels?

Ultimately, I see this system growing to be in the 10,000W range, with a battery in the 1000Ah range. Right now, my primary system has 5500W online as of today, with a 570Ah battery. I have another 2000W of solar I plan on bringing online in the next few months, which will ultimately help greatly with late afternoon air-conditioning.

BTW, if you forget the well-pump and EV, then you could start out with a far smaller system. At my own place, keeping the lights and TV on, and the refrigerator running, I consume ~3.5kWh per day. If you targeted 5kWh as a reasonable consumption level for living a comfortable 21st century lifestyle, you could manage OK with a system with 1500-2000W of panels. Pair that with a 6000-7500W split-phase gasoline generator, and you should be able to get by just fine. Just use the inverter to keep the lights on and the refrigerator cold, and use the generator to pump water.
Thanks. Getting a clamp meter to measure inrush current is a good place to start. I started looking at the EG4 6000 after watching one of Will's videos
where he said that the this EG4 inverters will start well pumps. Perhaps I would need more than of the inverters in parallel to start my well pump. The EG4 6000 is a low frequency inverter with a built-in transformer that I thought is designed to start motors that require high inrush current.

I do have the physical space for a large south-facing ground mount array. (To use that space for a solar array I'll have to convince my wife as she has other plans for that space. Luckily the very old apple tree that was in the way, and that my family wouldn't let me cut down, got blown down in a wind storm!)

I have thought about a generator for just for the well pump. Two things cause me to hesitate: 1) storing and maintaining a supply of gasoline around the house and 2) wondering if my wife to able/comfortable starting the generator and throwing any necessary switches if I weren't around during a grid-down situation.

I definitely want to start out small and grow the system over time. I don't have an EV and have been getting by without a backup for the well pump for 6 years. So there no rush in finding a solution for that. I just want to ensure that the path I start out on will allow me to grow the system over time as my budget allows and not have to switch out major components of the system.

Thanks.
 
Thanks. Getting a clamp meter to measure inrush current is a good place to start. I started looking at the EG4 6000 after watching one of Will's videos
where he said that the this EG4 inverters will start well pumps. Perhaps I would need more than of the inverters in parallel to start my well pump. The EG4 6000 is a low frequency inverter with a built-in transformer that I thought is designed to start motors that require high inrush current.
Well, it's really a tough call. Here are the actual specs on your inverter from the EG website

  • High Surge Capacity (12KW for 1 second)
  • Overload Protection (5s @ 150% | 10s @ 110% to 150% Load)
Surging for 1 second is sort of better than other high-frequency AiOs, but not by much. Let's look for a moment at the spec for the Radian, and the XW-Pro. It's sort of an apples vs oranges kind of comparision. If you select 5 seconds as a standard, it looks like the Radian and XW can both surge to 12kW for 5 to 60 seconds, but the EG4 can only surge to 9000W for that time period.

So, you are on your own here in terms of whether or not it will power YOUR pump. I can not tell you how long a surge is needed to start your pump, but I can tell you that my XW very definately starts my pump. I guess you'll have to report back once you have it all hooked up, and press start. It might be of great value to call the company with your clamp meter measurements, and talk to each company engineer as to how it would go.

1667771629145.png1667771757498.png
 
Well, I'll start the default answer to these questions and we can work from there. Here's you To-Do list:

1: Power audit! This will give you some important information on how big your inverter needs to be as well as how much battery capacity you'll need. There is a link in the FAQ section (I think, or someone here will post it shortly) so fill in the blanks and see what it comes up with. You'll probably need some sort of Kill-A-Watt to get accurate measurements. Are you going to be running a 12v system? 24v system? 48v system? What are the specs on your solar panels? VoC? Vmp? Being as this is a new build, throw together a wish list of what you want and estimate on the high side.

1a: Where do you live? Speccing out a system for Scotland is a LOT different numbers than Arizona due to the amount of light you actually get. Someone here can post the link to the PVwatts.com or JCR Solar Uber-Sun-Hours calculator sites to help figure out how much you'll have to work with. That will be a box in the Power Audit form.

2: Parts list: You don't need a make & model list, just a parts list to start from for reference. You'll need an inverter, a MPPT charge controller, fuses, shunt, buck converter, batteries, wire, etc. Once you have a basic list it can be fine tuned to make & models after that. If you're looking at the All-In-Ones check for correct voltage outputs (120v or 240v Split Phase for North America, 220v Single Phase for European type areas) and make sure it has enough capacity for a little bit of growth and fudge factor.

3: Budget!: Steak is great but doesn't mean anything if your wallet says hamburger. :) Figure out what you're able to spend now vs what you'll have to cheap out on now and upgrade later.

4: Tape measure! Figure out where you're going to stick all the stuff you'll need. A dozen 3000AH batteries sounds great until you're sleeping on the floor because there's no room left for a bed. Is there a compartment that can house all this stuff? Will the server rack batteries fit? Are you going to have to make space? Physics can be pretty unforgiving.

5: Pencil out what you think you need and throw it at us so we can tell you what you've missed (because we ALL miss stuff the first go-round :) ) and help figure out which parts and pieces you're going to want to get.

Well that's the thing about solar systems, there is no 1-Size-Fits-All answer. Your system will need to be designed to fit YOUR needs. When you design and built the system, it's not going to be the perfect system for me, or Will or 12vInstall or anyone else, but it Will be the right system for You and that's the goal.

As for where to get started, let me throw my standard blurb in here to help point you in the right direction. There's going to be a lot of math and research involved, but that's going to be a LOT cheaper than just buying parts off of someone's list and finding out that it doesn't do what you need.

Don't panic on the Power Audit, you'll actually be doing that a few times. When you do the first pass put in ALL the Things that you might want. AirCon? Sure. Jacuzzi? Why not. MargaritaMaster-9000? Go for it.

The second pass will be the "I Absolutely Need This To Survive" list that isn't going to have much on there.

The third pass will be the "This is what is realistic" audit that you'll use to design the rest of the system.

The Power Audit is going to tell you 3 primary things: 1: How big does your inverter need to be to power your loads? 2: How much battery bank do you need to last $N number of days with krappy weather? and 3: How much solar panel will I need to install to refill those batteries in a 4 hour day (the average usable sun hours rule-of-thumb).

Once you know what you Want and what you Need and what your budget can Afford there will be somewhere in that Venn diagram where those three things meet.

After that, THEN you can start looking at parts.

Yes, it's a long drawn out process, but it's worth it in the end. Not every house has the exact same floorplan, not every vehicle is the same make & model, and not every solar system is designed the same.
 
Well, it's really a tough call. Here are the actual specs on your inverter from the EG website

  • High Surge Capacity (12KW for 1 second)
  • Overload Protection (5s @ 150% | 10s @ 110% to 150% Load)
Surging for 1 second is sort of better than other high-frequency AiOs, but not by much. Let's look for a moment at the spec for the Radian, and the XW-Pro. It's sort of an apples vs oranges kind of comparision. If you select 5 seconds as a standard, it looks like the Radian and XW can both surge to 12kW for 5 to 60 seconds, but the EG4 can only surge to 9000W for that time period.

So, you are on your own here in terms of whether or not it will power YOUR pump. I can not tell you how long a surge is needed to start your pump, but I can tell you that my XW very definately starts my pump. I guess you'll have to report back once you have it all hooked up, and press start. It might be of great value to call the company with your clamp meter measurements, and talk to each company engineer as to how it would go.

View attachment 119352View attachment 119353
Thank you. I will add this to my list of components to consider.
 
Well, I'll start the default answer to these questions and we can work from there. Here's you To-Do list:

1: Power audit! This will give you some important information on how big your inverter needs to be as well as how much battery capacity you'll need. There is a link in the FAQ section (I think, or someone here will post it shortly) so fill in the blanks and see what it comes up with. You'll probably need some sort of Kill-A-Watt to get accurate measurements. Are you going to be running a 12v system? 24v system? 48v system? What are the specs on your solar panels? VoC? Vmp? Being as this is a new build, throw together a wish list of what you want and estimate on the high side.

1a: Where do you live? Speccing out a system for Scotland is a LOT different numbers than Arizona due to the amount of light you actually get. Someone here can post the link to the PVwatts.com or JCR Solar Uber-Sun-Hours calculator sites to help figure out how much you'll have to work with. That will be a box in the Power Audit form.

2: Parts list: You don't need a make & model list, just a parts list to start from for reference. You'll need an inverter, a MPPT charge controller, fuses, shunt, buck converter, batteries, wire, etc. Once you have a basic list it can be fine tuned to make & models after that. If you're looking at the All-In-Ones check for correct voltage outputs (120v or 240v Split Phase for North America, 220v Single Phase for European type areas) and make sure it has enough capacity for a little bit of growth and fudge factor.

3: Budget!: Steak is great but doesn't mean anything if your wallet says hamburger. :) Figure out what you're able to spend now vs what you'll have to cheap out on now and upgrade later.

4: Tape measure! Figure out where you're going to stick all the stuff you'll need. A dozen 3000AH batteries sounds great until you're sleeping on the floor because there's no room left for a bed. Is there a compartment that can house all this stuff? Will the server rack batteries fit? Are you going to have to make space? Physics can be pretty unforgiving.

5: Pencil out what you think you need and throw it at us so we can tell you what you've missed (because we ALL miss stuff the first go-round :) ) and help figure out which parts and pieces you're going to want to get.

Well that's the thing about solar systems, there is no 1-Size-Fits-All answer. Your system will need to be designed to fit YOUR needs. When you design and built the system, it's not going to be the perfect system for me, or Will or 12vInstall or anyone else, but it Will be the right system for You and that's the goal.

As for where to get started, let me throw my standard blurb in here to help point you in the right direction. There's going to be a lot of math and research involved, but that's going to be a LOT cheaper than just buying parts off of someone's list and finding out that it doesn't do what you need.

Don't panic on the Power Audit, you'll actually be doing that a few times. When you do the first pass put in ALL the Things that you might want. AirCon? Sure. Jacuzzi? Why not. MargaritaMaster-9000? Go for it.

The second pass will be the "I Absolutely Need This To Survive" list that isn't going to have much on there.

The third pass will be the "This is what is realistic" audit that you'll use to design the rest of the system.

The Power Audit is going to tell you 3 primary things: 1: How big does your inverter need to be to power your loads? 2: How much battery bank do you need to last $N number of days with krappy weather? and 3: How much solar panel will I need to install to refill those batteries in a 4 hour day (the average usable sun hours rule-of-thumb).

Once you know what you Want and what you Need and what your budget can Afford there will be somewhere in that Venn diagram where those three things meet.

After that, THEN you can start looking at parts.

Yes, it's a long drawn out process, but it's worth it in the end. Not every house has the exact same floorplan, not every vehicle is the same make & model, and not every solar system is designed the same.
Thanks. No panic here on doing a power audit. That is a good idea. It should be fun. I already have The Energy Detective that monitors 16 circuits in my house. I also have a Kill-A-Watt. As @MichaelK suggested, I will get a clamp meter to measure inrush and I'll be off to the races to do my audit.

I live in Montana and have checked out PVwatts a few times to estimate what a solar system could produce for me. I will continue to do research and will come back with a parts list and budget to accomplish my goals in each of the 3 phases that I originally posted. Currently, I'm looking at 48V all-in-one 240 split phase systems.

Does anyone have thoughts on some of the other questions I originally posted such as critical load subpanel vs a load control systems like Lumin Smart Panel? Or, the need for a separate transfer switch vs whatever switching capabilities are built into all-in-one inverters?

Thanks again.
 
Thanks. No panic here on doing a power audit. That is a good idea. It should be fun. I already have The Energy Detective that monitors 16 circuits in my house. I also have a Kill-A-Watt. As @MichaelK suggested, I will get a clamp meter to measure inrush and I'll be off to the races to do my audit.

I live in Montana and have checked out PVwatts a few times to estimate what a solar system could produce for me. I will continue to do research and will come back with a parts list and budget to accomplish my goals in each of the 3 phases that I originally posted. Currently, I'm looking at 48V all-in-one 240 split phase systems.

Does anyone have thoughts on some of the other questions I originally posted such as critical load subpanel vs a load control systems like Lumin Smart Panel? Or, the need for a separate transfer switch vs whatever switching capabilities are built into all-in-one inverters?

Thanks again.
The only thing I would consider is the ability to parallel inverters.

I know growatt Cannot parallel.
I know Sol-Ark can.

Other manufacturers you will have to ask or find out.

The reason I say this is because of how your going about it.

Little bit at a time.

If you don’t want to be buying a new inverter every time you go up in power usage I suggest getting something you can just add to to meet your current or projected power needs.
 
2 things.

My Schneider Conext SW 4024 4000 watt inverter will start my 3/4 hp well pump all day long, every day and has for the past 4 years.

But it has locked me in because while it was stackable when I bought it, Schneider has discontinued that feature, so the SW is no longer stackable.

If you're dealing with inductive loads, you'll probably want a low frequency inverter like the XW, which I have no doubt will start anything you throw at it.

The thing you'll need to balance and decide on is how much idle current draw is acceptable to you. The cheap low frequency inverters have hi idle current. The top tear gear like Schneider and Outback have very well low idle current.
 
I just installed a Growatt 12kw low frequency inverter for my daughter's off grid farm. It's a low frequency inverter but not stackable. But their plan is a second separate system if the out grow 12kw.

But the growatt has a idle draw of about 140 watts. That's over 3300 watts per day.

Solution? A few extra panels and maybe an extra battery

My SW low frequency draws between 11 and 30 watts idle . XW is about that give or take.
 
The only thing I would consider is the ability to parallel inverters.

I know growatt Cannot parallel.
I know Sol-Ark can.

Other manufacturers you will have to ask or find out.

The reason I say this is because of how your going about it.

Little bit at a time.

If you don’t want to be buying a new inverter every time you go up in power usage I suggest getting something you can just add to to meet your current or projected power needs.
Yes. I'm definitely looking for all-in-one inverters that can be connected in parallel. The EG4 6000 can be paralled up to 9 units for a 54 Kw system.
 
I just installed a Growatt 12kw low frequency inverter for my daughter's off grid farm. It's a low frequency inverter but not stackable. But their plan is a second separate system if the out grow 12kw.

But the growatt has a idle draw of about 140 watts. That's over 3300 watts per day.

Solution? A few extra panels and maybe an extra battery

My SW low frequency draws between 11 and 30 watts idle . XW is about that give or take.
Does your daughter have a deep well pump that the Growatt can start and run?
 
We will be putting a well in soon but I doubt it will be a deep well here in FL. But I do know the growatt will start my 3 ton heat pump no problem.
 
My Schneider Conext SW 4024 4000 watt inverter will start my 3/4 hp well pump all day long, every day and has for the past 4 years.

But it has locked me in because while it was stackable when I bought it, Schneider has discontinued that feature, so the SW is no longer stackable.
You know, I bought my Conext 4024 for exactly the same reason. The 2017 version was supposed to be parallelable. Fast forward to 2022 and I find out that is no longer supported. DAMN!!!!!

The good news though is that my single 4024 has performed admirally, powering all my workshop loads, including a 1.6hp air-compressor, so it hasn't yet been an issue. I did want a backup for my XW+ that runs the well-pump, but I guess I can fall back on the generator.
 
You know, I bought my Conext 4024 for exactly the same reason. The 2017 version was supposed to be parallelable. Fast forward to 2022 and I find out that is no longer supported. DAMN!!!!!

The good news though is that my single 4024 has performed admirally, powering all my workshop loads, including a 1.6hp air-compressor, so it hasn't yet been an issue. I did want a backup for my XW+ that runs the well-pump, but I guess I can fall back on the generator.
Yeah I got no complaints. The SW is a beast

After installing a growatt, I've got a lot more appreciation for the top tier brands R&D and software.
 
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