Just getting started and I have a few questions.

[tacomaguy20]

I've been reading and watching videos and I'm not sure exactly what would be the best option for me. I haven't bought anything yet, still trying to figure out what I need. I currently live in Phoenix AZ and my power usage is about 16000 kwh per year according to SRP (power company). Most of that power usage comes in the summer from my air conditioning so my power usage fluctuates quite a bit between the summer and winter. SRP shows me the monthly, daily, and even hourly usage and I'm not sure what numbers to base my potential solar system on? Additionally, I believe the city requires me to be tied into the grid so I'm not sure if I can use an off grid system in conjunction with my grid tie in. I guess it's illegal (sort of)? I was considering the off grid blueprints for the two 6500ex inverters above and it sounds like it can be legal under certain circumstances? So hopefully someone can help me figure a few things out. I've put a few questions below that I've been wondering.

1. Is off grid doable and still be tied in some way to the grid? Or should I be looking at a grid tie in system or a hybrid? I do know the difference but I'm not familiar enough with the ins and outs of connecting to my electrical grid and I'm not sure if I am allowed to DIY a grid tie in system. I am familiar with electric in general however. I'd like something I could slowly add to over time to reduce initial costs. Add more panels, add more batteries, etc. and not sure if that matters depending on system.

2. Would it be wise to get a few quotes from local companies to see what they recommend 1st? The cost is a deterrent for me which is why I probably would prefer to do it myself.

3. Should I just take my average monthly usage of 1350 kwh or should I look at my max summertime usage of 2700 kwh to estimate the size of system I need?

4. I was thinking of placement in my garage (on the opposite side of my Electrical panel) but summertime in AZ gets hot and the garage isn't air conditioned. Is that a problem?

 

[12VoltInstalls]

SRP shows me the monthly, daily, and even hourly usage and I'm not sure what numbers to base my potential solar system on

Do you want or even have the option to “sell back” to the grid? That is the start of the answer.

1. Is off grid doable and still be tied in some way to the grid? Or should I be looking at a grid tie in system or a hybrid?

The above question is what this answer will be derived from.

Would it be wise to get a few quotes from local companies to see what they recommend 1st? The cost is a deterrent for me which is why I probably would prefer to do it myself.

Installers: virtually any established installers can give you a workable system. Two issues, though: 1) might not be what you actually want or need; 2) is going to be ~2.x-6 times the cost of DIY and an electrician. Sometimes even more but from what I’ve seen triple the cost of DIY is common.

Should I just take my average monthly usage of 1350 kwh or should I look at my max summertime usage of 2700 kwh to estimate the size of system I need?

Is your goal:

• To save money on electricity bill?
• To be “greener?”
• To have a system that works if grid is down?
• To just offset the high-demand summer months?
• To skew time-of-use charges in your favor?

Basically your goals and your budget in dollars should be established first, and then see what the equipment costs are to maximize the kWh in accomplishing your goals and compare that to your budget.

For example, to cover 100% of your usage with solar you would use the max daily kWh from the summer air conditioner months.

1. Is off grid doable and still be tied in some way to the grid?

Yes

4. I was thinking of placement in my garage (on the opposite side of my Electrical panel) but summertime in AZ gets hot and the garage isn't air conditioned. Is that a problem?

heat can be a factor to consider. You may not want to use the garage if it heat soaks to 130*F for example.

 

[tacomaguy20]

Do you want or even have the option to “sell back” to the grid? That is the start of the answer.

Ideally, yes.

Installers: virtually any established installers can give you a workable system. Two issues, though: 1) might not be what you actually want or need; 2) is going to be ~2.x-6 times the cost of DIY and an electrician. Sometimes even more but from what I’ve seen triple the cost of DIY is common.

Yeah I'm not looking to use them, I was thinking of getting a quote just to get an idea of where they would suggest I install the inverter, place the panels, that kind of thing.

Is your goal:

• To save money on electricity bill?
• To be “greener?”
• To have a system that works if grid is down?
• To just offset the high-demand summer months?
• To skew time-of-use charges in your favor?

Basically your goals and your budget in dollars should be established first, and then see what the equipment costs are to maximize the kWh in accomplishing your goals and compare that to your budget.

My goal is to shrink or eliminate my electric bill in such a way that it's cost effective (meaning I don't pay for 20 years on a solar system). I'd like to recoup my investment in 5 to 7 years ideally. I'd also like to have backup for when the grid goes down. My power company charges 36 dollars a month just to have solar (for grid maintenance or whatever) but they do have the ability to sell back to the grid and they have higher costs at specific times of the day for on peak usage (especially in the summer).

So basically if I get off grid system and just use the grid for backup and/or charging my batteries, I can get a cheap inverter setup and buy whatever batteries I want (pretty much). This seems like a cheap customizable option but I can't sell back to the grid and will pay a minimum of that service charge + extra usage every month.

If I get an on grid system with battery backup, the inverter costs are cheap but from what I understand is they require specific batteries which are really expensive (Growatt, for example). But this would allow me to sell back to the grid, possibly earning enough credit to make that service charge worth it.

If I choose a hybrid system, it would allow for the most flexibility where I can sell back to the grid and buy whatever batteries I want but the initial inverter costs are high.

I've been trying to find if there is a good grid tied option similar to growatt where I can use whatever batteries I would like. That would reduce my inverter cost and battery costs both.

For example, to cover 100% of your usage with solar you would use the max daily kWh from the summer air conditioner months.

Thanks.

heat can be a factor to consider. You may not want to use the garage if it heat soaks to 130*F for example.

I'm not sure how hot my garage gets in the summer. I'll have to start monitoring. My garage isn't completely sealed to allow for venting but in the summer we can reach about 120 outside (although that's probably the summer high).

 

[50ShadesOfDirt]

Yes, you can have as much of an off-grid system as you want, even though currently on-grid.

Basically, you build a partial (inverter + battery-bank + charger) or an entire off-grid system (same + mppt + solar panels), and run it *in parallel* to the grid system. The only tie would be using the grid power to recharge the battery-bank via "shore power" concept ... your off-grid equipment can draw from the grid to make up power, if needed.

Any kW's derived from your off-grid system and used by house devices are kW money not given to the grid. AHJ/codes/electrician effort might be much simpler, as such a system will never "back-feed" the grid.

Throw a switch this way, and the house is fed with off-grid power ... throw it that way, and you are back on grid power. You could also envision using off-grid power during the day, when grid power is expensive, and then reverse it at night when grid power is less expensive. This might reduce the size of the off-grid system, or cut out components.

The utility folks charging you X dollars per month is ok, because you'll treat that as the cost of having a complete backup for your off-grid system, and they maintain this for you. Compare to a fuel generator backup, and fuel, and maintenance, etc. when applied to someone who is completely off-grid.

You can start very small, and test the concept ... an AIO inverter, and a battery-bank, some electrician work, and done ... draw on this off-grid parallel part during the day, flip to grid power at night while battery-bank is recharging on less expensive power. Add in other solar componentry as time & money permit.

To start some of the design process:

1. Go here, and enter in each appliance's values (watts, hours/day you want to run it, etc.):
unboundsolar.com/solar-information/offgrid-calculator

2. Go here, using numbers from above, and fiddle with various entries/components, and you'll see in real-time what your system component (inverter, mppt, panel) sizing is:
altestore.com/store/calculators/off_grid_calculator

There are many similar website pages/calculators, but these two pages should help you get through most of the necessary calculations. This helps you quickly decide if you can do what you want to do, and you can vary component choices for what-if scenarios.

Hope this helps ...

 

[EastTexCowboy]

My goal is to shrink or eliminate my electric bill in such a way that it's cost effective (meaning I don't pay for 20 years on a solar system). I'd like to recoup my investment in 5 to 7 years ideally. I'd also like to have backup for when the grid goes down. My power company charges 36 dollars a month just to have solar (for grid maintenance or whatever) but they do have the ability to sell back to the grid and they have higher costs at specific times of the day for on peak usage (especially in the summer).

So basically if I get off grid system and just use the grid for backup and/or charging my batteries, I can get a cheap inverter setup and buy whatever batteries I want (pretty much). This seems like a cheap customizable option but I can't sell back to the grid and will pay a minimum of that service charge + extra usage every month.

If I get an on grid system with battery backup, the inverter costs are cheap but from what I understand is they require specific batteries which are really expensive (Growatt, for example). But this would allow me to sell back to the grid, possibly earning enough credit to make that service charge worth it.

If I choose a hybrid system, it would allow for the most flexibility where I can sell back to the grid and buy whatever batteries I want but the initial inverter costs are high.

I've been trying to find if there is a good grid tied option similar to growatt where I can use whatever batteries I would like. That would reduce my inverter cost and battery costs both.


I'm not sure how hot my garage gets in the summer. I'll have to start monitoring. My garage isn't completely sealed to allow for venting but in the summer we can reach about 120 outside (although that's probably the summer high).

With the minimal information provided it's just a educated guess, but if you want to eliminate your electric bill or get close, and also have battery backup, it's going to be a challenge to build something like that and recoup the investment in 7 years. I'd recommend using some of the resources available on this forum and other places to educate yourself on the various systems. This will help you make good decisions whether you DIY or pay someone to do it. There are several resources which can help you figure out what you need.

I think you have a misconception on off grid systems. The "cheap inverter and whatever batteries I want" isn't really how it works. For starters, whether it's off grid or hybrid doesn't matter to the batteries. You can go with less expensive "up front" FLA batteries but they aren't really cheaper over time. You need more FLA kWh storage to get the same results as LifePO4 because the max discharge on the FLA is 50% whereas the lithium can be discharged to 80% or even more. And there really aren't any "cheap" batteries. You can save some money by building your own with raw cells, but the price difference there is less than it once was.

On the garage thing, I have mine in the garage here in Texas where we get a little heat in the summer. I installed a mini-split on the garage to manage the temps. It's not a very cost effective solution but it isn't terrible and there aren't many options if you're going to go the garage route.

Hope this helps.

 

[SamDeleted]

And there really aren't any "cheap" batteries.

Well you say that , I just paid £0.086p per usable KW for ex UPS AGM batteries

If you shop around there's some great deals out there

 

[EastTexCowboy]

Well you say that , I just paid £0.086p per usable KW for ex UPS AGM batteries

If you shop around there's some great deals out there

True. There are some options. But I feel like for someone who is just getting their feet wet it's a good idea to either stick with the basics or do more research and ask a lot of questions. Either way, the batteries don't care whether you are off-grid or grid tied.

 

[tacomaguy20]

With the minimal information provided it's just a educated guess, but if you want to eliminate your electric bill or get close, and also have battery backup, it's going to be a challenge to build something like that and recoup the investment in 7 years. I'd recommend using some of the resources available on this forum and other places to educate yourself on the various systems. This will help you make good decisions whether you DIY or pay someone to do it. There are several resources which can help you figure out what you need.

I think you have a misconception on off grid systems. The "cheap inverter and whatever batteries I want" isn't really how it works. For starters, whether it's off grid or hybrid doesn't matter to the batteries. You can go with less expensive "up front" FLA batteries but they aren't really cheaper over time. You need more FLA kWh storage to get the same results as LifePO4 because the max discharge on the FLA is 50% whereas the lithium can be discharged to 80% or even more. And there really aren't any "cheap" batteries. You can save some money by building your own with raw cells, but the price difference there is less than it once was.

On the garage thing, I have mine in the garage here in Texas where we get a little heat in the summer. I installed a mini-split on the garage to manage the temps. It's not a very cost effective solution but it isn't terrible and there aren't many options if you're going to go the garage route.

Hope this helps.

Well the point about the batteries was I wasn't exactly wanting to go cheap but I didn't want proprietary batteries. I wanted to start off with a few and add more over time. I didn't want a bank that had a specific size or that I couldn't expand upon. From what I understand is that only hybrid or off grid systems let me add whatever batteries I want and also allow for adding more later over time. If that is incorrect, please direct me to an grid tied system that allows for me to use whatever batteries I want. Growatt seems to make a grid tied inverter with a specific battery bank. I believe I'm limited on battery choices unless I buy their off grid system, which doesn't seem to have the same limitation. Unless I'm completely misunderstanding.... but that seems to be the case as far as I've read.

As far as doing the solar install myself, I'm looking at systems (hybrid that I could buy for $5600 (EG4 18/12), used panels over at santan, let's just say 30 to 40 for $1500 to $2000, and batteries (probably just a couple to get me started, lets say the lifePo4 2 at $3000). So let's round to 11,000. I'm sure it would be more with panel racking/wiring. But if I can reduce the majority of my electric costs, I figure I could save myself 1500+ dollars a year off my electric, maybe more because I could sell back to the grid. Now that's a little over 7 years to pay for itself. However, if I buy the growatt off grid inverter instead ($2000, instead of $5600 for the hybrid), and just run it as grid connected (instead of grid tied), that would reduce my cost down to 7000, which I'm pretty sure would pay for itself rather quickly. Additionally, if I went grid tied, the other growatt inverter I was looking at was even cheaper ($1500) but I think I'm limited by the battery bank. Once again let me know if I'm wrong on that point. So an all in one system for about somewhere between 6500 and 11,000 (probably slightly more) but then that's not factoring in the tax credits. So am I really that far off from 5 to 7 years to recoup my investment?

 

[tacomaguy20]

True. There are some options. But I feel like for someone who is just getting their feet wet it's a good idea to either stick with the basics or do more research and ask a lot of questions. Either way, the batteries don't care whether you are off-grid or grid tied.

Please tell me which inverters allow for grid tied using whichever batteries I want. Oh to clarify, I'm in the US. I haven't been able to find the size I want for an on-grid 11Kw system (or higher) without specific battery limitations. Everything seems to be off grid or hybrid.

 

[EastTexCowboy]

Please tell me which inverters allow for grid tied using whichever batteries I want. Oh to clarify, I'm in the US. I haven't been able to find the size I want for an on-grid 11Kw system (or higher) without specific battery limitations. Everything seems to be off grid or hybrid.

Let's start with some basics. When we talk about inverters a lot of the discussion is actually around AIO units, such as the EG4 you mentioned. These have the inverter, charge controller, and transfer switch all built into one unit. This generally makes it simpler for DIY but there are advantages to component built systems. There are a number of threads on here which discuss this. I'm going to assume AIO for this discussion.

When you say you want an on-grid 11kw system or higher, are you referring to the inverter capacity or the solar panel output? It sounds like inverter capacity but just want to be sure.

The question on "whichever batteries you want" - Assuming the inverter allows you to configure the battery type, which many if not most do nowadays, you can pretty much use any battery you want and the system will function. If you want the inverter to directly communicate with the batteries then you'll need to make sure the inverter you choose is compatible with the batteries you choose. I don't see this as a major issue either way. I have EG4 batteries and MPP inverters. I use Solar Assistant to monitor both and it works well. So effectively you can use whatever battery you want and add more whenever you want. Where you can encounter issues is if you don't have enough battery to support the load when you're running on battery only.

You state that everything you're finding has specific battery limitations. Can you clarify and maybe point to a specific model of on-grid inverter which has battery limitations? Generally speaking, the inverter is just going to charge the battery bank until it's fully charged. It doesn't care if it's a 20kWh bank or a 120kWh bank. Other than the battery/inverter communication thing, or not enough batteries to support the load, there are a lot of options for batteries. We have folks on here running grid-tied systems with LifePO4, FLA, AGM, EV batteries, forklift batteries - it's pretty wild west. You just need to know what you're doing to build it.

Maybe someone else can jump in here and provide some input and clarification on anything I'm missing.

 

[tacomaguy20]

Let's start with some basics. When we talk about inverters a lot of the discussion is actually around AIO units, such as the EG4 you mentioned. These have the inverter, charge controller, and transfer switch all built into one unit. This generally makes it simpler for DIY but there are advantages to component built systems. There are a number of threads on here which discuss this. I'm going to assume AIO for this discussion.

When you say you want an on-grid 11kw system or higher, are you referring to the inverter capacity or the solar panel output? It sounds like inverter capacity but just want to be sure.

The inverter capacity. I estimated that my average usage would require a 9kw system but I'd rather go larger just in case.

The question on "whichever batteries you want" - Assuming the inverter allows you to configure the battery type, which many if not most do nowadays, you can pretty much use any battery you want and the system will function. If you want the inverter to directly communicate with the batteries then you'll need to make sure the inverter you choose is compatible with the batteries you choose. I don't see this as a major issue either way. I have EG4 batteries and MPP inverters. I use Solar Assistant to monitor both and it works well. So effectively you can use whatever battery you want and add more whenever you want. Where you can encounter issues is if you don't have enough battery to support the load when you're running on battery only.

You state that everything you're finding has specific battery limitations. Can you clarify and maybe point to a specific model of on-grid inverter which has battery limitations? Generally speaking, the inverter is just going to charge the battery bank until it's fully charged. It doesn't care if it's a 20kWh bank or a 120kWh bank. Other than the battery/inverter communication thing, or not enough batteries to support the load, there are a lot of options for batteries. We have folks on here running grid-tied systems with LifePO4, FLA, AGM, EV batteries, forklift batteries - it's pretty wild west. You just need to know what you're doing to build it.

Maybe someone else can jump in here and provide some input and clarification on anything I'm missing.

So as a new poster, I wasn't up to speed on UL9540 requirements for grid tied systems so when looking at off grid setups, people were using the LifePO4 batteries, but for on grid setups, they were using battery banks and proprietary setups. Specifically I was looking at the growatt inverter. Turns out those battery banks are UL9540 certified to work with the inverter, other batteries are not. It turns out that my system will need to be grid tied and comply with UL9540 as well as UL1741, UL1741SA and IEEE 1547. I could possibly hook up an off grid setup but not sure I'd want to risk having an unapproved system and I wouldn't be able to sell back to the grid.

 

[EastTexCowboy]

That makes a little more sense to me. I think @SignatureSolarJames mentioned that the EG4 18K is going to be tested for 9540 soon. You mentioned it earlier. There's also So-Ark or if you're willing to do components Victron is solid. I'd say reach out to SS and get confirmation on the EG4 and maybe their recommendations on battery pairing. Dexter at Current Connected might be a good resource for you as well - @HighTechLab.

 

[cs1234]

Victron is a no go in the states if you require UL9540 as far as I know at the moment.

 

[tacomaguy20]

That makes a little more sense to me. I think @SignatureSolarJames mentioned that the EG4 18K is going to be tested for 9540 soon. You mentioned it earlier. There's also So-Ark or if you're willing to do components Victron is solid. I'd say reach out to SS and get confirmation on the EG4 and maybe their recommendations on battery pairing. Dexter at Current Connected might be a good resource for you as well - @HighTechLab.

I was looking at the Sol-Ark and I'm thinking the EG4-18k is more in my budget range (if it works as it's supposed to) with the combination of EG4 batteries because they are a lot less expensive. I was actually thinking that the Growatt 11.4kW Grid-Tie Inverter | MIN11400TL-XH-US would work for what I want to do but the battery that's UL9540 certified to go with it is ridiculously expensive. The inverter is $1600 but the battery is about $7800 for 9.9KWh. Or I could buy the EG4 18k for $5600, get slightly more output, and pair it with 2 EG4 batteries (which I think it will be UL9540 certified with) for $3000 at 10.25 KWh and easily expand that battery bank one at a time for $1500 dollars when I decide to get more storage. I really wish the EG4 batteries were certified with Growatt and it would solve my issue. I'd be able to get an inverter and 2 battery system for around $4,600. I suppose I could install the system with no batteries and add them stealthily later but I'd rather do everything on the up and up if possible.

 

[SignatureSolarJames]

I would talk to your inspector personally and ask hime what points he is looking for to authorize a system so you can make it pain free for him.

 

[tacomaguy20]

I would talk to your inspector personally and ask hime what points he is looking for to authorize a system so you can make it pain free for him.

Yeah I plan on it. The city has a package deal where I can pay for additional inspections up front in case I don't pass the first or even second inspection. The issue is I'm still in the design phase and I'd like to get all my ducks in a row before purchasing anything. I was also considering an AC coupled system with one grid tied inverter and 1 off grid inverter but I'm not sure how the inspector would feel about that. My utility company said even "grid connected" wasn't approved but not sure if AC coupled would apply. Maybe I can get an inspector on the phone and ask.

 

[SignatureSolarJames]

The phone call that is all about saving the inspector time is a good ploy to get in their head and have them help you help them. I always say the regulator is the regulation lol