I have no experience and don't know where to start. I would like to do a full off grid system.

[Wrivera]

Hello,

I have no experience, and my only knowledge of solar is watching some videos. And found this forum which seems like there are many very helpful people here.

I am currently in the process of building a large garage (2,000SF) in which I will have a full bathroom and I plan on conditioning a portion of it for temporary living while I build a small house for my family.

With that said I will also need enough power for the house as well in the future. I am very open to suggestions on how to accomplish all this but I will explain what I would like to do.

I am hoping to have at least 100 amps for the garage and run a 200 amp sub panel to the house once it is built. The garage will be where the inverters and batteries are located.

Few questions:

• Is it possible to produce 300-400amps of power by a fully off grid system?
• If so, is it feasible on a reasonable budget?
• What are some good first steps to achieving what I am looking for?

Thanks in advance!

 

[Craig]

Anything is possible with enough money. For that much power I would look into Sol-Ark inverter/chargers. You can get panels from santan solar in Arizona for less than 50 cents a watt. What us going to be important is how much of that power will you be using for a prolonged period dobyou need 400 amps at how many volts for how long. That's what is going to tell you what you really need.what are you using all that power for?

 

[Mattb4]

First off is to understand it is loads that drive the supply. Loads are rated in watts and watts over time (hour) is watt-hours or kWh if 1000wh.
Watts = Volts X Amps
So you will not be designing for amps but watt-hours.

So you need to spend some time figuring out your daily load requirements. Once you have a handle on that you can than work towards what you will need to supply that daily load. One thing that might help you is to look at your present electrical consumption from your electrical Bill. It should tell you how much you used last month.

 

[Rocketman]

Off grid is expensive, the larger the system the more costs rise. Conservation is vitally important! (Plan that in your build).

There are three big factors- how many watts you will use in a day, and how many watts you will use at once and how much is needed to get you through the night - until the sun rises again.

watts = volts * amps

Just because you have a 200amp panel doesn’t matter - the real question is how much is on and on at once.

 

[BentleyJ]

Welcome and hopefully we can help you. The very first thing to do is a comprehensive energy audit. Since its new construction there is no history on that structure but you do have a history in your current home with your lifestyle.
Using a spreadsheet make a list of all the major electric appliances, equipment in your garage, EV's, outdoor usage pool, spa etc. Decide if you want 100% whole house back up and or if critical loads panel would work.
For whole house its one list on the spreadsheet for a critical loads panel its 2 lists on the spreadsheet. One for critical appliances and the other for stuff you can live without for a while.

This is how you size a system properly, everything else is a guess. Usually an inaccurate one at that.

 

[Mattb4]

Building a solar setup that could produce 400a at 240vAC would be quite the undertaking. 96,000 watts. I wonder if SolArk or EG4 has a 100K AIO for sale?

 

[Hedges]

You can make a certain number of amps, e.g. a 4x Sunny island system like mine can deliver 23kW at 240Vrms (100A) continuous, at 25 degrees C.

It can also mange up to twice that, 48kW, of PV. This might deliver 200A 240V while the sun shines, depending on panel orientation.

Without sun you rely on batteries (or generator). How many kWh/day to you want? Batteries are expensive, so while 100A or 200A briefly is doable, no reasonable house would draw 24kW 24/7. You might need 0.5 ~ 1.0 MWh of batteries ...

Do you want single (split) phase, or 3-phase?

 

[Doggydogworld]

I am currently in the process of building a large garage (2,000SF) in which I will have a full bathroom and I plan on conditioning a portion of it for temporary living while I build a small house for my family.

As mentioned above the first thing is an energy audit. This page has some basics and a link to a sample spreadsheet you can download. This will drive your solar array and battery sizing.

Second thing to consider is maximum power load at a particular time. Service panel size is a very crude estimate of max power. Better to use the energy audit and add up all devices that might run at the same time. You can also decide if you can live with some devices "taking turns" to reduce max power. That info will drive inverter and back-up generator sizing.

Where in AZ are you? Unless at high elevation, e.g. Flagstaff, your #1 consumption by far will be air conditioning. There are ways to design your house (and garage) to reduce A/C consumption. That can greatly reduce the cost of your solar array and batteries. Insulation, radiant barriers, shading, window locations and coverings, thermal mass and so on.

You might consider a ground source heat pump aka geothermal heat pump. They can be reasonable or very costly, depending on soil conditions and local codes. You also might consider an Ice Bear 20 air conditioner. It's basically a "thermal battery", which may be cheaper than a LiFePO4 battery. Some things that don't make economic sense when you have cheap grid power suddenly become viable when you go off-grid.

Anything you can shift to gas/LP/wood/etc. will reduce your solar price tag. Space and water heating, clothes drying, cooking, etc. But then you have to pay for fuel, so it's a tradeoff.

 

[EastTexCowboy]

Off grid is expensive, the larger the system the more costs rise. Conservation is vitally important! (Plan that in your build).

There are three big factors- how many watts you will use in a day, and how many watts you will use at once and how much is needed to get you through the night - until the sun rises again.

watts = volts * amps

Just because you have a 200amp panel doesn’t matter - the real question is how much is on and on at once.

This

Having a 100a and/or 200a panel means very little when looking at actual real life usage. Figuring out that usage for a house you haven't built can be a challenge and ultimately is going to be an educated guess, but that's where you need to start. My house has two 200a panels. I'm running 80% of the house on solar right now (based on kwh usage) but the typical load on the solar portion with all the ACs and all the other stuff running, including 5 freezers, is around 20 amps. The highest spike I've seen was under 35 amps. Part of this is high efficiency AC and appliances, but as you can see it's nowhere close to the panel breaker size. On the flip side, I had a home many years ago with horribly inefficient loads and it would occasionally trip the 200a main. It's all about the load and as someone else mentioned, the load over time.

The good news is you'll find plenty of help here.

 

[Quattrohead]

Get an all-in-one that is stackable with more for the future, the EG 18K or Solark 15K are current good performing machines that are relatively easy to work with.
Start with maybe 7-10 KW of pv panels and 20 to 30 KW worth of battery and again especially with the batteries make sure you can add more of the same later on.
I am currently building a 100% off grid house with ICF, spray foam insulation and variable speed compressor HVAC system, hybrid water heater etc in Florida.

 

[Lord Doa]

Anything is possible with enough money.

My boss learned to stop asking if I could accomplish a task because me response was, "There's nothing IT can't do with a big enough budget." They now ask "How much do you need to accomplish this task" which is less fun to respond to

 

[ArtDeco]

First off is to understand it is loads that drive the supply. Loads are rated in watts and watts over time (hour) is watt-hours or kWh if 1000wh.
Watts = Volts X Amps
So you will not be designing for amps but watt-hours.

So you need to spend some time figuring out your daily load requirements. Once you have a handle on that you can than work towards what you will need to supply that daily load. One thing that might help you is to look at your present electrical consumption from your electrical Bill. It should tell you how much you used last month.

Since the O.P. is going to build, he should be able to get the figures he needs from all the appliances he plans to buy. If all electric there is a huge difference between heat pumps and an electric baseboard heat system with cheap electric water heater, etc. etc.

Even among energy star appliances there is a big difference . Then he can do some modeling. Use the models wisely ( they aren't Gospel, just better than guessing ). Don't use published averages.

Square footage of the house doesn't really matter.

 

[sunshine_eggo]

Welcome and hopefully we can help you. The very first thing to do is a comprehensive energy audit. Since it new construction there is no history on that structure but you do have a history in your current home with your lifestyle.
Using a spreadsheet make a list of all the major electric appliances, equipment in your garage, EV's, outdoor usage pool, spa etc. Decide if you want 100% whole house back up and or if critical loads panel would work.

+1000

@Wrivera

Link #1 in my signature.

 

[schmism]

You'll likely find that extremely high transient loads (like large welders or other shop equipment) is likely best served by just running an old fashion 240v generator during those use time. Bonus if you set it up to charge the battery bank when you turn it on to say run the welder etc.

AIO's offer parallel-abity which allows systems to be built/added on to that can reach into the 20Kw output and 30-40KW PV. Battery systems can be scaled as big as grid backup if you have the checkbook.

As an example, say you have 60a of 220v that needs to run for an hr at a time. you need an extra 13kw to do that. In solar world thats likely $30K worth of installed equipment. In the generator world a 20Kw diesel is $5k and $10K worth of diesel will get you a LONG way (and your only at half the solar cost for just that equipment load)

 

[ksmithaz1]

400A of 240v is an awful lot of electricity/demand. I can't imagine a garage and a "small house" needing that much. Are you wanting to run a couple of CNC's, with a few screw machines and other tooling all at the same time in your garage? Once you do an audit, unless you are planning to run a machine shop or something in your garage, I think you will find you don't really need that much. You should be able to build a small all-electric home under a 100A demand envelope. Small = 2000 sqft ish. If I was building new, I'l probably build out with a detached utility room for the solar/generator and run 150A capable service up to the house, then de-rate to 100 and see how it rolls. Two12K (50A) Sol-ARKS or EG4's will run it, add a third if you find the need to. If you are running a machine shop in the garage , I'd make the power-plant independent, in the same shed probably with another big AIO, and a manual cross connect, so you could take one system or the other offline for whatever reason and keep the HVAC and fridges running, share the generator, etc. I'd definitely start with a power-shed and fat conduit out to the building locations.

 

[Doggydogworld]

Square footage of the house doesn't really matter.

It can matter a lot in AZ, where OP lives. Air conditioning can dwarf all other loads combined. I'm in a big house in south TX and A/C is ~80% of my summer consumption.

 

[EastTexCowboy]

400A of 240v is an awful lot of electricity/demand. I can't imagine a garage and a "small house" needing that much. Are you wanting to run a couple of CNC's, with a few screw machines and other tooling all at the same time in your garage? Once you do an audit, unless you are planning to run a machine shop or something in your garage, I think you will find you don't really need that much. You should be able to build a small all-electric home under a 100A demand envelope. Small = 2000 sqft ish. If I was building new, I'l probably build out with a detached utility room for the solar/generator and run 150A capable service up to the house, then de-rate to 100 and see how it rolls. Two12K (50A) Sol-ARKS or EG4's will run it, add a third if you find the need to. If you are running a machine shop in the garage , I'd make the power-plant independent, in the same shed probably with another big AIO, and a manual cross connect, so you could take one system or the other offline for whatever reason and keep the HVAC and fridges running, share the generator, etc. I'd definitely start with a power-shed and fat conduit out to the building locations.

I think he's just looking at the main breaker capacities on the two panels. Based on the rest of the info I'm guessing he won't need anything out of the norm.

 

[sunshine_eggo]

It can matter a lot in AZ, where OP lives. Air conditioning can dwarf all other loads combined. I'm in a big house in south TX and A/C is ~80% of my summer consumption.

Arizona has multiple climate zones. Heat might be a larger concern.

 

[ksmithaz1]

It can matter a lot in AZ, where OP lives. Air conditioning can dwarf all other loads combined. I'm in a big house in south TX and A/C is ~80% of my summer consumption.

80% seems a little high, yellow is HVAC green is everything. Last week, the mean was almost to 3 for the HVAC, but a solid 65% of the core load, and the 2nd highest demand item behind the car charger. The problem is planning for demand. By average I could have a single 5K unit taking care of all my needs, and based on this a single 12K unit should handle everything, except a bunch of high demand items could all turn on at the same time and screw the pooch. On the inverter side It's usually about covering peak demand, on the battery/storage side it's about covering average load.

 

[niktak11]

Building a solar setup that could produce 400a at 240vAC would be quite the undertaking. 96,000 watts. I wonder if SolArk or EG4 has a 100K AIO for sale?

Sol-ark has a 60k but it's for 480V 3 phase

 

[yodamota]

I am not sure where 240v came into play here?

 

[ksmithaz1]

I am not sure where 240v came into play here?

Curious what you would consider bringing into play to run a house and a large garage/workshop. 208/3-phase? The problem is, most commonly available high draw electrical devices are 240v: hwh, hvac, dryer, range, ... Devices that will run at 120/240 (pool pump, well pump, power supplies ...) are generally more efficient at 240v as well. I have a small rack of computer gear here, which is all 240v capable, it's on my agenda to move it to a 240v circuit.

 

[ksmithaz1]

Sol-ark has a 60k but it's for 480V 3 phase

The EG4 / 1812 manual says you can stack up to 10 to get to 120KW. That would be 500A/240V, s 8 would get you to 400A. You'd probably have to carpet a square mile of property with solar panels and find a place to put in 8-16 racks of batteries, but you could do it. Generally the battery is about time, but if you are actually going to get a 400A demand, your going to need significant engineering, as you may need to draw around 2000A/50v from your batteries at any given point. I'd probably pair/quad independent battery sets bused to inverter's in pairs. It would be fun to build out. The problem with the EG4's is if you lose an inverter the whole system shuts down. Anybody have any experience with parallel Sol-Ark or other brands that don't fall over if you shut one off?

 

[Hedges]

The EG4 / 1812 manual says you can stack up to 10 to get to 120KW. That would be 500A/240V, s 8 would get you to 400A. You'd probably have to carpet a square mile of property with solar panels and find a place to put in 8-16 racks of batteries, but you could do it. Generally the battery is about time, but if you are actually going to get a 400A demand, your going to need significant engineering, as you may need to draw around 2000A/50v from your batteries at any given point.

At higher wattage, you might want high voltage battery (400V or 1000V). Most I've seen listed are 3-phase, 230/400Y or 277/480Y.
SMA sells one in Europe that is 75kW. In the US I only see multi-MW models from them.

The problem with the EG4's is if you lose an inverter the whole system shuts down. Anybody have any experience with parallel Sol-Ark or other brands that don't fall over if you shut one off?

Sunny Island is 120V, 6kW and can be connected all in parallel, or parallel/series for 120/240V split-phase.
It will continue operating with some disconnected.

Three can be connected for 120/208Y 3-phase (18kW), and optional whether it shuts off for lost phase or continues operating.
Four of those can be connected as "multi-cluster" for 72kW.


If OP can get by with about 100A 240V steady-state, surge to 200A for a couple seconds, then stacked inverters with 48V battery should work.
But as noted by others, it is more likely to have steady state loads of a couple kW, or whatever A/C draws.
What gets tough is providing enough battery for 24/7 A/C. If A/C is only needed when there is direct sunshine, easy enough to power with PV panels. Small battery for other loads at night. That's what I have.

 

[ksmithaz1]

What gets tough is providing enough battery for 24/7 A/C. If A/C is only needed when there is direct sunshine, easy enough to power with PV panels. Small battery for other loads at night. That's what I have.

I'm Jealous. The low is going to be 90 again this evening. The hotter the nighttime low, significantly impacts my time on grid. I need more battery.