Newbie building a portable generator

[murdsman]

I have some land that is currently off grid. We are planning on building next summer, probably starting with a garage. I am wanting to build a portable solar generator to power some small power tools and recharge tool batteries. I'm thinking about 2000 W inverter, 400 - 800W solar array, appropriate sized solar controller and a couple 100 ah lithium batteries to run 12 or 24 volts. I am not locked in on any of these specs but trying to keep it a manageable size and reasonable cost. I am new to this solar world and do not have a deep knowledge of electricity. I know a little more than the basics but am excited to learn and build something like this.
With this generator I would like to have the ability to charge it with a gas generator if solar charging is not sufficient for one reason or another.
Would that mean that I would need a inverter/charger? I think they have internal transfer switches, are there other components that I would need like a converter?
I would like to keep the size to a medium to large cargo box with wheels that I could move around where needed.
Any recommendations would be appreciated.

 

[murdsman]

What a beautiful build you have done. The detail is incredible.
Looks like you have a separate charger from the inverter. What are the advantages / disadvantages of that?
What is the purpose of the shunt?
As usual the more I see the more questions I have.
Thanks for the input.

 

[murdsman]

Thanks for the feed back. Another question I had was you have a positive and negative bus bars. In Will's 400W schematics I have only seen a negative bus bar. How does that work?
Also with inverters I see that there are low and high frequency inverters. I'm thinking that with my application being mostly outdoors that it is not worth the extra cost at this point. What are the advantages and disadvantages with each?

 

[dehv]

If you will be doing construction You want low frequency inverter to start hard loads like air Compressors and power tools.

Get a little inverter type generator to backup the solar, and make sure your solar is at least a cheap real mppt, ie a powmr/makeskyblue controller or better.

 

[williamsk913]

If you will be doing construction You want low frequency inverter to start hard loads like air Compressors and power tools.

Get a little inverter type generator to backup the solar, and make sure your solar is at least a cheap real mppt, ie a powmr/makeskyblue controller or better.

Depends. Low frequency inverters are super heavy. For a portable power station, not the best option.

 

[williamsk913]

I have some land that is currently off grid. We are planning on building next summer, probably starting with a garage. I am wanting to build a portable solar generator to power some small power tools and recharge tool batteries. I'm thinking about 2000 W inverter, 400 - 800W solar array, appropriate sized solar controller and a couple 100 ah lithium batteries to run 12 or 24 volts. I am not locked in on any of these specs but trying to keep it a manageable size and reasonable cost. I am new to this solar world and do not have a deep knowledge of electricity. I know a little more than the basics but am excited to learn and build something like this.
With this generator I would like to have the ability to charge it with a gas generator if solar charging is not sufficient for one reason or another.
Would that mean that I would need a inverter/charger? I think they have internal transfer switches, are there other components that I would need like a converter?
I would like to keep the size to a medium to large cargo box with wheels that I could move around where needed.
Any recommendations would be appreciated.

Don't know where you are at, but look at building a 280ah battery to put in it. I completed a very similar build. It is in a toolbox system and the inverter part is in a separate box that connects to the main one via high amp Anderson power pole connections.

 

[Countrybumpkin]

Don't know where you are at, but look at building a 280ah battery to put in it. I completed a very similar build. It is in a toolbox system and the inverter part is in a separate box that connects to the main one via high amp Anderson power pole connections.

Sounds like what I want to do. Do you have a schematic?

 

[williamsk913]

No schematic, but I am happy to answer questions?

 

[Rednecktek]

Before you decide anything or spend any money, get a better handle on your power needs. Things will change a LOT with seemingly small decisions. A couple of examples would be:

to power some small power tools

Miter saws, circular saws, etc will really REALLY want a Low Frequency inverter which are heavy and expensive

and recharge tool batteries.

A Pure Sine Wave high frequency will have no trouble at all

I'm thinking about 2000 W inverter

Will that be in LF or HF? Is that going to be enough to run all the things you might want + 30% for fudge and efficiency factors? Or are you going to have to throw it away because it can't hold down the load?

to run 12 or 24 volts.

That's going to be an important decision to make up front, inverters aren't multi-voltage so you need to decide early.

400 - 800W solar array

Where are you going to stick the panels? Since you're wanting portable do you have a plan to deploy, aim, and pack up these panels?

I could go on and on, but you see the point that there are a LOT of decisions to make. You're asking questions and noodling it down though which is a GREAT first step!

So, head over to the Resources section and grab the Power Audit form. Start by throwing in the numbers that you would REALLY want to have, factoring in power tools and margarita machines and hot tubs and so on.

Then start whittling that down to what your really NEED to have. Trying to undersize things to save money/power/etc will burn you if the system won't do what you need it to.

Then try fiddling around with your parts and see what a 24v system gets you over a 12v. How much can you generate with 400w vs 800w of panel. By poking at the numbers you can get a feel for how things can be adjusted.

The Power Audit form will tell you 3 very important things that will be base decisions of your system. 1: It'll tell you what size and voltage inverter to get for your needs, 2: it'll tell you how much battery bank you'll need to feed the loads, and 3: it'll tell you how much solar array you'll need to keep that system fed. The rule of thumb for battery banks is 3 days worth of battery before you need the sunlight again. You'll have to tweak with that a bit to find what you're comfortable with, but it's a ball-park number to get you started.

Then, once you've figured out all that it's time to go virtual shopping and start whittling down parts and budget. Run it all by us here and we can help you fine tune the system and figure out what you've missed in your plan, because we ALL miss something our first couple go-rounds.

Tl;Dr: You're on the right path, time to do some math!

 

[DaGoose13]