Solar beginner

[Gdiego]

Hi everyone,

So I have 5 380W solar panels and nothing else. I don’t know much about solar systems yet, but I want to install these on my roof to reduce my power bill. Im not sure what type of inverter, batteries, charge controllers etc to be looking for. The reason I have 5 is that they were given to me, so I’d buy another 1 or more if necessary. I am confused about whether to have them in parallel or series and what inverter would support each type.

 

[12VoltInstalls]

confused about whether to have them in parallel or series

You need one more panel to use them 3S2P: three series, two parallel; or 2S3P. Three in series is almost 130V- many smaller charge controllers can’t do that. Two in series is only ~85V open circuit. So you can see either way you need a number of panels that isn’t a prime number.

6 of those panels could produce 72A+ for the charge controller. You’ll need one that can handle that. Epever has some that will handle them as do US MPP Solar, victron, etc.

FWIW 6 of those panels will probably only make 3-12KWh per day. Depending on sun.

 

[Rednecktek]

roof to reduce my power bill.

So are you thinking a grid-tie system to get money back from the power company or off-loading some of your stuff to run on the solar instead of the power company? These are 2 drastically different design processes and need to be planned accordingly.

Also, definitely get a 6th panel, prime numbers are a pain to work with.

Welcome to the forums!

 

[Gdiego]

So are you thinking a grid-tie system to get money back from the power company or off-loading some of your stuff to run on the solar instead of the power company? These are 2 drastically different design processes and need to be planned accordingly.

Also, definitely get a 6th panel, prime numbers are a pain to work with.

Welcome to the forums!

Thanks for the reply, I had no idea about that first option! I was thinking of using the solar power to run some of our stuff at home. Thanks, this helps me have a sense of direction on what to research

 

[Gdiego]

View attachment 88739

You need one more panel to use them 3S2P: three series, two parallel; or 2S3P. Three in series is almost 130V- many smaller charge controllers can’t do that. Two in series is only ~85V open circuit. So you can see either way you need a number of panels that isn’t a prime number.

6 of those panels could produce 72A+ for the charge controller. You’ll need one that can handle that. Epever has some that will handle them as do US MPP Solar, victron, etc.

FWIW 6 of those panels will probably only make 3-12KWh per day. Depending on sun.

Thanks for the illustration, I will definitely get at least 1 more panel. It seems like I’ll head towards having a 2S3P or even 2S4P setup. Thanks for the charger recommendations, i will need to see how much space I have exactly and decide how many panels, so that i can find an appropriate charge controller and inverter. What else is important in regards to batteries?

 

[Rednecktek]

Thanks for the illustration, I will definitely get at least 1 more panel. It seems like I’ll head towards having a 2S3P or even 2S4P setup. Thanks for the charger recommendations, i will need to see how much space I have exactly and decide how many panels, so that i can find an appropriate charge controller and inverter. What else is important in regards to batteries?

The higher voltage you can supply to your MPPT controller, the more effective it is in generating power under lower light conditions. Assuming you're not risking over-volting, a 3s2p will probably produce more actual wattage in a given day than a 2p3s setup. Same number of panels but the controller has more to work with. A big advantage of having multiple strings in parallel is you can face arrays for more even sunlight time, so a string SE for morning sun and a string SW for afternoon sun. Longer time with better sun angle on at least 1 string adds up.

Now, having said all that, let me throw my standard blurb in here to go over.

 

[Rednecktek]

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.

 

[wattmatters]

Could hook them up with micro inverters, one per panel for an AC coupled system.