New Solar Questions

[sloth8871]

Hello, I have been recently researching and shopping for solar, as expected retail installers are quite expensive so that got me looking for alternatives. I started with SolarWholesale.com and have now branched into general DIY research and trying to educate my self on what it takes to gather the components myself to install and configure a grid tied system that would cover my daily needs with the configuration now, be available during grid down to act as a generator when the power is out, and to add batteries shortly down the line after I get the system operational for backup power and overnight power to get to fully self-sufficient power generation for my home.

I live in the Austin area and my average daily usages varies from 22 to 60kWh depending on the season. average monthly is 1100 and annual for our first year in this new home was 13200.

For this amount of usage I have calculated ~9Kw solar panel system would be needed but was going to go for 10 or 11 just to have overhead and a bit of room for future growth and battery charging capacity.

My first question is around solar panels. I have a couple of leads on used panels in my area, one is from a commercial project that has several First Solar Series 6 Panels for sale FS-6440's these being commercial panels I am curious if they are compatible with residential solar inverters, controllers etc. but I honestly don't know how to tell. Their specs differ quite a lot from a panel designed for grid-tied residential panels...
440 watts
VOC 219.6
ISC 2.55
VMMP 183.6
IMMP 2.37


The other panel that I have an opportunity to by are Aptos DNA-120-mf26-360w.
360 watts
VOC 40.6
ISC 11.24
VMMP 33.8
IMMP 10.66

the very different ratings for these panels makes me think that the first solar likely wont be compatible with a residential system but I really don't know. I guess this would come down to the inverter(s) input capability?

Follow up question would then be assuming either of these panels are compatible what else would I specifically need just a general major component checklist. I am not looking for a full solution just the directions really on where to go for resources to educate myself and begin understanding and documenting what components I need to assemble to make a working system.

I believe I need a hybrid inverter to accomplish my goal, possibly 2 to support a 10Kw+ array but I am confused about which to choose, micro or string, then there are controllers, MPPTs etc. I am not sure which is needed or best to get.

Any help appreciated. Thanks!

 

[sunshine_eggo]

For FS-6440, you'll need an MPPT with a 250V PV input limit.

For Aptos 360W, you'll have more flexibility. Many more options with MPPT 145-150V PV input limit, and you'll easily be able to put 3 panels in series (3S) and then parallel multiple 3S strings.

Can't comment on the rest.

 

[chrisski]

For checklists, try the DIY blueprints linked up top of the webpage.

 

[foggysail]

GRID TIED!!!

I doubt you will like my post. Do you have an electrician background, familiar with codes, does your town/city allow you to install a solar system without proper licenses, does your electrical provider allow homeowners to tie to their grid without local permits issued to licensed holders?

Sure, nothing wrong with doing all the research for general knowledge if you later deal with a solar company for installation. Otherwise-------

 

[x98myers7]

I personally will not attempt a grid-tied system as a DIY project. Just my opinion.

Have you considered that many power companies have tariffs and fees they charge for you to push power back into the grid? this effectively "steals" some of the energy you generate. In most cases, grid-tied systems are roof mounted arrays which requires rapid-shutdown modules to be installed which disable the solar array in the event of a grid outage. neither of those things make grid-tied worth it, IMO. not to mention the order of magnitude more difficult and expensive grid-tied equipment is. I'll pass.

 

[sunshine_eggo]

I personally will not attempt a grid-tied system as a DIY project. Just my opinion.

Have you considered that many power companies have tariffs and fees they charge for you to push power back into the grid? this effectively "steals" some of the energy you generate. In most cases, grid-tied systems are roof mounted arrays which requires rapid-shutdown modules to be installed which disable the solar array in the event of a grid outage. neither of those things make grid-tied worth it, IMO. not to mention the order of magnitude more difficult and expensive grid-tied equipment is. I'll pass.

This is exactly my experience. I planned to put enough PV to cover 70% of my annual usage, but due to the way the local utility penalizes PV, it would have only reduced my bill by 30%. Even DIY ~$10-12K for a 10kW system would have had a payback period beyond our planned stay in the house. The only way to gain more benefit would be to redesign with zero export and add batteries... costing well over the GT $10-12K.

 

[sloth8871]

For checklists, try the DIY blueprints linked up top of the webpage.

Thank you, I will look for these.

GRID TIED!!!

I doubt you will like my post. Do you have an electrician background, familiar with codes, does your town/city allow you to install a solar system without proper licenses, does your electrical provider allow homeowners to tie to their grid without local permits issued to licensed holders?

Sure, nothing wrong with doing all the research for general knowledge if you later deal with a solar company for installation. Otherwise-------

I don't mind any and all input.
I want, or almost need, to be grid tied because I want the project to be up to code and properly inspected / permitted etc. If the day ever comes that we have to move and sell this home I don't want any of this to become an issue. I also live in the city and in a HOA neighborhood so I can't really just go slap panels on my roof unfortunately. All that said though, Texas has solar homestead laws that prevent an HOA from blocking solar installs for any reason so long as the project is properly planned, approved, and installed.

This is exactly my experience. I planned to put enough PV to cover 70% of my annual usage, but due to the way the local utility penalizes PV, it would have only reduced my bill by 30%. Even DIY ~$10-12K for a 10kW system would have had a payback period beyond our planned stay in the house. The only way to gain more benefit would be to redesign with zero export and add batteries... costing well over the GT $10-12K.

Cost is exactly why I am going as DIY as possible on this and sourcing used panels and what not. We plan to live here for the foreseeable future but there's no guarantees we stay either, life happens. So want to keep the ROI as low as possible but also protect our selves from the ever increasing electricity prices and grid issues that Texas is having during the extreme weather both in the summer and winter months these days.

Texas does not have solar penalties your excess just gets sold back to the grid at wholesale rates which is basically nothing and not something I am factoring into this plan at all.

Since I am looking to be 100% covered, do I technically NEED to be grid tied? I started down that road because I read that if the grid goes down certain solar controllers and inverters would go offline until they receive enough power from the grid to turn back on, AC Bonded perhaps was the phrase?

If I can do a permitted system that is off grid and self sufficient while maintaining my connection to the grid that seems like it could be ideal.

 

[GLC]

Thank you, I will look for these.


I don't mind any and all input.
I want, or almost need, to be grid tied because I want the project to be up to code and properly inspected / permitted etc. If the day ever comes that we have to move and sell this home I don't want any of this to become an issue. I also live in the city and in a HOA neighborhood so I can't really just go slap panels on my roof unfortunately. All that said though, Texas has solar homestead laws that prevent an HOA from blocking solar installs for any reason so long as the project is properly planned, approved, and installed.


Cost is exactly why I am going as DIY as possible on this and sourcing used panels and what not. We plan to live here for the foreseeable future but there's no guarantees we stay either, life happens. So want to keep the ROI as low as possible but also protect our selves from the ever increasing electricity prices and grid issues that Texas is having during the extreme weather both in the summer and winter months these days.

Texas does not have solar penalties your excess just gets sold back to the grid at wholesale rates which is basically nothing and not something I am factoring into this plan at all.

Since I am looking to be 100% covered, do I technically NEED to be grid tied? I started down that road because I read that if the grid goes down certain solar controllers and inverters would go offline until they receive enough power from the grid to turn back on, AC Bonded perhaps was the phrase?

If I can do a permitted system that is off grid and self sufficient while maintaining my connection to the grid that seems like it could be ideal.

Personally, I would start off with talking to your elec company in Austin if it hints with grid tie. Education is good but depending on how you will be shutdown by either city or electrical provider will be the key. Sorry really don't have a lot of good things to say about the Austin area. Pretty crazy down there. I think it is pretty much like California now.

 

[sloth8871]

Ok so sanity check. After doing some more research today I think I am starting to formulate a plan. I don't actually need to be Grid-Tied just Grid-Connected. meaning using an inverter that has an AC IN along side my Solar IN to provide supplemental capacity if it's ever needed. I don't want to do net metering and I don't want my system putting charge into the Grid.

After researching more it seems a couple things are true:
1) The First Solar panels are very incompatible with most all residential MPPT's and Inverters. the high voltage exceeds all the inputs, except the EG4
2) I am going to need 2 MPPTs / Inverters because most have max solar input ratings of 5-8000 Watts and Im trying to push 10 or 11.

That said. I think a feasible setup would be:
30 DNA-120-mf26-360w panels in 3s10p which should out put 121.8V @ 112.4 amps
That would mean I think that I'd need a combiner box of some sort to go to
2 Growatt SPF800T DVM's

This would give me 120 and 240 in an out of the box sort of setup


The other path I think would be
24 FS-6440's in 2s12p
also to a combiner of some sort that I've yet to look into and then to
2 EG4 6550-48's because these support upt to 500VDC input from the panels which would be putting out 370v @ 29 amps

I think I can configure these in split phase mode to provide 120/240? How would that impact total output if at all?

Do these 2 options track?

 

[cs1234]

Hello fellow Austin Texan Area HOA resident.

I would suggest having a transfer switch, automatic or manual installed with a 30 or 50 amp generator style hookup on it. You could then power circuits of your choosing during outages or any other time you want while still having power from the city on your other circuits. You could hook real fuel powered generators into it if need be, a prebuilt solar generator, or your own custom built solar system. Use ballasted ground mounts of some sort for your panels, personally I like the thought of the bucket with rocks style of ground mounts.

If and when you leave, it was like it never was.

You are talking about building a pretty hefty system as your first built by yourself system, think small but useful to being with.

I was without power and water for over a week during icemageddon, so I feel ya on the desire to go big and do it yourself.. but play with some small stuff first and read more of the excellent information on here. Watch Will's videos, check out a guy named hobotech for some more reviews on various items like small solar generators.. get your feet wet.