Hi folks!

Tomcs2013

Just joined, and just starting the sometimes cryptic world of AC/DC Solar Grid and off Grid use.
I currently have:
2, 250 watt Grape Solar panels mounted on my metal deck roof
1, Outback FM80 Charge Controller
1 bank of 12v deep cycle, in series to make 24v
1 bank of 6v golf cart batteries in a series to make 24v
Waiting for arrival of Midnite-MNDC250 Midnite Solar MNDC250 > 250 AMP Mini DC Disconnect AND Midnite-MNDC-GFP80 MidNite Solar MNDC-GFP80 > 80 AMP 150 VDC PNL Ground Fault Protect Breaker.
1 inverter SunGold 6000W Peak 12000W Split Phase 120V 240V Pure Sine Wave Inverter Charger 75A 24V ( yeah I know it's Chinese) but was new in the box for a very good price I happen to come across locally.
Various fuses power disconnects and such.

The panels are on the roof (earth grounded) running into a combiner box through a 100a fuse into the Outback Controller, then connected to the 12v now 24v battery bank.

NOTHING ELSE HAS BEEN INSTALLED

Just had a back operation last week so I'm going to use this downtime to try and figure out how to install the rest of the system the safest way.

My goal is to expand to at least 12 panels @ 250 watts ea. I want to use Solar power daily through the grid and still maintain batteries for power outages (they happen frequently)

I do have a generator @ 3000 watts running through a transfer switch with 10 breakers.

I have a well pump 5hp that requires 220v, and AC needing 220v as well.

That has lead me to here. I'm almost a fresh clean pallet open to suggestions and opinions.

Thank you :-)

waynefromnscanada

Re: Hi folks!

Hi Tomcs, welcome to the forum.
Read over your list and the first thing that hit me was a monster 6000 watt, 120/240 PS inverter and only 500 watts PV.
What the heck are you proposing to power?
OH! Since I posted the above, I read the rest of your thread. lol
A 5 HP Pump! Man you're looking at a monster system!

Cariboocoot

Re: Hi folks!

Welcome to the forum.

Where to begin? How about "reverse"?

What you are planning is basically an off-grid system which can make use of the grid when it is available? Or is it a battery-based grid tie system that will provide back-up power when the grid goes down? It makes a big difference, specifically in the inverter you choose. One thing I would not choose is an inverter that claims it can produce 6kW from 24 Volts. For one thing "75A @ 24V" is only 1800 Watts. At 6kW it would pull more like 250 Amps, which is a lot of current. Never mind what happens at a surge of 12kW.

Right now you've got 500 Watts of panel, and a whole lot of battery. That's not going to work very well for either scenario. It would barely keep the golf cart batteries up. You're looking at about 16 Amps peak current @ 24 Volts. A 100 Amp fuse on those two panels is not at all necessary, nor would it provide any over-current protection as the two panels will produce only about 8 Amps each.

And speaking of which, they should be in series to charge a 24 Volt system. I'm pretty sure the Vmp on those is around 30, which is not enough to do the job. In series you get 60-ish, which (through the FM80) would work for your 24 Volt system.

I'd say now is the time to think about going to a 48 Volt system, given the 240 VAC loads you want to run. This would mean configuring your total twelve 250 Watt panels as four parallel strings of three in series (Vmp 90, Imp 24 for the array). This 3kW array would supply about 48 Amps @ 48 Volts and would work well with two parallel strings of GC2's (440 Amp hours @ 48 Volts). You should be able to count on approximately 4.8 kW hours per day from this battery bank and about 6kW hours from the array.

You'd need to change a few things, not the least of which would be the inverter.

Tomcs2013

Re: Hi folks!

Oops, fat fingers it's a .5 hp pump.
I have to get more panels for sure. I wanted to install two before my operation, looking to buy at least 6 more in Dec.
The well pump would be nice to run during a power outage the 3000 watt generator does it fine while using other not so greedy circuits through the transfer switch.

Tomcs2013

Re: Hi folks!

I'm learning so forgive me for misused terms. :-) Battery based grid tie would be my goal. Like I stated the inverter was a good price, and realizing Chinese junk is not the best I figured the output would not be 6000 watts, was hoping to achieve at least 3000 though. It's a starting point for a couple hundred bucks. I though that through this exercise of building a system I would hopefully learn quite a bit.

If I were to pay someone for a system I would learn very little. Although I know I need to get a qualified electrician to make connections to the grid. I may run this through a sub panel at first powering a couple circuits.

You stated
"Right now you've got 500 Watts of panel, and a whole lot of battery. That's not going to work very well for either scenario. It would barely keep the golf cart batteries up. You're looking at about 16 Amps peak current @ 24 Volts. A 100 Amp fuse on those two panels is not at all necessary, nor would it provide any over-current protection as the two panels will produce only about 8 Amps each.

And speaking of which, they should be in series to charge a 24 Volt system. I'm pretty sure the Vmp on those is around 30, which is not enough to do the job. In series you get 60-ish, which (through the FM80) would work for your 24 Volt system."

I agree on both of these points, more panels very soon (probably 6), and While I'm at it I will connect in a series (thank you for that)

The 48 volt sounds interesting, I certainly can build with that in mind, but right now limited to the current inverter. I does not appear to be to difficult down the road to change to 48 volts (in my head anyway) Thank you for the information, it's all greatly appreciated. If/when I could see my way to a 48 volt inverter what would the recommendation?

Cariboocoot

Re: Hi folks!

If the inverter you have is not a grid-tie inverter it isn't going to work for grid-tie. So that could be a problem. It may be able to utilize grid power for charging (and transfer loads to it) but it will not be able to sell surplus power back to the utility (for which you need approval of the utility).

There are a few of these 'hybrid' inverters available, most notably the Xantrex (now Conext) XW and the Outback Radian. Neither is cheap, because they need to be complex to handle all the functions.

Expanding to a higher Voltage system can be made simpler by planning for it now. For example, an array of high enough Voltage to charge a 48 Volt system through an MPPT controller can also do a 24 Volt system. And wiring capable of handling the current for a 24 Volt system will easily handle the lower current (for same power) of a 48 Volt system. Plan both first, and see what coincides between the two. The batteries would need re-arranging at least and the inverter replacing, and some of the circuit protection/disconnects would need careful thinking so that they could handle either system and you only have to buy them once.

Education can be a very expensive thing. Especially at the college of hard knocks.

waynefromnscanada

Re: Hi folks!

Cariboocoot wrote: »

Expanding to a higher Voltage system can be made simpler by planning for it now.

Education can be a very expensive thing. Especially at the college of hard knocks.

So true.
I too started out small, never ever even guessing that one day I'd be running everything off grid. But as time went by and I became ever more addicted, my system grew. Today I find myself painted into the 12 volt corner and the only way out is to win the lottery.
If I had known back then what I know now, I most definitely would have gone 24 volts. I'm getting by on 12, but pushing the system to the max on a regular basses and cannot expand it any further.
That said, for me, if I hadn't started out as I did, I'd probably never have gotten into solar because of the initial cost.
Hummmmm, if only the panels had been as cheap back then as they are now.