Author Topic: Got my Little Starter 24v Off-Grid 2.5+Kw System About Where I want It  (Read 2114 times)

Matrix

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I know some people have written me about the system I set up.  I think it has its strengths and weaknesses. 

I started out in mid Sept 2017 knowing absolutely nothing about solar and battery storage.  I just knew I did not want grid tie,  because I wanted to be up during an extended outage (think hurricane season).  So there is hope for the uninitiated. 

I did a month of research before purchasing anything,  and I did not find all the threads on various forums discouraging an off grid set up if grid power is available until November ... and after the system was up and running.  Those discussion probably would not have discouraged me as I was building the system as a hobby and for energy independence and not "green" or to save the planet or to save power. 

If I could start all over again,  with what I have learned,  I would do it again.      But things I would do differently:

1. I would have gone 48v
- It would have saved me about $300-$400 on batteries because I could have gotten 8 GC 230 Ah batteries for less than my L16s
- I knew the math (duh) ... I just did not think of it because I was so fixed in my head for getting the biggest L16s I could find
- And I could not afford 8 of them
- Also smaller battery cables and probably more efficient and less overall heat
- And now I am considering a mini split AC for daytime use ... You see where this is going.

2. I would have research inverters a little more.  But for the money,  the SW is a good little unit  (looking forward to what MN rolls out for when I have to replace the battery bank and move up to 48v)

3. I would have bought ProSolar roof rack rather than "UniStrut" rack rails and hardward
- it proved cumbersome to find suitable end clamps for unistrut  (I ended up using ProSolar clamps with the Unistrut that worked OK)
- AND ... the Unistrut at 10' left me only about 1" on either end for end clamps ... almost too short with my 3 panel wide array
- And now I cannot add more panels unless I go underneath with another 2 rack rails.  No problem,  but ProSolar would have cost very little more and would come in 16' lengths so I could have added yet a 4th string.

4.  I would have built in some kind of code legal Rapid Shut down system. 
- This seems to be something that is not talked about much in the forums and videos
- I had no idea about it when I installed
- I am working on plans and ideas to go back and install a Rapid Shutdown system now.

5. I would have bought a 6 string combiner rather than a 3 string (and probably would have integrated rapid shutdown)

Not much more I would have changed. 

The system has been preforming very well.  The dump load is now tuned and timed to work well with available light, fully charged batteries and excess power.  And the REC Panels have proven to perform well in even partial sun and cloudy conditions.  On most days I am producing 1000 watts by 9am even before the sun gets over the shad tree and is fully on the array.  By 11am I am producing all the power the system is demanding up to the limits of the array.  I have seen days were I produced 12.6 kWhs for the day.  Here is a glimpse of May so far (the .2 day was testing, the system was off all but 1 hr and the 3.7 day was rain and clouds all day.)

« Last Edit: May 16, 2018, 02:52:40 PM by Matrix »
Grid-Assist Off-Grid
REC TwinPeak 2 285W 3S-3P 2565w-STC 1926w-NMOT Array / Classic 150 / Conext SW 4024 Inverter
Trojan L16H-AC 435Ah bank 4S  with 7' of 4/0 cable
24 volt system /  Need 3200Whs Daily
My System Install

Matrix

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My April power bill was the lowest in my records for the past 13.5 years.    I cut my usage over half from last April 2017.  This year in April I used 532 kWh's from the gird or about $48 in energy.  (there was grid connect, taxes and other fees).   Not bad for 2200  a sq ft house with two 3 ton central AC units (although in fairness the one unit hardly ever comes on bc we are not in that part of the house much anymore)
Grid-Assist Off-Grid
REC TwinPeak 2 285W 3S-3P 2565w-STC 1926w-NMOT Array / Classic 150 / Conext SW 4024 Inverter
Trojan L16H-AC 435Ah bank 4S  with 7' of 4/0 cable
24 volt system /  Need 3200Whs Daily
My System Install

Matrix

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  • Posts: 335
Re: Got my Little Starter 24v Off-Grid 2.5+Kw System About Where I want It
« Reply #17 on: October 23, 2018, 03:28:00 PM »
System has been up and running since Oct 15, 2017.   2.6kW Array,   Grid-Interactive Conext SW 4024 Inverter running not connected to the grid the first 9 months and connect grid interactively (CSW AC Support Mode) the past 3 months.  This is NOT a grid-tied system in any way and does NOT sell back to the PoCo.  The system was designed as a 4000 solar generator to do 2 things:

   1.  Provide power to home essentials such as lights, fans, fridge, well pump, washer, etc in the event of a power outage
   2.  Offset the monthly power bill enough to purchase new batteries every 3-5 years with the PoCo savings

So far in the past year (thru Oct 15, 2018) the system produced 2.25 Megawatts which equals about a $300 savings on our annual power bill.  I expect more in the 2nd year, the first 3 months I was generating only about 60% of my current monthly average.  The 4 Trojan L16 batteries that where purchased costs $1,275.   So my annual power bill savings are on track to pay for new batteries in 4.25 years.  Should be about right if I can keep from destroying the first set.  So far so good.

System over the past year has performed as well or better than expected.  Powers my entire home except for AC and Cloths dryer.   Will power all my needs for about 15 hours plus and would power much longer in a power outage if used moderation turning off the fridge for a few hours from midnite to 8am each day.  (fridge is the largest load at 2500 Wh's per day).

Thanks for all the help over the past year.
« Last Edit: October 23, 2018, 03:30:01 PM by Matrix »
Grid-Assist Off-Grid
REC TwinPeak 2 285W 3S-3P 2565w-STC 1926w-NMOT Array / Classic 150 / Conext SW 4024 Inverter
Trojan L16H-AC 435Ah bank 4S  with 7' of 4/0 cable
24 volt system /  Need 3200Whs Daily
My System Install

bee88man

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Re: Got my Little Starter 24v Off-Grid 2.5+Kw System About Where I want It
« Reply #18 on: October 24, 2018, 07:57:41 AM »
MegaWatt Hours, that's a bunch different than just MegaWatts instantaneous.

Last year I ran 1500 miles...Last year I ran 1500 MPH

Fridge @ 2500kWh per day needs refined also...that is about 5 months equivalent to your stated PoCo bill alone...