First Year of Our Conext SW Grid Interactive System

MrM1

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.

mcgivor

Good to hear things are going well, one word of caution don't turn the refrigerator off, even 4 hours can cause the temperature to rise enough to spoil product, I attempted the same only to discover the temperature went from 4 to 8°C, in the refrigerator section. The refrigerator in my case is not an enormous consumer, but when added to the CSW's 40W self consumption it adds up overnight. To reduce the tare load, I programed the CSW to turn off overnight when loads are minimal, it's output is fed into an auto transfer switch, a second smaller inverter  with 12W tare, is fed into the alternate source side, which carries loads until the CSW resume it's role in the morning this works well in my application. Could use an even smaller inverter say around 300W, current one is 2000W, what I had on hand,  to further reduce tare losses, the inverter based refrigerator is key to using such a small inverter.

MrM1

Thanks for the heads up. I do plan on getting a small 3000w Harbor Freight inverter generator too to run the smallest of window AC units, about 5000 btu.   I could also use it to charge the batteries, but not sure how badly the CSWs charger would be limited on 1 leg and only 30 amps ac input. It will work  but it will limit charge current  

Graham Parkinson

Mcgivor - Good idea on the auto-transfer switch - where did you get such a beast and how much do auto-transfer switches cost?  Any description of it?  Haven't seen such a thing for sale around here. 

We have an LG inverter fridge which indeed has a small starting load, but still the fridge is the majority of our loads.  The fridge has all of it's works at the bottom rear (compressor and coil) with a cooling air inlet and cooling air outlet.  It occurs to me that I can duct these separately to the exterior wall (one high, one low for added chimney effect) and reap benefits of improved efficiencies due to lower exterior temps.  The other nice thing about not having any cooling coils under the fridge's exterior skin (surfaces don't get warm) is that I can add exterior foam board insulation too.

mcgivor

Graham Parkinson said:

Mcgivor - Good idea on the auto-transfer switch - where did you get such a beast and how much do auto-transfer switches cost?  Any description of it?  Haven't seen such a thing for sale around here. 

We have an LG inverter fridge which indeed has a small starting load, but still the fridge is the majority of our loads.  The fridge has all of it's works at the bottom rear (compressor and coil) with a cooling air inlet and cooling air outlet.  It occurs to me that I can duct these separately to the exterior wall (one high, one low for added chimney effect) and reap benefits of improved efficiencies due to lower exterior temps.  The other nice thing about not having any cooling coils under the fridge's exterior skin (surfaces don't get warm) is that I can add exterior foam board insulation too.

The auto transfer switch I ordered directly from the manufacturer Feeo, cost $20 as part of a larger order, it's quality is very good for the price http://m.feeo-solar.com/atuomatic-transfer-switch/2p-automatic-transfer-switch-ats.html
Note I'm not restricted by certificate requirements such as UL, if that is of concern, check compliance.

My Panasonic refrigerator uses skin cooling, during hot periods a small fan to move the air helps reduce the cycle count and one way to use excess production during the day.