One year off-grid in Alaska, a status update.

aksala

I just thought I'd post a 1 year follow up on my system here in Willow Alaska - 61.77478N. 

The system is a Conext XW6848+, MPPT 80 600 with a Conext Gateway, SCP and 22 Rec-N-Peak 320W panels and 3 AES Discover 42-48-6650 batteries. Panels are on the roof at 45 degrees facing 180 mounted using Ironridge feet and rails.

So far I've been very happy with the system as a whole. The Conext gear and the AES battery combination couldn't be easier, and of course zero maintenance on the batteries. My initial load calculations were fairly accurate as I was targeting for a 15KW/day load and so far the annualized load is between 13-14KW/day. 

Power production and utilization in the attached photo. A 7.5KW mobile light plant serves as primary generator for the winter. It's a 3 cyl Kubota diesel and seems to do well on fuel. I haven't gotten too far into the weeds on fuel consumption but it generally ran 7 to 8 days on 10 gallons, running 2 to 2.5 hours per day on average. My absolute longest time running the generator was 3 hours if we happened to have use more power than normal on a given day. 

This winter I hope to have the AGS module plumbed into the generator to make my life a bit easier. And have the generator in a shed, so that I'm not heating up the oil pan with a weed torch on days when it's 30 below. 

I found that the system can produce enough solar power as early as late January to avoid the generator given enough sun, but usually we're getting snow off and on so frequently along with the associated cloud cover it's hardly worth the effort to try to clear panels vs's just a few $ on fuel. 

The house is just under 1800sqft. The solar system is housed in the garage which is heated with a Toyo oil burner and set at 50F. The house is heated with a nice big wood stove utilizing a Toyo for the shoulder season. We burned just under 6 cords of spruce and birch. Hot water is via a Toyo semi-on-demand oil burner which works great for our needs. The well pump is a Grundfos slow start down about 54 feet and pulls about 940 watts. All lighting is LED of course. I have a large 28cuft refrigerator/freezer with ice maker as well as 3 large chest freezers plugged in. I am still using a very energy inefficient plasma flat screen TV, one of my largest energy hogs. But it works and has a beautiful display and the fuel to run it in the winter doesn't really add up enough for me to replace it yet. 

I'm happy to entertain any questions. 

BB.

Looks like a gorgeous home and beautiful area!

And thank you for the update. Always nice to hear both the good and the bad.

-Bill

Wheelman55

Very nice!  Would you please snap a picture of how you connected up the three AES batteries?  I’m assuming that you used bus bars.  I’m currently running one AES battery and might be adding another one or two this fall/winter. Thanks!

aksala

Wheelman55 said:

Very nice!  Would you please snap a picture of how you connected up the three AES batteries?  I’m assuming that you used bus bars.  I’m currently running one AES battery and might be adding another one or two this fall/winter. Thanks!

Here's a photo shortly after installation. I did not use bus bars. I did use cables I had custom made locally here in Anchorage. Lookup polarwire.com. 

Wheelman55

Thanks...I do use polarwire and make my own crimps.  Very good wire!

Who’s battery post covers are you using?  I put the heavy duty “slip over the wire” ones from polarwire on the 4/0 cable...they are a tight fit!

aksala

Those covers were on the batteries when I got them! 

ELYNN4

Thanks for your post - very informative!  I’m just finishing my second year off the grid in Talkeetna, Alaska - close by neighbors.  We have a 4500 watt fixed array with a Classic 150:and a Schneider 6048+ inverter.  We have two strings of Trojan L16 2V (Old school) FLA batteries with Hydrocaps.  We use a Northernlights 9 kw .  We run the generator about 200 hours per year, November, December and January.  October and February occasionally require the generator if it is cloudy.  We only discharge the battery bank 20%.  The house is +/- 2000 sq. ft., but only 850 is living space the rest is a garage/workshop.  Our energy budget is between 6 and 7 kw per day.  With the Hydrocaps the batteries require water every 6 months.  We hope to upgrade the batteries to the latest and greatest when the current batteries are at the end of their life - hopefully another 8 years from now.  

The generator and batteries are located in a Connex behind the solar panels.  The waste heat from the generator is plumbed over to the garage where a unit heater serves as the radiator.  The generator run time is 8 hours, 2 hours bulk and 6 hours absorb - it runs every fourth day in the dead of winter.

We heat the living space with wood - two cords per year.  We also have a Toyo OM 128 for hydronic heat and domestic hot water.  We too have the Grundfos slow start constant pressure pump for the well - great set up for off grid!

Ralph Day

Watch those Hydrocaps.  They only last so long.  Mine were gone after 3 years I think.  One, then another, then a bunch...then all of them.  The catalyst only has so many amp hours of charging recombination in them.  You'll notice by the absence of heat when you touch them...and/or increased water consumption.  Just touch a few every month to check.

softdown

Made sense to use your roof for mounting panels. But I'm going to argue for something else. Because why not?

You get more sun than you can use for several summer months at  ~ 62 degrees latitude. So maximizing summer harvest is hardly required. I'd argue for an ~ 60 degree panel mount for a few good reasons.

Not trying to be confrontational. Just wanted present and future Alaskan readers to consider alternatives.

ELYNN4

I have been concerned from day 1 about the Hydrocaps- from the very beginning some (6 out of 144) got warm and the rest didn’t.  I sent some caps back For testing and Hydrocap claimed that they were fine.  My question to them was “if they don’t get warm what other parameter is there to determine whether they are working?”  They couldn’t provide an alternative.  They sent me a dozen caps to try - some had their old catalyst and some had a new catalyst.  I still could not get them to perform as advertised.  That being said I still only need to add water twice a year.  I believe that because I don’t discharge the batteries below 80% and my charge rate is relatively low (90 amps max for a 2200AH battery bank).  I do have a fairly long, 6 hour, absorb time and I have the absorb voltage cranked up to 59.6 which ends up being 60.1 after temperature compensation.  So far so good...

BB.

The caps getting warm is a function of how much hydrogen and oxygen is flowing to the catalyst.

If some of your cells are not "bubbling" (battery needs EQ, or other per cell issues)--Then those caps will not get warm.

-Bill

ELYNN4

The cells bubble towards the end of the absorb phase - off gassing to the point I added a vent fan to the battery box.  SG is 1.28-9 on all cells.

softdown

ELYNN4 said:

I have been concerned from day 1 about the Hydrocaps- from the very beginning some (6 out of 144) got warm and the rest didn’t.  I sent some caps back For testing and Hydrocap claimed that they were fine.  My question to them was “if they don’t get warm what other parameter is there to determine whether they are working?”  They couldn’t provide an alternative.  They sent me a dozen caps to try - some had their old catalyst and some had a new catalyst.  I still could not get them to perform as advertised.  That being said I still only need to add water twice a year.  I believe that because I don’t discharge the batteries below 80% and my charge rate is relatively low (90 amps max for a 2200AH battery bank).  I do have a fairly long, 6 hour, absorb time and I have the absorb voltage cranked up to 59.6 which ends up being 60.1 after temperature compensation.  So far so good...

A six hour absorb period at 59.6V! Shiver me timbers! Good thing your Hydrocaps work.

aksala

softdown said:

Made sense to use your roof for mounting panels. But I'm going to argue for something else. Because why not?

You get more sun than you can use for several summer months at  ~ 62 degrees latitude. So maximizing summer harvest is hardly required. I'd argue for an ~ 60 degree panel mount for a few good reasons.

Not trying to be confrontational. Just wanted present and future Alaskan readers to consider alternatives.

 The math is the math and I won't argue. But panel mounts are rather site specific don't you think? So while 60 degrees makes sense on paper, the sun is actually so low and so short in Nov - Dec that the benefit of the angle is lost unless you have a site that gives your panels a clear shot to the southern horizon. I only have one year of my particular site data but given the typical weather, Oct - Jan are usually either so cloudy or the sun so low or the panels covered in snow every day that generator use during those months is simply a given, unless your battery bank and your daily usage accounts for the loss of production. Some sites can get a clear shot to the horizon here, either by elevation or facing a swamp or other cleared site with no trees. But I'm in the flats and in the woods where my tree height averages about 60 to 80 feet. When the sun is only popping up between 3 and 6 degrees for a couple of hours a day, the angle isn't going to buy you much. 

 I could also argue that array placement is also dependent on your battery plant and proposed usage. If I had too steep an angle on a ground mount for instance, I might not be getting the power I do in the early morning or late afternoon for instance. As the sun comes up and starts making power in the summer at 7am, it's over an azimuth of about 60'. If the day has been particularly cloudy and rainy, I may not catch up on the batteries until early evening, as the sun is still up but over at about 270 or beyond while the array is oriented at 180. Some may argue for a tracker here, but I found it easier and less expensive to simply over panel a bit and it seems to work out. 

aksala

@ELYNN4, good to see a neighbor here. Also, a very nice place you have up there! 

It's interesting to see the similarities and differences, especially in your battery bank. I was originally looking at a similar bank but when @Dave Angelini brought up the AES batteries I decided to go that route. However if we had been doing this a year earlier I think I'd still have the large FLA bank. While my capacity is less I didn't need the space to store the batteries and deal with the maintenance and that was a plus for me. I knew I'd have to rely on generator power in the winter and the rapid recharge is great. 

What is interesting to me is your generator use is roughly the same yet your wood use is considerably less. Likely the hydronic heating. I wanted to go that route as well but I ended up having to cut that from the build due to the budget. Luckily there's plenty of wood around.  

I like the ground mounting you did. Is that on the side of a conex?

ELYNN4

Thanks aksala. Yes I am using a connex for my generator shed.  I wrapped the connex on the exterior using 2x6 studs, insulated and sided it (lip stick on a pig).  That meant I could use the entire 8’x20 interior to house my battery bank, inverter etc. as well as two generators (Northernlights 6&9 KW - the 6 is my backup).  The panels are leaned up against the connex about 18” off the ground.  This allows me to rake off the panels whenever it snows.  I’m able to plow the snow past the drop zone of the panels, which minimizes the manual labor 😏

The batteries are approaching 3 years old.  The first year was house construction.  We’ve been living full time in the house for two years now.  I do a fair amount of MIG welding and the system is performing beyond expectations.

I look forward to upgrading the battery bank.  It’s hard to imagine where the storage technology will be when it’s time!

ELYNN4

Here’s a picture of the connex - you can see how it supports the solar panels.