Purchased a home with 2 older (different) systems installed

midwesteddie · February 2023

Hi,

I'm fairly ignorant about all of this so bear with me as I find my bearings. We purchased a home at the beginning of 2019 with 2 different solar installations. One is an Enphase array mounted on the roof of a "solar shed" that I'm fairly certain connects almost directly to our meter. I'm not currently asking about that system.

The second system was installed in 2004 (I believe) and I'm really not certain if all the settings are optimal or if we could be doing more. The sale of the home to us ended up being fairly contentious (because the sellers had issues with the well water) so they basically sold us the home and then refused to tell us anything about the systems (after lots of pre-sale promises to us).

This system is a ground-mounted (hybrid?) system with 40 Nickel-Iron batteries, 24 Kyocera KD210GX-LPU panels, 2x Schneider Electric Conext XW 6048 Inverter/Charger, 2x Xantrex XW-MPPT60-150 Solar Charge Controller, Schneider Electric Conext XW+ System Control Panel, Schneider Electric Conext XW+ Automatic Generator Start, Schneider Electric Conext ComBox

Also, shortly after we moved in, I updated the firmware on one of the MPPT60s (to v01.08.00-0006), but I got scared after that because I realized I could wreck the whole system and had no idea how to fix it so the other MPPT60 is still at firmware v01.05.00-0006. I know there were some charging optimizations in that 1.08 version, but I'm still a little nervous about updating the other one.
I spent about 2 hours the other night going through the ComBox taking screenshots of every setting for every device. I have that information compiled into a Word/PDF document and will happily share if anyone would like to take a look. I'm also somewhat newly logged into InsightCloud so I have a bit of historic data (and current data) there too.

My fears are that we are not getting the maximum benefit from this system due to a sub-optimal configuration (inadvertent or otherwise).

Here are several photos of our setup.

I'm not sure I asked a specific question yet, other than general assistance to verify that things are setup correctly. I don't want to spam the discussion with useless info please tell me what more information I need to provide.

Thanks so much!

Ed

midwesteddie · February 2023

I don't know if this is too specific or what. Is there a better place to post this or did I just violate some etiquette or something? I'll delete this if it doesn't belong.

BB. · February 2023

Good evening ED,

No--You did fine. Nobody here is "employed" to make posts on the forum. We are writing answers spare time.

When a post is more complex... You are limiting the number of posters that can answer--And for others, it may take a day or so to read through your post and come up with relevant answers.

In your case--Your basic system was probably "state of the art" 20 years ago... But today some of the major components are no longer available today (and parts may be difficult or impossible to find).

Also you are asking questions about a very sophisticated set of hardware--I can give some "basic answers", but I (personally) am not qualified to give you detailed programming/configuration help.

Also, you have NiFe battery bank... A bit of a different animal. NiFe are known for their long battery life (with electrolyte change every 5-10 years). And also they are relatively inefficient (Lead Acid are around 80-90% efficient, Li Ion >98% efficient, and NiFe are something like 65% efficient--In rough numbers). Your array to loads will be "less efficient" than other types of battery bank.

Also, many of the questions you are asking--We cannot answer--Because we don't know the detailed configuration of you (two?) systems.

I can give you some quick math so you can see if your system is running near "optimum" or not... Some guesses:

24 * 210 Watt panels = 5,040 Watt array
Location: (near?) Urbana Illinois
http://www.solarelectricityhandbook.com/solar-irradiance.html

Urbana
Average Solar Insolation figures

Measured in kWh/m2/day onto a solar panel set at a 50° angle from vertical:
(For best year-round performance)

Jan	Feb	Mar	Apr	May	Jun
3.07	3.52	4.19	4.67	4.96	5.23
Jul	Aug	Sep	Oct	Nov	Dec
5.46	5.15	5.07	4.36	3.04	2.68

bly The typical Watt*Hours per day (for NiFe batteries would be:

5,040 Watt array * 0.43 efficient NiFe off grid system * 3.52 hours of sun per day (Feb) = 7,629 Watt*Hours per "average" Feb Day

Typically for an off grid system, you would use around 50% to 65% of daily "predicted harvest" (allows for bad/stormy weather/random heavy load days) or 3,814 (very rough) "planed" daily usage.

The "typical" real life maximum charging current (cool/clear day/near solar noon) and assuming the battery bank (plus only AC loads) consumes maximum current:

5,040 Watt array * 0.77 panel+controller eff * 1/58 volts (?) charging = 66.9 amps maximum "real system numbers"

On any "average day", you may see as little as 1/2 that charging current (how clear the air, humidity in air, dust/dirt on panels, temperature of array, array tilt, etc.)... So somewhere between 33 to 67 amps would be the "usual" maximum available charging current in the middle of the day.

For the basic electrical, you probably will need to take off electrical panel covers and make schematics (best you can). Things like array wiring, AWG and distance of wiring (array wiring, controller to battery bank wiring, etc.)...

Eventually you should probably look at voltages and current in your system (with an AC+DC Current Clamp Meter) to better understand the current/energy flow in the different parts of your system.

I am not very knowledge able of NiFe batteries... So looking up a chart of NiFe voltages vs state of charge vs current flow (both charging and discharging) would help too.

Random site on NiFe batteries--How they work, electrical curves, maintenance (just a quick find--I have not looked in detail at this site):

https://www.electrical4u.com/nickel-iron-batteries-or-edison-batteries/

1.6 volts per cell * 40 batteries in series (guess ) = ~64 volts charging
1.0 volts per cell * 40 batteries in series (guess) = ~40 volts near discharged

Monitoring the current into and out of the battery bank, along with the voltage can tell you a lot about how your system battery bank is operating.

Can you give us the name/model number/AH capacity of your bank?

You sort of have to be careful here... I guess your off grid system is sharing with the Grid--So you want to (in general) avoid charging your battery bank with the grid then discharging the bank at night... You put 1 kWH into the battery battery bank and draw out (65% battery eff * 85% inverter eff = ~55% over all efficiency) 550 Watt*Hours at night...

NiFe batteries self discharge around 20-30% per month--You don't want to pay your utility to keep the battery bank topped off.

With NiFe batteries--As long as you keep them topped off with Distilled water, they are pretty rugged (unlike other types battery chemistry if you discharge them to dead, or over charge them, the batteries could be toast)... You don't have that in the background ready to empty your wallet for a new battery bank (new users frequently "murder" their first battery bank or two).

Other things to watch out for--Generators can do things you don't want... From not starting and putting you into darkness, to starting/running when you don't need them too--And drain your fuel tank. As well as all the other things like leaking radiator hoses, oil leaks, fuel leaks, cranking until the battery bank is dead.

Perhaps turning off Auto-Start for now (coming into spring, good weather, no power outages) may be a good idea.

Do you have the system installer's contact information? Perhaps you can buy him lunch and get some basic system information about your installation... You may need somebody onsite to help (at least initially) to get the system looked at and understanding your basic tasks. This stuff takes study to understand and configure correctly (download the manuals, print/read them, etc.).

-Bill

midwesteddie · February 2023

Thanks for the comprehensive (as possible) response. Of course, I know nobody here is an "employee." I just happened across this group when I searched for some of my hardware and was happily surprised to see others here with the same equipment (in relatively recent posts).

BATTERIES: I top them off about twice a year. I suspect they use more liquid in the summer months when they are "cooking" quite a bit more. Brand: 40 Changhong 400 Ah, 1.2V Nickel-Iron batteries. I have often wondered what good the batteries do us. Are we wasting lots of production to keep them charged? I think this is where I worry that things could be optimized. If we wanted to, could we ditch the batteries in the future and keep the remaineder of the system running. Others have told me, since you already have them, keep them. But I still don't fully understand how they help us. I think on sunny days the batteries get topped off with the sun and do get somewhat discharged at night.

LOCATION: Essentially correct. I'm a couple miles north of Champaign (which is right next to Urbana).

GENERATOR: We have an older Generac (probably part of the original installation). It gets maintined twice a year and I verify that it runs once per week. So far, it has worked fine for us. I'm not sure that it has ever needed to run (for real) for us.

INSTALLER: Long gone. That was the first thing we tried. There is a sticker on some of the hardware, but they are no longer in business. The previous owners were very meticulous so I have no doubt that they used excellent installers and took great care of the system while they had it.

We actually considered upgrading the panels on the older system, but nobody locally wants to touch them due to the complexity of the system. That's fine. We are actually in the process of adding an additional ground mounted array to cover our usage.

I guess I didn't really appreciate that I wasn't really asking simple questions. I naively thought someone could look at my settings and say "Change this setting. That setting is fine.", etc.

I'm including some screenshots of data here, but it's more for your perusal than any specific question. Again, I really appreciate your response.

Thanks!

Image: https://us.v-cdn.net/6024911/uploads/editor/la/gpkpzzo6wyo3.png

Image: https://us.v-cdn.net/6024911/uploads/editor/xc/cug9bs1mq9io.png

Image: https://us.v-cdn.net/6024911/uploads/editor/oa/otwv05m3v14a.png

Image: https://us.v-cdn.net/6024911/uploads/editor/ca/6vyzldibgkbu.png

BB. · February 2023

I don't see anything "wrong" with your system (from the graphs, I think, I understand).

You are at the point of trying to figure out what you want... And how much time and money you want to put into the system.

The Enphase system... That, along with some sort of Net Metering with your utility, is usually the best cost/benefit (low installation and maintenance costs, best system efficiency).

The inverter+battery bank is another issue. Of course, the previous owner has already spent the money on hardware and labor. And the choice of NiFe batteries, while not very efficient, have a very long life--Batteries being one of the major costs for system maintenance (new battery bank every 5-7-15 years--Depending on brand/model/operation/maintenance).

Starting from the beginning, what is it you want from your solar system(s). Save money, short term and/or long term backup power. or what.

Normally, when designing an off grid power system--I like to ask how much energy per day (on average) you want per day. Your solar panels+batteries+inverters can supply around 7,500 Watts per day this time of year (Feb) on average... Or even more if this system is set up for Grid Tied mode (basically, the battery bank is fully charged) and the PV energy is simply fed out to the main panel to be shared by your home loads and the rest to the grid (when the sun is up)...

If we take the battery losses out of the equation (because you are not using the battery bank when the grid is up and running), you will harvest even more power... Very roughly:

5,040 Watt array * 0.77 Grid Tied mode efficiency * 3.52 hours of sun per day (Feb Average) = 13,660 Watt Hours = 13.66 kWH per day.

Of course, you could get the same harvest with just a GT Inverter (or Enphase micro inverters) and avoid the whole MPPT chargers+Hybrid Inverters+battery bank+complex load panel(s).

And if you have the genset--And are happy with its function/fuel supply/costs... Do you even need/want the complexity of your Off Grid (Hybrid) solar power system.

So what is 13.66 kWH per month worth to you... Say your power costs $0.20 per kWH:

13.66 kWH per day * 30 days per month * $0.20 per kWH = $81.86 per month in cost savings for February (pure guesses)

Whether these numbers are correct or not--They do give you a quick formula for you to figure out the value of the energy your system generates--And how much time and money you may want to spend on the system.

And as a backup system, figure out what you "need" to run during a power outage (i.e., Refrigerator, Lights, Water Pump, Computer, etc.)... and make sure that the Panels+battery bank+inverter can supply those needs during the outage.

Or--You just plan on using the genset and accept the cost of fuel per power outage to run your home and mothball or sell off the OG/Hbyrd power system...

-Bill

Dave Angelini · February 2023

I would just add that the XW 6048 inverter/ chargers are 2 generations out of support. That means the things that were done to make this system more relaible for grid-tie are not there. Combox was replaced with Insight 5 years back. Really hard to tell purple and blue colors in combox....an old problem.

It looks to me that the PVAC summary graph ( Last one) has 2.5kw and 5kw loads that seem wrong. Are they real? I ask because this is often caused by XW DC voltages that are not set right, an issue with master and slave 6048's, calibration, or ?

As Bill said, what do you need this for? Just the insurance cost for this can be expensive (you did tell insurance?) and the NIFE batteries are for a doomsday mentality and really the most inefficient battery out there.

midwesteddie · February 2023

Thanks to both of your for responding. I'm trying to keep it simple because my understanding is still limited. That PVAC Summary graph: here is a version with less data. The higher line is PV Total Power and the lower line is Load Power. I'm honestly not sure what that means because it seams that "Load Power" also tracks solar, but in my head, I think of load as usage (probably incorrectly). Also, I have red-green "colorblindness" so, yeah, those charts are not great for me.

I am able to connect the ComBox to InsightCloud and get some information, but is the $475 Insight Home even compatible with my XW series inverters? I thought the specs said it requires XW+ (and I don't think my are XW+). Additionally, Amazon reviews are not great (but not a big sample size) for the Insight Home device.

I suppose our desire for this system is mostly to reduce monthly expenses. We currently don't meet our demands so we are expanding (with a long-time, local company with a great reputation) on a completely separate system, but we do live out in the country so extended power outages are not impossible. The generator is already connected to the "essentials." We definitely do not fall into the "doomsday" or prepper crowd though.

Since I suffer from the opposite of the Dunning-Kruger effect

, I think a more helpful question for me is: if either of you bought this house and money was not unlimited (not zero, but other things are more financially pressing), what would you do with this system? Even if you would do things that I personally am not capable of, it might give me some insight into what, if anything, I should be doing (or thinking about) with this currently functioning system. Maybe it's to update some components to buy me some more time going forward (instead of waiting for something to break). Maybe it's something else. I'm very open-minded and would love to hear your thoughts.

As far as insurance goes, I have told our State Farm folks multiple times about our system and just called last week to ask if I needed to do anything about the new system, and they always tell me "it's covered." Now, that probably means nothing unless I get my hands on the policy and read through it, but our actual agent has literally been to our home and seen all of the solar panels, etc. so I feel like there is at least a decent argument for some promissory estoppel. (I'm only half-serious about that.) We DO need to up our coverage for "extensions" of the home. We have 5 outbuildings plus, soon, 3 different solar installations, and our coverage for those extensions is only $79k. I would like to bump that up substantially.

Thanks again for your input and the continued conversation!

Purchased a home with 2 older (different) systems installed

Comments

Urbana
Average Solar Insolation figures

Categories

Purchased a home with 2 older (different) systems installed

Comments

UrbanaAverage Solar Insolation figures

Categories

Urbana
Average Solar Insolation figures