How can I correctly feed a 60 amp Renogy Controller Charger with eight 12 v 175 watt solar panels?

TellGRBill

We have a 40 year old upright freezer that I put a refrigerator thermostat in 30 years ago. Now that we have solar power, we turn off the freezer/refrigerator at night.  it has great insulation and it works fine for us.  But we have many appliances and lights that, if we don't watch it will deplete the battery bank of group 31 bus/truck batteries.  Our setup has many things that run on 12 volts. 

NOTE:  I just want to put the 120 volt line coming out of the inverter on an external LVD variable switch.  

We only started using the solar seriously about a week ago and we're going through a battery management learning process. We have choices for electricity: power line from the road, solar and gas generator.

TellGRBill

I think I found the solution to my low voltage disconnect of the inverter output line:

BB.

Solid state relays can get hot... Make sure you have good heat sinking and ventilation to help keep it cool.

Regarding SSR's... They are known for counterfeit devices. Including many marked Fotek (don't know if "real" or counterfeit mfg.). The 100 Amp rated devices do not seem to be able to manage anywhere near the 100 Amp rated current--Maybe 10 amps(?) (if counterfeit?):'

https://www.eevblog.com/forum/reviews/warning-dont-buy-fotek-solid-state-relays/ (review from 2019)

The current reviews on Amazon are not very good for the Fotek 100amp SSR:

https://www.amazon.com/SSR-100DD-Solid-State-Relay-Module/dp/B07PFDJQLV

A quick check, did not find a data sheet for a Fotek 100 amp SSR

https://pdf1.alldatasheet.com/datasheet-pdf/view/1440638/FOTEK/SSR.html

And the data sheet says it needs a large heat sink and fan if over 10 Amps of current.

Another teardown of a counterfeit (vs real photos) from 2019:

https://protosupplies.com/inferior-counterfeit-fotek-ssr-25-solid-state-relays-on-the-market/

From 2014, UL counterfeit mark warning:

https://www.prnewswire.com/news-releases/ul-warns-of-solid-state-relay-with-counterfeit-ul-recognition-mark-release-13pn-52-242919311.html

Real Fotek Taiwan data sheet (no 100 amp unit listed?):

https://www.fotek.com.tw/en-gb/product-category/143

More specs:

https://www.fotek.com.tw/en-gb/product/809

Unfortunately, you have stepped into a "dark corner" of the electronics supply chain where it is very easy to get mugged.

I don't know where you picked up the photo of the SSR to use in your drawing--But, most likely, that is the photo of a counterfeit unit.

-Bill

TellGRBill

Thank you for your comments !

Where do you suggest I get a good 100amp 12v to 120v module to do this job?

NANOcontrol

You still have to contend with the idle current of the inverter. I would think that solution buys you almost nothing. The battery is still going to be run into the ground.

TellGRBill

I have a remote control switch for the inverter, so I think it can be shut off easily if the shutoff activates.

I sent a message to Fotek, asking if the product on Amazon is a fake or a real Fotek item.

I was referred to their United States Distributor who confirmed that the Amazon listing is a fake, low quality item that will fail.

The US distributor representative, who answered the phone, confirmed all that BB said in his comments above.

Thank you Bill

The distributor questioned me about the details of our solar system and made some recommendations for a better product to do what I want done.

Fotek US distributor:  Infinite Thermal solutions INC. phone: 847 341 8090

BB.

Some companies that usually sell good products retail (no particular order):

https://www.mcmaster.com/products/solid-state-relays/solid-state-screw-terminal-relays-7/

https://www.grainger.com/category/electrical/industrial-controls-automation-and-machine-safety/relays/solid-state-relays/general-purpose-solid-state-relays?tv_optin=true&searchQuery=solid+state+relay&searchBar=true&tier=Not+Applicable

https://www.digikey.com/

Don't focus on one solution (such as an DC to AC SSR)... If you can DC switch a remote on/off for the inverter directly, probably the best choice.

Otherwise--Just turn on a light/bell/alarm for a warning, and then you can manually switch the loads off/on as needed.

Adding complexity always creates more possibilities of failure.

-Bill

TellGRBill

Again, Thank you Bill

I'm not sure how to link the low voltage disconnect to an alarm or light but I'll look into it when I get the LVD device.

XIXIAN DC 6~80V Voltage Detection Charging Discharge Monitor Relay Switch Controller with CaseXIXIAN DC 6~80V Voltage Detection Charging Discharge Monitor Relay Switch Controller with Case

Bill B.

I contacted Fotek and was referred to a United States distributor of Fotek products.
email from Fotek:
webanswer@fotek.com.tw
Thank you for your email.
First of all, the maximum rated current for our SSR series are up to 75A
as well as this kind of our products are full of fakes on market,
especially on e-commerce platform.
Please choose your purchase carefully.
For more information and quotation, please contact your local
distributor as shown below.
  INFINITE THERMAL SOLUTIONS INC.
  12421 Lions Chase Lane Huntley, IL 60142 U.S.A
  TEL:+1-847-341-8090
  FAX:+1-224-569-6704
  E-mail:randylee@itsheaters.com

TellGRBill

I have a lot of questions, trying to have an efficient system.

I'm in the process of trying to monitor the demands on the inverter from our 120 volt system so we can more effectively managel it.

I bought a

KETOTEK Digital Ammeter Voltmeter AC 80V-300V 100A, 2in1 Multimeter Panel 110V/220V, Volt Amp Meter LED Display Voltage Amperage Detector Tester Gau

Can I put the CT around the 10/3 wire going from the inverter to our circuit breaker panel to accurately measure the amps being drawn from the inverter?

BB.

Yes... You place the CT (current transformer) around ONE Wire. And your loads need to be powered by just two wires (i.e., Black+White, or Red+White). For a 120 VAC system that is easy.

For 120/240 split phase systems, you have loads that can be 120 VAC (B+W, or R+W) or 240 VAC (B+R). In split phase 120/240 you have two current paths.

Also, be aware that it is usually easier to work in "Watts" when managing the AC and DC sides of your power systems... I.e., just Amps is not enough:

DC math (and "simple" AC math):
"Power" = Voltage * Current
Power = 12 VDC * 100 Amps = 1,200 Watts
"Power" = 120 VAC * 10 amps = 1,200 Watts (technically V*A or VA--Need a true Watt Meter to measure AC power)

AC math (note, this is one simplification--There are other issues too):
Power = Voltage * Current * Power Factor

Because "Watts" are a single value on both AC and DC sides (excluding the details of Power Factor for AC, conversion losses, etc.)--It is a bit less difficult to keep track of how your DC sides and AC sides are performing

Also, while it is handy to know the "instantaneous" current/voltage--It is also helpful to have meters (DC and AC) that log Wattage (instantaneous) and Watt*Hours (or kWH) over time...

It is like having both a speedometer and an odometer for your car...  And having Watt*Hours (or kWH) is like having both a flow meter (gallons per hour or a "rate") and the actual amount of fuel used (gallons per hour * hours of usage = Gallons used).

This is an example of a "multi-function" meter (just an FYI LInk--I have never used this meter). Please note that this Amazon Link should point to the meter I am talking about (V/A/Watts/PF/kWH/Hz/etc.) but there are 4 different meters under this link:

https://www.amazon.com/DROK-Frequency-Electric-Voltmeter-Multimeter/dp/B09R1VZLHT?th=1

Normally, you are going to be managing the "total energy" in Watt*Hours (or kWH) your system harvests in a day (like 3,000 Watt*Hours) and the amount of energy your loads consume in a day (i.e., 1,000 WH of AC energy and 2,000 WH of DC energy).

The "management" is that you end up with a full battery bank by middle of the day and (very roughly) your energy consumed equals the energy harvested (because of efficiencies, different loads and harvests each day, etc.... It will not be "equal").

Say you have a 600 AH @ 12 volt battery bank.

600 AH * 12 volt = 7,200 WH of total battery bank
7,200 WH * 1/2 = 3,600 WH of "planned storage" (using 50% of bank capacity max planned for longer battery life)
3,600 WH of "planned storage" * 1/2 days of stored/no sun energy = 1,800 WH per day (no sun) for 2 days

During summer, "anyone" can manage a well designed solar power system. Your well designed system is capable (on average) of harvesting 2x or more energy per day than your "nominal" usage. So, the battery bank will be full by noon.

Where the rubber meets the road is winter... When you have poor sun/cloudy/stormy days and (as an example) you use 1,800 WH but only harvest 800 WH during a cloudy winter day... You have now have:

800 WH harvested - 1,800 WH loads = -1,000 WH of "deficient charging"

In the above make believe system, you have 3,600 WH (to 50% discharge) of "planned" battery capacity to use...

3,600 WH of battery (50% storage capacity) / 1,000 WH per day deficit charging = 3.6 days until you need a genset or cut back on energy usage

Depending on your DC side (charge controller, battery monitor system used, etc.), this is what you are looking for--The balance between all loads and all charging sources with respect to the battery bank.

There are lots of options from Amazon (amazingly low prices for many of them) from simple to complex:

https://www.amazon.com/s?k=dc+battery+monitor

And there are the more "professional" type solar power system BMS (battery monitor systems) too:

https://www.solar-electric.com/search/?q=victron+battery+monitor (and other brands too)

To a degree--What you really want is a "summary" of the battery state (as in state of charge). Note that some folks program the Battery Bank 100% AH capacity and manage State of Charge between 100% and 50%, and others program 50% of battery capacity (i.e., manage between 100% and 0%)... It is just math and the results are the same--Just what make sense to you and your family.

When you have a "battery centric" point of view--It makes things a bit easier to understand and manage. You are not focused on Amps/Volts/DC side/AC side... Your end goal is the Battery State of Charge (in %, or AH state of charge).

You see your state of charge is "falling" over several days--Then you can look at your specific AC and DC numbers and figure out which loads to "manage" (or when to fire up the genset).

We have not really talked much here about how folks "manage" their systems--And what works or does not work for each user...

I am showing a both a detailed and high level point of view here... It is easy to get buried in data and graphs and lose the forest for the trees.

Does any of this help?

-Bill

TellGRBill

We have ten batteries on our system, each battery has capacity of at least 90AH I believe.

Also, remembering our discussion of battery placement 25' from controller and inverter, I can't detect any loss of voltage from the batteries to the inverter. Remember, I used three 3/4" diameter welding cables bundled in a  one and a half PVC water pipes, for both positive and negative cables to the 25' stretch. Our controllers, we bought a 60amp controller for both the bus and farm house, are in parallel together in the bus setup now. one for each array.  We are able to recover to 100% SOC after a couple of hours in the morning, being somewhat careful with electricity use after the sun goes down.

I can read all the stats for the system on my cell phone, so all I need is to be able to see our consumption of power in amps /watts.

If I understand you, I should put the CT around the positive input cable to the inverter, and the meter lead wires to the positive and negative DC connections on the inverter.  Then I would have battery volts, and amps flowing into the inverter, thus watts for the 120 volt part of our system.

BB.

Sounds good on the DC side wiring from batteries to load(s).

One quick warning when working with Current Transformers (CT's)... Do not pass current through cabling if you do not have a CT connected to its meter... A Current Transformer on a cable carrying current and not connected to a load (typically a precision sense resistor) can generate 100's of volts or more. Creating a shock hazard (and the high voltage could damage/ruin the CT device too).

NOTE, you have an AC V/I meter (voltage / current). Uses a Current Transformer to measure AC current in the wire that passes through the transformer.

But like all transformers, they are only "useful" (when measuring current) on AC lines.

CT's cannot be used on DC wiring as the CT will not "couple" with the current flow in the DC wiring.

To measure DC current, you need a DC Power Meter and using either a precision shunt, or a "Hall Effect" tranducer (a transistor that measures magnetic fields).

Example of a "shunt" based (precision power resistor) DC power meter:

https://www.amazon.com/6-5-100V-Display-Monitoring-Voltmeter-Multimeter/dp/B0CC5C5M64

Note that Current Shunts are normally installed in the Negative wiring (assuming negative grounded system)--Partially because the shunt and shunt "sense wires" are at "ground" or "zero volt" potential--No need for fuses to protect wiring.

For Hall Effect based power meters:

https://www.amazon.com/Battery-Voltmeter-Capacity-Electricity-Coulometer/dp/B0BGWY1ZDN?th=1


Note the following shows the Hall Effect Transducer in the Positive Wiring--I don't think it matters negative or positive wiring here (other than you may have to flip the wiring from right to left instead of left to right through the transducer to get the "right" current polarity.

Note that this Hall Effect meter is a Battery Monitor--It was just a quick DC power meter that I could find that had a Hall Effect Transducer. This is probably not the DC power meter you are looking for.

I believe this is he Ketotek AC I/V meter you are looking at (or already have). Note the CT (and meter power) come from AC lines (not DC). In the case of CT's, it does not matter if the CT is on the Hot or Neutral cable.

CT and other current sensing devices only measure current through that one cable--So you to install the current sense device in a location that carries the current you wish to measure:

https://www.amazon.com/KETOTEK-Digital-Ammeter-Voltmeter-Frequency/dp/B01EWW1RJ4?th=1

-Bill

TellGRBill

So therefore.... I plug into the outlet 120 volt receptacle of the inverter for the inverter, to get the meter power, and run the neutral AC wire from the inverter through the CT ?

This morning when I turned on the refrigerator, (before the sun shined on the solar panels) the DC voltage dropped from 12.6v to 12.3v and recovered to 12.5v in minutes after turning the refrigerator off again. (before the sun shined on the panels)

BB.

Yes, you run either the AC output Hot or Neutral through the CT (does not matter which). The CT will measure the current through that one wire.

Lead Acid batteries do sag a bit under loads.

-Bill

TellGRBill

I need to find a source for a user, operational manual for:  XIXIAN DC 6~80V Voltage Detection Charging Discharge Monitor Relay Switch Controller with Case

I bought one , it didn't come with instructions for its use, and am having trouble understanding how to operate it.

BB.

There is some information here (note there are two different models... One is "single mode" and the other has 4 different "flavors" of functions. The instructions apply to both (mostly).

https://www.aliexpress.us/item/2251832699887023.html?gatewayAdapt=glo2usa4itemAdapt

It looks like there is enough information to get started setting up/programming.

-Bill

Note: The "programming" information is visible after clicking on the above link, then pressing the VIEW MORE button (may also be "orange" colored) that is just above the "Specifications" part way down the page.


I have tried a couple different format scrapings of the page if you cannot access the above View More button.

See attached files below (note these where done with "Chrome" browser--I can try FireFox if you cannot read the files below:

BB.

Here is a manual that may apply? For a different unit (more i/o lines)--But programming looks to be similar as above.

https://www.chikuden-sys.com/img/Digital DC voltage detection time relayController User Manual - C.pdf

PDF File below (should be same as link above--Just won't randomly disappear--I hope).

-Bill

TellGRBill

Thank you Bill

I'll try the instructions tomorrow.

I also ordered an alarm to be activated at a set high and low voltage.

Bill B.

BB.

I have clarified my post above (instructions are not obvious to access). I also attached a couple different file formats (with some conversion problems) too.

-Bill

TellGRBill

Thanks Bill

NANOcontrol

I have that version and they say it can do up to a 10 second time delay. That is very important in voltage monitoring.  At highest setting it had less than a second.

TellGRBill

i'M NOT SURE WHAT "TIME DELAY" MEANS.

BB.

Usually it is a function that waits for the voltage to fall below the trip point for X amount of time. I.e., when starting your pump, the battery bus voltage may fall to 10.5 volts (dead battery range), but once the motor is up to speed, the voltage rises to 11.5+ volts--Normal operational range for battery under load.

This stops you from "false trips" cutting out your power--Or causing cycling (pump surges, power cut, power on, pump surges, power cuts, ....).

You care less about voltage drops during surges... What really matters (for battery state of charge) is the steady state current and the voltage measured.

-Bill

TellGRBill

THANK YOU   BB

TellGRBill

I think I found where the $100 12v to 220v  inverter came from.

I believe the seller bought several from alibaba.com and was trying to make a few dollars.

https://www.alibaba.com/trade/search?spm=a2700.galleryofferlist.0.0.182c2a44hb8Tud&fsb=y&IndexArea=product_en&keywords=dealers+12v+-+220v+inverters+4000+watt&tab=all&&page=3

I found it advertised on Facebook Marketplace being sold by someone living close to me.

After asking several questions about the item, the seller stopped answering.