Just getting started

[jsemon]

Currently installing a solar setup for my building. It's already wired to the grid but I have been interested in playing with solar and thought I'd build a separate setup to power random things in the building from solar instead of using grid. All I'm going to be running is a TV, light, mobile devices, fan and treadmill. Not all at once but that'd be everything I will ever use in there. I have 2-12v panels going to a 40amp mppt charge controller feeding a 12v 100ah battery that feeds a 1000w pure sine wave inverter. I have everything wired in with fuses and just haven't mounted the panels yet so they're not connected. My question to the group was my sizing of wire from the solar panels to the controller. I purchased these 10ga 20ft extensions and that is what comes from outside to the controller. I haven't mounted them yet and have the option to move the closer but think I will have better sun exposure where the extension gets me. Is 10 ga good enough for that length. I have attached the specs for the panels.

 

[sunshine_eggo]

That is NOT a MPPT controller. It's a PWM controller. It's a known fake. This means you MUST only use "12V" panels, and they MUST be in parallel.

The breakers you have appear to be cheap audio system type breakers and are not suitable for use in most cases. If that's a LFP battery, a class T fuse is typically recommended. Breakers can work, but the breaker AIC rating needs to be > 20,000A.

10awg is good for 30A, and your array will never output more than 10.4A Isc (two panels in parallel).

You can calculate your own voltage drop here:

Voltage Drop Calculator

This free voltage drop calculator estimates the voltage drop of an electrical circuit based on the wire size, distance, and anticipated load current.

www.calculator.net

Use the Estimated Resistance tab.

 

[jsemon]

Thank you I'm new to it and appreciate your insight. I will definitely replace the fuses and will probably change out the controller as well. This is a great resource to have and thanks for the help.

 

[sunshine_eggo]

Thank you I'm new to it and appreciate your insight. I will definitely replace the fuses and will probably change out the controller as well. This is a great resource to have and thanks for the help.

Sticking with the brands/models in this page will help you avoid encountering the same shennanigans:

DIY Off Grid Solar Charge Controllers

Building a vehicle mounted solar power system? Let me help.

www.mobile-solarpower.com

 

[Rednecktek]

With very few exceptions, if it has USB ports it's a FAKE and really just a PWM.

 

[jsemon]

I did get the victron 30amp Bluetooth controller and switched out the switches for more suitable ones like the thread said. Also stuck a class t fuse in and have more to add to make it better. I'll add pics next time I'm in the building to see what else I can do. I have everything running and I have noticed that my charge controller is telling me hi and low battery level and twice I've seen my 12v 100ah battery show the highest voltage at 16.2 one day and another at 16.5. Not sure why if my settings on the controller are for 14.2 absorption and 13.5 float would it get that high. I'm not in there much during the day so it isn't used much and mainly at night. I have currently 2 - 12v panels in parallel and bout to more but wonder if I'm throwing too much into the battery and shouldn't add more. I just thought the controller would prevent over charging. I haven't messed with the expert settings and maybe that's the key but I'm new to this and left the default for life po4 in play. Any suggestions would be greatly appreciated.

 

[sunshine_eggo]

I did get the victron 30amp Bluetooth controller and switched out the switches for more suitable ones like the thread said. Also stuck a class t fuse in and have more to add to make it better. I'll add pics next time I'm in the building to see what else I can do. I have everything running and I have noticed that my charge controller is telling me hi and low battery level and twice I've seen my 12v 100ah battery show the highest voltage at 16.2 one day and another at 16.5. Not sure why if my settings on the controller are for 14.2 absorption and 13.5 float would it get that high. I'm not in there much during the day so it isn't used much and mainly at night. I have currently 2 - 12v panels in parallel and bout to more but wonder if I'm throwing too much into the battery and shouldn't add more. I just thought the controller would prevent over charging. I haven't messed with the expert settings and maybe that's the key but I'm new to this and left the default for life po4 in play. Any suggestions would be greatly appreciated.

Voltage spikes are indicative of BMS charge protection events, i.e., your battery cells are imbalanced - The BMS senses one cell going over voltage before the battery reaches 14.2V, cuts off the charge, and the charger can't clamp down to zero before a small voltage spike occurs.

Lower absorption to 13.8V, set fixed absorption time to 2 hours. Should reduce/eliminate protection events, and the cells will eventually balance out.

 

[jsemon]

Thanks, I made the changes and attached the settings from the controller as of now, I see that by default the equalization option is off so I left it and assume it isn't used for these batteries.

 

[sunshine_eggo]

Correct. Equalization is only for flooded lead acid. However, it can be used with LFP for a periodic "balancing" charge.

Many choose to operate their LFP batteries to a lower voltage like the 13.8V I recommended as you can get to very nearly fully charged if not truly fully charged at the expense of a longer absorption period.

One could use the equalization charge to push the battery to 14.4V every two to four weeks for 2 hours or something like that. It's been discussed several times, but I'm not aware of anyone actually implementing it. For a DIY battery, or a BMS that you can reprogram the balancing parameters, it's likely not necessary. For a "canned" battery that is a black box inside, with unknown balance critieria, it might be beneficial if the battery spends a few hours at peak voltage every month to ensure cell balance is maintained.

A periodic equalization charge to 14.4V would also identify if there are any balance issues. If it makes it to 14.4V without a spike, then it's balanced.

Again, this has been discussed, but I'm not aware of it being implemented.

 

[jsemon]

New question.

Same setup
2 Eco worthy 12v 100w panels(parallel)
30/100 victron Bluetooth mppt
Litime 12v 100ah life p04 battery

Recently purchased 2 more panels, same ones. From my understanding if I go more than 2 parallel I need to put inline fuses for each one. Short circuit current states 6.11a, but there is no description of fuse sizes for protection. I will have 4 in parallel (m#L02M100) and each will need a fuse, is it safe to assume that a 10amp mc4 fuse on each is appropriate? Also I already have 2 - 15amp mc4 fuses and will that be ok to use on 2 of them? I have all four connecting outside and from that connection I have a 20ft 10ga extension coming inside where I will eventually add a 30amp breaker. Also will it be bad to use 4 panels I have read 3 is sufficient for my one battery. I may expand to more but my understanding was the charge controller would limit it and extra just goes no where.

 

[sunshine_eggo]

10A or 15A (mix 'em up as you like) MC4 on each panel's (+) MC4 lead should be fine.

MPPT 100/30 datasheet:

https://www.victronenergy.com/upload/documents/Datasheet-BlueSolar-charge-controller-MPPT-100-30-&-100-50-EN.pdf

100Voc max
35A PV isc max ("PV input current limit")

You are under both, so you are not excessively over-paneled.

Your battery should be rated for 50A charge with optimal health being around 20A, so you're good there too as the MPPT has an absolute maximum output of 30A.

 

[Bluedog225]

I’m a little curious about your set up. Particularly wire size and your class T.

And welcome to the forum!

 

[jsemon]

Awesome thanks I'll get 2 - 10amp fuses for the other 2 and get them connected. Any recommendations for the battery monitor. I was thinking the 500 amp victron smart shunt. The price tag is high but thought it might be better with the victron controller as they might communicate with each other and streamline start and stopping the charge as it reaches 100%. Currently I don't have the battery monitor installed and worry about the charging process without it and if the charge controller itself is sufficient for charging and maintaining the charge without it.

 

[jsemon]

1000 watt inverter

4ga wire from battery to inverter with 100amp class t fuse and switch

8ga from mppt to battery with 40amp dc breaker, will be adding 30amp breaker before mppt to turn off panels when needed

 

[jsemon]

I’m a little curious about your set up. Particularly wire size and your class T.

And welcome to the forum!

1000 watt inverter

4ga wire from battery to inverter with 100amp class t fuse and switch

8ga from mppt to battery with 40amp dc breaker, will be adding 30amp breaker before mppt to turn off panels when needed

 

[sunshine_eggo]

Awesome thanks I'll get 2 - 10amp fuses for the other 2 and get them connected. Any recommendations for the battery monitor. I was thinking the 500 amp victron smart shunt. The price tag is high but thought it might be better with the victron controller as they might communicate with each other and streamline start and stopping the charge as it reaches 100%. Currently I don't have the battery monitor installed and worry about the charging process without it and if the charge controller itself is sufficient for charging and maintaining the charge without it.

Yes. Smartshunt with temp sensor. VE.Smart network between the two gives the MPPT actual battery voltage, current and temperature.

The charging process is essentially identical with or without, it's just more accurate with.

 

[jsemon]

Yes. Smartshunt with temp sensor. VE.Smart network between the two gives the MPPT actual battery voltage, current and temperature.

The charging process is essentially identical with or without, it's just more accurate with.

Thanks for the help that's where I was leaning but other people had used different brands because of price tag. I'll get the victron and do it right.

 

[sunshine_eggo]

Thanks for the help that's where I was leaning but other people had used different brands because of price tag. I'll get the victron and do it right.

The price recently dropped from $130 to $117 on amazon. At that point it's only about $30-40 more than options with fewer features.

Will lists a few on his website including the smartshunt (his top pick, $117). There's also the AiLi ($50) and one with a hall effect sensor ($35) (I have this one for test bench purposes). The added features of the smartshunt and it's ability to network with the MPPT make it a much better value.

 

[jsemon]

The price recently dropped from $130 to $117 on amazon. At that point it's only about $30-40 more than options with fewer features.

Will lists a few on his website including the smartshunt (his top pick, $117). There's also the AiLi ($50) and one with a hall effect sensor ($35) (I have this one for test bench purposes). The added features of the smartshunt and it's ability to network with the MPPT make it a much better value.

Thanks I ordered it from the link here to do my part and contribute. Thanks again for all your insight.

 

[jsemon]

New question, so I have the victron 500amp smart shunt and am ready to put it in place. However the issue I have is that I have wires that come from the mppt that connect directly to the negative on the battery and another wire that connects from the battery to the inverter. I know the shunt goes on the negative line and my plan was to break the line between the battery and inverter and have it there. I think that I should have it wired differently to pick up the incoming from the mppt for it to be accurate but would require more rewiring to rearrange the circuit. My question is if I do this will it be accurate or will It be bad without sensing the incoming directly through the shunt.