Help with my system please

[Aradia]

Hello all,
I am new here and would like some advice about my new system
I have:
three 136 watt Unisolar flexible solar panels each voc 46.2-42.2 They are supposedly for either 12 or 24 systems. http://www.soldonsun.com/files/UNI-PVL136.pdf
two 100 ah 12 volt Ocean sealed lead acid deep cycle batteries to be wired in series for my
24 v 1500 watt inverter

I also have a Morningstar MPPT Sun Saver 15 charge controller. Max open circuit voltage 75 v Battery Voltage Range 7-36 volts
• Nominal Maximum Operating Power*
12 volt battery 200 Watts
24 volt battery 400 Watts

http://www.morningstarcorp.com/wp-content/uploads/2014/02/SSMPPT_ENG10_1111.pdf

My question is whether or not my charge controller is strong enough to wire the 3 panels in series and if that is even necessary. I get approximately 4.5 hours of sun in my zone however it is a bit shady part of the day due to some tall trees. I may get either a stronger charge controller and probably another battery in the future. Would I be able to get just as good battery charging by wiring the 3 panels in parallel in low light Winter conditions ? Also, do I need to vent my battery box for sealed lead acid batteries?
thank you in advance

[lkruper]

Hello all,
I am new here and would like some advice about my new system
I have:
three 136 watt Unisolar flexible solar panels each voc 46.2-42.2 They are supposedly for either 12 or 24 systems. http://www.soldonsun.com/files/UNI-PVL136.pdf
two 100 ah 12 volt Ocean sealed lead acid deep cycle batteries to be wired in series for my
24 v 1500 watt inverter

I also have a Morningstar MPPT Sun Saver 15 charge controller. Max open circuit voltage 75 v Battery Voltage Range 7-36 volts
• Nominal Maximum Operating Power*
12 volt battery 200 Watts
24 volt battery 400 Watts

http://www.morningstarcorp.com/wp-content/uploads/2014/02/SSMPPT_ENG10_1111.pdf

My question is whether or not my charge controller is strong enough to wire the 3 panels in series and if that is even necessary. I get approximately 4.5 hours of sun in my zone however it is a bit shady part of the day due to some tall trees. I may get either a stronger charge controller and probably another battery in the future. Would I be able to get just as good battery charging by wiring the 3 panels in parallel in low light Winter conditions ? Also, do I need to vent my battery box for sealed lead acid batteries?
thank you in advance

A few observations, not necessarily what you have asked:

1) Your inverter is too big for your battery bank. A rule of thumb is Inverter Watts / AH <= 2. Your number is 15. Here is why: Your 1500w inverter can draw 63 AH @ 24v from your 100 AH 24v battery bank. If you take your battery down to 50%, it will take only 37 minutes. The potential discharge rate on your battery may be too high for even your sealed batteries, check the technical manual for that manufacturer.

2) Your panels put out, with no efficiency loss, 408W, which is 17 AH @ 24v. That is 0.17C, but with 86% efficiency, and even some more loss from your charger controller (95%) that could reduce your AH to 14 AH or less, which is only 0.14C. Some AGM batteries like Concorde specify that is one takes their batteries down to 50% DOD, that they should be charged at least 0.2C.

3) Your batteries will charge no faster than 3.5 to 4 hours in bulk and take at least another two hours in absorb which brings it to 5.5 or 6 hours. Most places don't have that kind of insolation in the winter and some not even in the summer.

Don't be fooled by my title Solar Fanatic Check my numbers, I have no real experience, but hope to soon and hopefully get my math skills up to snuff first.

[lkruper]

The footnotes of your panels also read: During the first 8-10 weeks of operation, electrical output exceeds specified ratings. Power output may be higher by 15%, operating voltage may be higher by 11%
and operating current may be higher by 4%.

Also, I now see you say you get 4.5 hours of sun in your zone. Depending on where you get that number from, it may not really be equivalent to solar insolation. Your MPPT controller will handle getting the voltage to the right level with your panels in parallel. You will need fuses if you wire your panels in parallel.

Sealed batteries do have the potential to allow gases to escape. I have seen battery boxes recommended by AGM manufactures... I would read their manual for that.

Now I see that your charge controller is only rated at 15 amps. That is probably low for your AGM batteries, check the manual.

[Aradia]

A few observations, not necessarily what you have asked:

1) Your inverter is too big for your battery bank. A rule of thumb is Inverter Watts / AH <= 2. Your number is 15. Here is why: Your 1500w inverter can draw 63 AH @ 24v from your 100 AH 24v battery bank. If you take your battery down to 50%, it will take only 37 minutes. The potential discharge rate on your battery may be too high for even your sealed batteries, check the technical manual for that manufacturer.

2) Your panels put out, with no efficiency loss, 408W, which is 17 AH @ 24v. That is 0.17C, but with 86% efficiency, and even some more loss from your charger controller (95%) that could reduce your AH to 14 AH or less, which is only 0.14C. Some AGM batteries like Concorde specify that is one takes their batteries down to 50% DOD, that they should be charged at least 0.2C.

3) Your batteries will charge no faster than 3.5 to 4 hours in bulk and take at least another two hours in absorb which brings it to 5.5 or 6 hours. Most places don't have that kind of insolation in the winter and some not even in the summer.

Don't be fooled by my title Solar Fanatic Check my numbers, I have no real experience, but hope to soon and hopefully get my math skills up to snuff first.

LKruper thank you for the response. Let me try to see if I understand what you are saying. I need to get some more batteries, I should wire in parallel with fuses and I do need a battery box. I could not understand some of what you were saying like what solar isolation means. Did I miss some of your points? If so can you dumb it down a bit for me please?
thank you so much for your help

[lkruper]

LKruper thank you for the response. Let me try to see if I understand what you are saying. I need to get some more batteries, I should wire in parallel with fuses and I do need a battery box. I could not understand some of what you were saying like what solar isolation means. Did I miss some of your points? If so can you dumb it down a bit for me please?
thank you so much for your help

You should not buy anything yet. You must first define your load. Decide what you want to run and how long. This will require some effort on your part, but it is critical to do so or you won't succeed. Secondly, before I forget, you do not need more batteries right now because at this point it does not look like your panels and charge controller are large enough for your batteries. Before we know this, you need to check with the manufacturer of your batteries.

Secondly, your inverter is too big for the batteries. This is a dangerous condition whereby you could try to power too much load which could not only damage your battery but also potentially start a fire.

Do you have this system already set up and are you running anything from it? If so, what and how long?

[Aradia]

I have not had the ingredients installed yet. I am planning to test it all out in a few days. So what I am hearing now is that I need to upgrade the charge controller and get a few more panels after I decide how much I will be running off the system.
I HOPE to power a 125 watt tv, 38 watt dish network hopper (a few hours/day) , 6 watt modem (12 hours), 45 watt laptop, one 10 watt LED light.

[thastinger]

I have not had the ingredients installed yet. I am planning to test it all out in a few days. So what I am hearing now is that I need to upgrade the charge controller and get a few more panels after I decide how much I will be running off the system.
I HOPE to power a 125 watt tv, 38 watt dish network hopper (a few hours/day) , 6 watt modem (12 hours), 45 watt laptop, one 10 watt LED light.

Just use the tool in the off-grid section, there have been countless that came here post install and found out the weren't anywhere near what they needed for a properly functioning system...load demand is the first calculation and a kill-a-watt meter helps with that.

[lkruper]

I have not had the ingredients installed yet. I am planning to test it all out in a few days. So what I am hearing now is that I need to upgrade the charge controller and get a few more panels after I decide how much I will be running off the system.
I HOPE to power a 125 watt tv, 38 watt dish network hopper (a few hours/day) , 6 watt modem (12 hours), 45 watt laptop, one 10 watt LED light.

Here is how you would calculate you needs:

125w tv X 4 hours +
38w dish hopper X 4 hours +
6w modem X 6 hours +
45w laptop X 6 hours +
10 watt LED X 12 hours
===============
500 +
152 +
36 +
270 +
120 =
=====
1078 wh / day

If you take your 100AH 24v battery down to 50% that leaves 50AH

1078 wh / 24v battery = 45 AH / day
But there is an inefficiency in the following:

Your inverter will be 80-90% efficient so
45 X 1/.8 =56 AH

Your big inverter also consumes power, the specs should show self-consume wattage.

You are a bit over 28%, not too bad.

Your panels and charge controller will need to supply:

56 AH X 1/ 0.86 panel inefficiency X 1 / .95 charge controller inefficiency = 69 AH
69 AH X 24v = 1656 Wh

From before your panels put out 408w

1656/408 = 4 hours

You say you have a marginal 4.5 hours but there is shade. Does that reduce the 4.5? You will need
5 hours to bulk charge + 2-4 hours for absorb.

You are light on charging, and don't forget your huge inverter is potentially a fire hazard.

Check my calcs

[Aradia]

Here is how you would calculate you needs:

125w tv X 4 hours +
38w dish hopper X 4 hours +
6w modem X 6 hours +
45w laptop X 6 hours +
10 watt LED X 12 hours
===============
500 +
152 +
36 +
270 +
120 =
=====
1078 wh / day

If you take your 200AH battery down to 50% that leaves 100AH

1078 wh / 12v battery = 89 AH / day
But there is an inefficiency in the following:

Your inverter will be 80-90% efficient so
89 X 1/.8 =112 AH

Your big inverter also consumes power, the specs should show self-consume wattage.

You are a bit over 50% but not too bad.

Your panels and charge controller will need to supply:

112 AH X 1/ 0.86 panel inefficiency X 1 / .95 charge controller inefficiency = 137 AH
137 AH X 12v = 1972 Wh

From before your panels put out 408w

1972 /408 = 4.8 hours

You say you have a marginal 4.5 hours but there is shade. Does that reduce the 4.5? You will need
5 hours to bulk charge + 2-4 hours for absorb.

You are light on charging, and don't forget your huge inverter is potentially a fire hazard.

Check my calcs

This is a wonderful breakdown for me I am very indebted to you. I will print this off and review it. You are teaching me a great deal by taking the time to show me this example. I highly appreciate it. Thank you so much

So if I purchase 2 more of these panels and the higher capacity mppt charge controller, I should be able to absorb more energy to be safer.
The next project I am thinking about is to change the heating elements in my hot water heater to Missouri Wind and solar 200 watt heating elements instead of the 12,000 watt (i think) elements, put a timer on the hot water heater so it only comes on for a short time in the morning for a shower and then shuts off for the whole day. I figure the water heated up in the tank will be luke warm by the end of the day. https://www.youtube.com/watch?v=iGCMwsDYmAw I may even switch over to one of those tiny refrigerators instead.
What do you think about these ideas? Maybe I will be able to cut consumption significantly if I do these things.

[lkruper]

This is a wonderful breakdown for me I am very indebted to you. I will print this off and review it. You are teaching me a great deal by taking the time to show me this example. I highly appreciate it. Thank you so much

So if I purchase 2 more of these panels and the higher capacity mppt charge controller, I should be able to absorb more energy to be safer.
The next project I am thinking about is to change the heating elements in my hot water heater to Missouri Wind and solar 200 watt heating elements instead of the 12,000 watt (i think) elements, put a timer on the hot water heater so it only comes on for a short time in the morning for a shower and then shuts off for the whole day. I figure the water heated up in the tank will be luke warm by the end of the day. https://www.youtube.com/watch?v=iGCMwsDYmAw I may even switch over to one of those tiny refrigerators instead.
What do you think about these ideas? Maybe I will be able to cut consumption significantly if I do these things.

Conservation should be the first thing you do, as it will save much later. On water heating, electric resistant heating is very expensive with solar. I would think at the equator you could use a different solar method to heat your water directly.

The AC/DC refrigerators are designed to take much less power and are a good choice if you can live with the smaller sizes. I would also encourage you to get the technical user manuals for all your equipment and learn them well. The details and safety features are indispensable. Check your system against what the battery manufacturer says about charging their batteries and the same goes with the solar panels and charge controllers, etc. Pay attention to fusing and wire size recommendations in your equipment.

If you have time, stick around and read the older and new posts on the subject. Compare different approaches from different people and make sure you know what you are doing before you start.

[Aradia]

Conservation should be the first thing you do, as it will save much later. On water heating, electric resistant heating is very expensive with solar. I would think at the equator you could use a different solar method to heat your water directly.

The AC/DC refrigerators are designed to take much less power and are a good choice if you can live with the smaller sizes. I would also encourage you to get the technical user manuals for all your equipment and learn them well. The details and safety features are indispensable. Check your system against what the battery manufacturer says about charging their batteries and the same goes with the solar panels and charge controllers, etc. Pay attention to fusing and wire size recommendations in your equipment.

If you have time, stick around and read the older and new posts on the subject. Compare different approaches from different people and make sure you know what you are doing before you start.

I do have a Square D 60 amp 2-Space 4-Circuit Outdoor Main Lugs Load Center with Non-Metasllic Enclosure and Neutral

a SQU QO15 15 AMP Circuit breaker

200A Square ANL Fuse Holder with 200A Fuse

Blue Sea Systems m-Series Mini On-Off Battery Switch with Knob- Red

Inline Fuse Holder

I plan to use this schematic roughly

http://tinhatranch.com/wp-content/uploads/2015/05/THR-400-W-Solar-System-SchematicR1.pdf

since the system has roughly the same numbers as my system.

Thanks for that. I have watched videos on youtube about how to wire the circuit breaker box. I think I put the positive wire from the solar panel on to the bottom of the circuit breaker, but I am a little sketchy on the wiring of the rest of the circuit breaker box. Also, I still did not get a ground kit off of amazon yet. I may leave off the circuit breaker until after I test the main parts of the system. I do know an electrician so I may just have him to do the circuit breaker box and the fuses once I've tested the bones of the system (panels, charge controller, batteries, inverter). I do feel very comfortable wiring the panels in parallel to the charge controller. And I have already tested the inverter on the batteries in series with a load plugged into the inverter. That part worked great, so I only have to get on the roof and put the 3 panels in parallel now and then later have the electrician over for the fuses and circuit box. Thank you so much for all your information. You've helped me with the formula for figuring out systems and so much more.
About the inverter being a fire risk, do you say that because a 1500 watt inverter generates a lot of heat or because you fear I may plug too many things into it?
I did read your comment on the matter:
"1) Your inverter is too big for your battery bank. A rule of thumb is Inverter Watts / AH <= 2. Your number is 15. Here is why: Your 1500w inverter can draw 63 AH @ 24v from your 100 AH 24v battery bank. If you take your battery down to 50%, it will take only 37 minutes. The potential discharge rate on your battery may be too high for even your sealed batteries, check the technical manual for that manufacturer."
And I am trying to work through what that means exactly. I imagine you're saying I need more batteries after i get more panels and a bigger charge controller to go with this size inverter

Also another question, about your formula inverter watts/ ah <=2.... if I use say 7 or 8 of these 100 amp batteries , i would then have 700 or 800 ah and that would be a 2 to 1 ratio that is needed? Or do I actually have to switch to a tiny 200 watt inverter? It really seems that a 200 watt inverter would be so small it would make it a waste of money to buy all this equipment imo

[lkruper]

I do have a Square D 60 amp 2-Space 4-Circuit Outdoor Main Lugs Load Center with Non-Metasllic Enclosure and Neutral

a SQU QO15 15 AMP Circuit breaker

200A Square ANL Fuse Holder with 200A Fuse

Blue Sea Systems m-Series Mini On-Off Battery Switch with Knob- Red

Inline Fuse Holder

I plan to use this schematic roughly

http://tinhatranch.com/wp-content/uploads/2015/05/THR-400-W-Solar-System-SchematicR1.pdf

since the system has roughly the same numbers as my system.

Thanks for that. I have watched videos on youtube about how to wire the circuit breaker box. I think I put the positive wire from the solar panel on to the bottom of the circuit breaker, but I am a little sketchy on the wiring of the rest of the circuit breaker box. Also, I still did not get a ground kit off of amazon yet. I may leave off the circuit breaker until after I test the main parts of the system. I do know an electrician so I may just have him to do the circuit breaker box and the fuses once I've tested the bones of the system (panels, charge controller, batteries, inverter). I do feel very comfortable wiring the panels in parallel to the charge controller. And I have already tested the inverter on the batteries in series with a load plugged into the inverter. That part worked great, so I only have to get on the roof and put the 3 panels in parallel now and then later have the electrician over for the fuses and circuit box. Thank you so much for all your information. You've helped me with the formula for figuring out systems and so much more.
About the inverter being a fire risk, do you say that because a 1500 watt inverter generates a lot of heat or because you fear I may plug too many things into it?
I did read your comment on the matter:
"1) Your inverter is too big for your battery bank. A rule of thumb is Inverter Watts / AH <= 2. Your number is 15. Here is why: Your 1500w inverter can draw 63 AH @ 24v from your 100 AH 24v battery bank. If you take your battery down to 50%, it will take only 37 minutes. The potential discharge rate on your battery may be too high for even your sealed batteries, check the technical manual for that manufacturer."
And I am trying to work through what that means exactly. I imagine you're saying I need more batteries after i get more panels and a bigger charge controller to go with this size inverter

Also another question, about your formula inverter watts/ ah <=2.... if I use say 7 or 8 of these 100 amp batteries , i would then have 700 or 800 ah and that would be a 2 to 1 ratio that is needed? Or do I actually have to switch to a tiny 200 watt inverter? It really seems that a 200 watt inverter would be so small it would make it a waste of money to buy all this equipment imo

I added up all the loads you defined and they came to 224w. When sizing a solar system it is very difficult to grow it later and keep everything balanced. If you plan on running more than the 224w, then it would be good to carefully calculate that. On the other hand, there are advantages to a smaller quality inverter. You can afford a UL listed inverter from a quality manufacturer with a good reputation. Most of the time, the smaller inverters consume less power with no load.

There is the danger that you or someone else will power more than the 224w you have listed, and that is a danger to your smaller batteries. How will you wire and terminate your equipment? 1500w / 24v = 63 amps. Look at some guidelines for how big your wires need to be to be used with 63 amps for the distance you are wiring. It will cost much more for bigger wires, but if you don't use them, someone could draw that much current and start a fire. In fact it is possible that a malfunction in a load could cause that sort of draw, isn't it? Then the full potential of that large inverter could overheat your batteries or wiring and start a fire.

I am not an electrician, so I really would not want to advise you on these sorts of details. But I am aware of some of the guidelines which raise red flags for safety.

Read this sticky -> http://www.solarpaneltalk.com/showth...Considerations

[Aradia]

I already have 2 gauge battery cables with 5/16 lugs. I have 60' of 10 awg cable that came with my panels although I am only running 10' from the roof. I have two 3 branch M3c connectors to join the 3 panels in parallel. I have a 25' roll of 4 awg cable just in case but I see no reason to use that. My charge controller, in line fuses and have screws to tighten on the tip of an exposed wire and everything else has 5/16 lugs to go between the charge controller and the batteries.

I see a formula online that says to use an inverter that is 1.2 -1.5x the solar panel array. Some say you can do 3x the solar panel watts. So since my solar panels are now 408 watts and I have ordered two more which will ultimately total 680 watts. 1.5x 680watts solar panels will call for a 1020 watt inverter. http://www.solarpowerworldonline.com...m-performance/ So it seems like something was off in the calculations that I'd need a 200 watt inverter.

[lkruper]

I already have 2 gauge battery cables with 5/16 lugs. I have 60' of 10 awg cable that came with my panels although I am only running 10' from the roof. I have two 3 branch M3c connectors to join the 3 panels in parallel. I have a 25' roll of 4 awg cable just in case but I see no reason to use that. My charge controller, in line fuses and have screws to tighten on the tip of an exposed wire and everything else has 5/16 lugs to go between the charge controller and the batteries.

I see a formula online that says to use an inverter that is 1.2 -1.5x the solar panel array. Some say you can do 3x the solar panel watts. So since my solar panels are now 408 watts and I have ordered two more which will ultimately total 680 watts. 1.5x 680watts solar panels will call for a 1020 watt inverter. http://www.solarpowerworldonline.com...m-performance/ So it seems like something was off in the calculations that I'd need a 200 watt inverter.

My design specification is to size the inverter to meet the needs of the load. Your load is 224w. If I had a system with those loads, I would probably get something like a 300w inverter. The best way to plan is to start with the loads, not buy panels, batteries and inverter first. The goal should be to run the necessary loads as efficiently, economically and safely as possible. At least that would be my goal.

[Aradia]

I have more loads like microwave, refrigerator,hot water heater, washer/dryer, but I was offering the minimum I would like the system to at least accomplish. Ideally I would like to run as much of all of that as possible. I don't want to limit myself to just a few lights, tv and a computer ultimately since I've already spent too much money to just get that amount of pay off. I already have all the panels etc except the last 2 which are on the way.