Another new guy with questions

MarkG · October 2011

Hello All,

Well, like others here, I am just starting out with a solar setup. I wanted to get people's take on what they think of the following:

Samlex SA-1500-112 12V 1500 Watt DC/AC Pure Sine Wave Inverter
Morningstar Prostar 30M charge controller
2 x Uni-Solar PVL-68T 68 Watt Laminate panels.
I haven't looked at batteries yet.

My questions are:
- Is Samlex a good brand? I was looking at a similar Go Power inverter as well, but it looks like they might actually be using a Samlex unit with their own labeling.

- The Prostar 30M can't control the frequency of battery equalization, and only equalizes up to 15.1 volts. Is this a big deal?

I realize the panels are small and they are not all that powerful, but for now they will do. If I bought the higher output laminate panels they would be too long.

My immediate needs would be having the ability to have emergency lighting (in multiple rooms) and possible run a TV/DVD player during power outages. I know some will say I can get away with a smaller inverter, but I like the ability to run other things as well, as the need arises.

I realize there is a lot to consider when selecting solar components, so any input from people would be greatly appreciated.

Regards

Mark

mike95490 · October 2011

Re: Another new guy with questions

Here's what I did with a single unisolar 64w panel

My Solar Monolith:

attachment.php?attachmentid=384&stc=1&thumb=1&d=1234752636

attachment.php?attachmentid=385&stc=1&thumb=1&d=1234752653

Update pictures/information here.

niel · October 2011

Re: Another new guy with questions

samlex is ok to use. not sure of go power's cost or reliability, but there are others out there like one from xantrex that are cheap too.
http://www.xantrex.com/power-products/power-inverters/prowatt-sw.aspx
derate them by about 10% for their max and you'll be fine. i don't see the need for an inverter as large as you propose unless you intend something like a refrig or air conditioner, but then you'll need far more in batteries to run the stuff and more in solar power to charge them.

it can be a problem if the battery needs to be eqed above that voltage. if your system is to be portable, ie, moved around, then consider an agm as it's a sealed battery. you can do it with fla types if one is careful though. the agms won't have to normally be eqed btw.

you will have to watch yourself when it comes to power usage as the pvs you have will work ok with most group 27 and 31 type deep cycle batteries in and around 100ah. because you will adversely affect the life of a battery if you drain it consistently low we don't recommend draining it below 50%. this limits you to roughly 50ah usable on a 100ah battery or 600 watthours. also high current loads like refrigs or air conditioners will pull a battery's voltage way down even when the high load is only a brief surge so large loads need the larger battery power behind it.

MarkG · October 2011

Re: Another new guy with questions

Thanks for the response guys.

Mike, that's an interesting idea, I like the portability you have there.

Niel, thanks for the info, it's appreciated. It looks like I have some more research to do before I jump into this.

Regards

DavidOH · October 2011

Re: Another new guy with questions

1500 watts? That inverter is definitely overkill.

If you use a 12volt TV/DVD player, and all 12v lighting, you could go without the inverter.

Examples:
http://www.walmart.com/ip/Viore-26-LED26VF55D/15705880
http://www.walmart.com/ip/Sceptre-19-E195BD-SHD/16935878

These LCD/LED TVs use about 50 watts. (I assume that is with the DVD player running)

There are lots of options on 12v lighting, including LEDs.

MarkG · October 2011

Re: Another new guy with questions

Thanks David, I didn't think about the 12 Volt stuff, sometimes the simpler solutions elude us at times. I still want AC from an inverter, but I will look at a smaller unit as my needs wouldn't really justify the 1500 watt unit. Regards -Mark

BB. · October 2011

Re: Another new guy with questions

For an efficient small TSW inverter--I would really suggest the 12 volt 300 watt MorningStar model. Very nice for use with a smaller/lower power 12 volt system.

-Bill

bmet · October 2011

Re: Another new guy with questions

I didn't read anything about the listed examples that mentions 12V operation. Where in the product description is it?

DavidOH wrote: »

1500 watts? That inverter is definitely overkill.

If you use a 12volt TV/DVD player, and all 12v lighting, you could go without the inverter.

Examples:
http://www.walmart.com/catalog/product.do?product_id=16207343&findingMethod=rr#Item+Description
http://www.walmart.com/catalog/product.do?product_id=16332837&findingMethod=rr

These LCD/LED TVs use about 50 watts. (I assume that is with the DVD player running)

There are lots of options on 12v lighting, including LEDs.

DavidOH · October 2011

Re: Another new guy with questions

Someone else turned me on to 12v powered TVs.

Most of the details you won't find on the retailers website.
You have to go to the manufactures website. You do get a clue when you see the external power supply. Often they have a picture of the back of the TV.

That is helpful if you can eliminate the inverter losses.

I have gotten everything in my building project down to 12 volts except the refrigerator. That's only 85 watts, so I can use a small inverter.

MarkG · October 2011

Re: Another new guy with questions

Thanks Bill, as well as others for your suggestions.

Well, I went with the Xantrex Prowatt SW1000 true sinewave inverter, a Xantrex C40 charge controller, and two Uni-Solar 68W panels.

Some may think the C40 is overkill and maybe it is, but I liked it's ability to handle 12, 24, and 48 volts for future upgrades.

I have not purchased batteries yet, however, so that is next on my list. Have to do some more research on flood vs agm vs whatever.

Best regards.

-Mark

MarkG · November 2011

Re: Another new guy with questions

Hi Niel, I see you are using Sun Xtender PVX-1040T batteries. How do you like their performance? Any issues with them? I am ready to add batteries to my solar build-out and just want people's take on what they use. Thanks in advance. - Mark

niel · November 2011

Re: Another new guy with questions

mark,
in a nutshell, i love them. only 2 drawbacks are the cost and being sure the voltage does not go too high. your wallet takes care of one and the controller is supposed to take care of the other. you will see jumps beyond the max voltage with a c40 and i know this first hand, but i don't leave mine connected 24/7 and that jump occurs when i suddenly feed it full power from the pvs rather than gradual jumps through the day. this overvoltage jump can happen also when it is very dark from nasty weather and then go to full sunshine. i use the c40 on my older pvx1040t reserved for ham radio use and i watch the overvoltage and disconnect momentarilly at that time to allow it to quickly settle to the good voltage range and if it goes back over again i repeat this until it settles. for the new agms i use a classic mppt controller.

MarkG · November 2011

Re: Another new guy with questions

Thanks Niel, wow, bummer. Some questions if you don't mind? Do all PWM controllers do that or is it just that the C40 is poorly engineered, in your opinion? What is the voltage that you consider high from the C40? Lastly, what do you think of the Morningstar SunSaver SS-MPPT-15L? What's the point of employing the C40 if it has to be babysat? I feel like I wasted some money. Thanks again!

niel · November 2011

Re: Another new guy with questions

i can't speak for all pwm controllers as i haven't had them all. i know the pwm sunsavers hold their voltage pretty well, but they lack the float stage and as such i do not advise using them. maybe some of the others can chime in with their experiences on their controllers.

waynefromnscanada · November 2011

Re: Another new guy with questions

niel wrote: »

i can't speak for all pwm controllers as i haven't had them all. i know the pwm sunsavers hold their voltage pretty well, but they lack the float stage and as such i do not advise using them. maybe some of the others can chime in with their experiences on their controllers.

I've used Morningstar's SunSaver MPPT controller and loved it. The MPPT version does have float mode. Why did I quit using it? My input voltage was at times nearing the recommended max of 75 volts. What did I replace it with? Morningstar's TS-MPPT-60.
Here's a link to the MPPT Sunsaver owners manual:
www.morningstarcorp.com/en/support/library/SSMPPT.IOM.EN.02.pdf

niel · November 2011

Re: Another new guy with questions

he is using an agm and a constant absorb can't be good for them. fla types can take the constant absorb fairly well i think. how about their other pwm ccs that are tristar?

Cariboocoot · November 2011

Re: Another new guy with questions

niel wrote: »

he is using an agm and a constant absorb can't be good for them. fla types can take the constant absorb fairly well i think. how about their other pwm ccs that are tristar?

Just recently there was another poster looking at the MS Sunsaver. Seems the new ones do 3 stage charging: Manual http://www.morningstarcorp.com/en/support/library/SS3.IOM.Operators_Manual.01.EN.pdf
Look at page 15; it lists Absorb Float and EQ Voltages for FLA's.

The Tristar is listed as "4 stage charging" on the spec sheet. Likewise the Prostar series lists Float Voltage settings.

niel · November 2011

Re: Another new guy with questions

thanks for pointing that out coot. they list the float as 13.7v which is way too high for my sunextenders. i think more adjustability would be warranted for proper agm use.

MarkG · November 2011

Re: Another new guy with questions

Hi Niel, just a reminder, I am not using any agm batteries as I haven't purchased them yet. That is why I was inquiring as to what other people were using. I do own the Xantrex C40 and it appears it isn't well suited to agm batteries from what I am hearing, although the manual says it is or maybe it's just the sunextender batteries it has an issue with? I'll have to look into it. Thanks.

BB. · November 2011

Re: Another new guy with questions

As a complete aside--I have read a couple times here that the CXX family of controllers has just stopped working after a year or three. I thought these were pretty bullet proof controllers--But, like everything solar, you have to keep an eye on the system to avoid killing the battery bank.

Towards this end, a battery monitor is really a nice option... Darn near required for AGM/Sealed batteries.

-Bill

MarkG · November 2011

Re: Another new guy with questions

Hi Bill, I am using the front panel meter option with the Xantrex C40. What does a battery monitor provide for me that the panel meter does not?

Also, I think I made a newbie mistake. I designed my system around 12V when I should have went for 24V I am thinking. I have two 68W 12V panels and to keep the runs to a minimum, I was thinking of stringing the panels in series for 24V. This also keeps the required wire gauge size down for a lengthy run I believe. The question I have is can I still keep a 12V battery setup (from the charge controller perspective)? The reason being my inverter is 12V. So to recap, I would like to know if there are any issues running 24V panels to the charge controller and then 12V out to the batteries? It may not be an ideal setup, but can it be done without issue?

Cariboocoot · November 2011

Re: Another new guy with questions

Short answer: no.

Your Xantrex C40 controller is a PWM type. It does not have the ability to down-convert the higher Voltage from the "24V" panels to extra current @ 12 Volts. In essence you'll be throwing away half your power.

BB. · November 2011

Re: Another new guy with questions

A battery meter places a "shunt" (precission power resistor) between the battery negative post and the rest of the power wiring.

So, any current that flows into or out of the battery bank is measured by the resistor:

Deltec 500 amp, 50 millivolt current shunt

The battery monitor is a precision volt meter that measures the voltage drop across the shunt.

In addition, there is a clock in the battery monitor too... Basically, if you draw 10 amps for 1 hour, then the monitor shows the battery is -10 AH from full... If you pump 10 amp for 1 hour back into the battery bank it is now 0 AH from full.

Normally, a battery monitor lets you program the size of the battery bank (example: 100 AH battery -10 AH down, is 90% charged).

Also, batteries are not perfect and have losses. So, there are various parameters that you can set (or the monitor can determine) to reset back to 100% full (say it "sees" 14.5 volts for 2 hours, then reset back to 100%).

And a few battery monitors have an output that can be programmed to turn on or off based on state of charge (and perhaps another parameter--depending on brand and model).

A solar charger digital meter can only measure voltage and (typically) current it outputs to the battery bank. It does not know (for example) if the 10 amps it is outputing is going 100% to the battery bank or 50% to the load and 50% to the battery--So any battery capacity is "assumed" by the meter (usually voltage levels, time at voltage, and sometimes output current--which can be "confused" by loads).

So... The Battery Monitor (Victron also has some good review here) is quick and fairly accurate way of estimating the state of charge of the battery bank without using a hydrometer (cannot be done with a sealed battery) or by measuring resting voltage (3-24 hours of no charging/discharging).

For a house with spouse, children, guests--It is a lot easier to say "look at the meter"--If it is below 50% state of charge, start the generator (or cut back on loads) and run the genset until >80% state of charge (ideally early in the morning and let the solar panels continue the charging for the rest of the day).

And if you see the battery bank approaching 20% state of charge--turn off loads (check generator) and call you to find out what is wrong... The battery bank is in danger of being damaged.

Regarding the solar array... First, what is their Vmp? You want Vmp~17.5 to 18.5 for a 12 volt bank and ~35-37 volts for a 24 volt bank--for optimum charging with a PWM controller.

If you want a >22 volt Vmp array to charge a 12 volt battery bank, you should be looking at a MPPT type charge controller (more expensive type of controller).

Depending on brand and model, they will take Vmp>=17.5 volts to much higher (35 to 100+ volts, depending on controller specifications) and efficiently down convert it to the 14.5 volts needed to recharge your battery bank.

There are some "gotcha's" in there (a Outback controller with Vmp=100 volts and Vbatt=12 volts is, apparently, not very efficient... Also there are some 48-70 volt Vmp solar panels that cannot be used on 48 volt battery banks because their specifications do not "work" with most MPPT charge controllers).

Very roughly, if you choose to run the C40 (PWM) charge controller with Vmp~35 volts, it will work, but about 1/2 of the energy from your solar panels will be lost due to the voltage mismatch (Vbatt~14.5 volts; Vmp-array~35 volts).

Basically, the charging current from two panels in series to a 12 volt battery bank will be the Imp of the one panel (current in = current out for a PWM charge controller). A MPPT charge controller is a constant power device (ignoring losses). So P=Vmp*Imp=Vbatt*Ibatt -- If you double Vmp of the array, then Ibatt will have to double to keep the equation (balanced).

Hope that is clear.

-Bill

MarkG · November 2011

Re: Another new guy with questions

Thanks Cariboo and Bill, great write-up. To answer your question about Vmp for the panels, they are listed at 16.5Vmp. I was afraid of that, regarding the mismatch. What I will do is see if I can trade the 12V inverter in (wasn't used) for a 24V model. Failing that, I will have to stick with the 12V setup. Thanks again!

BB. · November 2011

Re: Another new guy with questions

More than likely, you are going to need larger panels and there is a good chance that their Vmp is not going to be around 17.5-18.5 Volts (for 12 volt battery, 2x for 24)... So, I would suggest:

Rogue 30 amps 12/24 volt MPPT controller
Morningstar SunSaver 15 Amp MPPT Solar Charge Controller (get the Remote Battery Temperature Sensor)

Of course, there are larger MPPT controllers too...

-Bill

MarkG · November 2011

Re: Another new guy with questions

Ah, the things you learn when you first start out...expensive lessons.

If you had to choose between the following, which would you go for? Yes, I know it's overkill for my panels, I was just curious about brands and possibly building out my system at a later date.

Outback FLEXmax 60
or
Morningstar TriStar MPPT-60

I am liking the Rogue unit you listed as well. What do you know of it's quality/reliability? Thanks again.

BB. · November 2011

Re: Another new guy with questions

Any of those would be fine... The MorningStar 60 amp MPPT has a small Internet server inside... Newer design. MorningStar is one of the few vendors that has remote voltage sense leads (on higher end TS family controllers) for accurately measuring the battery bank voltage (no problem with voltage drop in charge controller connections).

The Rogue is very cost effective smaller unit (no "digital meter options", etc.)--although its input voltage is (as I recall) limited to roughly 2x12 volt panels in series... From what I have read here--nobody has had any issues yet. New upgrade with a few more features (I really like the remote voltage sense feature).

Outback has been well known for years. Many people are very happy with them. Lots of options and connectivity between controllers, inverters, etc...

Should also research the Midnite Solar "Classic" if you are looking at higher end controllers.

In any case, my system is grid tied--So, you should read through the specifications/manuals and see what meets your needs best. There are many people here with more experience with the various pieces of hardware that can answer your questions.

In the end, if you are building out a smaller system--I would suggest avoiding over buying larger than useful hardware (both charge controllers and inverters)... There can be significant efficiency losses if you run some of the larger controllers with smaller arrays (say less than 400 watts or so).

Also, there may be efficiency issues with Vmp-array at upwards of 80-100 volts charging a 12 volt battery bank (I think this was with an Outback MPPT charge controller--but could be an issue with others--need to read the manuals closely).

Sorry--But this is about as much as I can help in this area.

A solar PV system can be fairly complex--Most devices have on-line versions of their manuals, so read through them closely and feel free to ask questions here about specific choices--It is usually easier for us to discuss a specific setup's strengths and weaknesses vs trying to see what gets tossed and sticks on the wall.

-Bill

Another new guy with questions

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