New to solar, installing on RV

I am in the process of installing solar on my Truck Camper (TC). I live in my TC four nights and three days per week. I need to camp in the stealth mode as much as I can.

I have a 2000 watt Honda, a 65 amp WFCO three stage smart charger/converter and one 100 amp Lifeline AGM battery. I use just under 30 amps per day, for three days, for a total of 90 amps.

I am installing two Kyocera KC-65 65 Watt Solar Modules (17.4V-3.75 amps each = 7.5 amps) and a Blue Sky SB2000E MPPT charge controller. I have several questions.

1 Will the charge controller and charger/converter play nice with each other if both are on at the same time, or must I turn one off to use the other?

2 Will the MPPT charge controller increase the charge to the AGM during overcast days?

3 What benefits should I expect from the MPPT charge controller?

4 Would adjustable panel mounts be a big improvement?

5 Any suggestions as to where I could find adjustable panel mounts for RVs?


Your input is valued and appreciated.


Wayne

Comments

  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: New to solar, installing on RV

    Wayne,

    1. The WFCO (World Freedom Company?) unit claims to be a three-stage charger, but the SB2000E is a two-stage charger (no float stage). Their various set-points may not be the same, and the SB2000E is (optionally) temperature compensated, while, to my knowledge, the WFCO is not. However, multiple chargers can generally coexist on the same battery bank. They may not operate at peak efficiency, but I doubt either will cause the other any harm. AGM batteries are sensitive to over-voltage charging, so you’ll want to follow Concorde’s instructions for the charger settings.

    2. Your PV modules will run cooler on mildly overcast days, so their output voltage should be somewhat higher. Accordingly, the “extra” voltage should be converted to additional charge current on such days. Don’t expect miracles.

    3. An MPPT controller’s main claim to fame is that it can convert most “extra” voltage (the difference between available PV voltage and battery charging voltage) into additional charging current. This extra voltage (which, times the PV current equals power, which, times time equals energy) is essentially lost when using a PWM controller (the PV array operates at battery voltage in the bulk charge mode).

    However, this extra voltage has to be available for the conversion to be made. The largest % charge current boost is typically realized early on a very cold day (relatively PV voltage high) while charging a discharged battery (relatively low battery voltage). As the day progresses, the sun warms the PV modules (PV voltage drops) and the battery voltage increases, the extra voltage reduces considerably, which results in little current boost.

    The Kyocera modules are fairly high voltage (STC Vmp = 17.4 V), and the Concorde AGM battery is a relatively low voltage battery (charging voltage = ~14.4 V), so you should see some current boost from the controller during the bulk charging stage, especially on cold days. This current boost should deliver a few extra Ah / day – perhaps 5% - 10% net after figuring the controller's internal losses (the SB2000E's eficiency spec is "typically 95% at 15 A output").

    The absorption stage is constant voltage / limited current, so the MPPT function is typically of no value in this charge mode unless you’re powering a load in parallel to the battery.

    In general, though, MPPT controllers are not cost effective in low-power configurations. The price difference between the SB2000E (and its optional enclosure and remote battery temp sensor) and, for example, a Morningstar SunSaver- or small ProStar controller could be invested in larger PV modules and you’d end up generating more energy. Ken Lenger originally included an SB2000E in his RV’s solar energy system, but he replaced it with a ProStar. You want to contact Ken and ask about his experience and rationale.

    4. Tilting your modules towards the South is usually beneficial. A tilt of latitude minus ~15 degrees will help cool and clean the modules in Summer, and a tilt of latitude plus ~15 degrees will help boost energy production in Winter. A tilt angle = latitude works well for Spring and Fall.

    5. Here’s a link to RV solar panel mounts available from NAWS, this site’s sponsor. Another possible source is RV Solar Electric.

    HTH,
    Jim / crewzer
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: New to solar, installing on RV

    The major reason (in my humble opinion) that MPPT controllers don't help much on small systems is that they use a significant amount of power to converter the power from input to output. So, on low power systems, any extra power that they may provide over a standard PWM controller may just be consumed by the internal conversion electronics.

    For example, the MX60 Outback controller--seems to be one of the best in the industry--open the following PDF file and look at its efficiencies on page 32. For power inputs over 500 watts, the it is better than 95%. For power inputs less than 125 watts, it heads quickly below 90% (which is the bottom of the graph). I don't remember exactly, but from looking at the graph the unit will consume somewhere between 25 and 50 watts before producing any power. Not a design flaw, just the nature of the beast.

    http://www.outbackpower.com/pdfs_manuals/mx60manualv5.00.pdf

    Another issue you will want to watch is that you don't consume for than, roughly, 50% of your battery capacity or you will damage its ability for a long life.

    Lastly, conservation is a good place to start with any system. I don't know what you are running or where your location is--but reducing power usage through efficient lights and appliances can help a lot too.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: New to solar, installing on RV

    BB,

    Good point re the controller's own efficiency -- I just can't remember everything all the time! :roll: :wink: I've edited my post above to somewhat account for this point.

    Speaking of the MX-60 and its operating efficiency, you may find these previous discussion topics to be of interest:

    http://www.wind-sun.com/smf/index.php?topic=1034.0 (Paricipant "boB" is Bob Gudgel, the MX' original designer from Outback)
    http://www.outbackpower.com/forum/viewtopic.php?t=952

    Wayne,

    Speaking of efficiency, good choice on the Concorde AGM battery! AGM battery Ah recharging efficiency is typically ~99%, vs. ~89% for regular ol' flooded-cell batteries.

    Regards,
    Jim / crewzer

  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: New to solar, installing on RV

    From reading the manual, the SB2000E MPPT controller takes about 0.09 amps (1 watt) of energy to provide the MPPT function. That is not a lot of energy.

    http://shop.altenergystore.com/pdfs/blue_sky/SB2000ttw.pdf

    From this article, the SB2000E was tested on a 165 watts of solar panels, pretty close to what you have:

    http://shop.altenergystore.com/pdfs/blue_sky/SB2000ttw.pdf

    I live just a mile off of the SF Bay (city of San Mateo), and according to the article, using a standard 12 vdc solar panel, you will will obtain, roughly, a 5% to 0% boost (55F to 80F). It does not get that cold here, so it is unlikely that you will get much more steady state boost.

    You are getting a 16% boost in your measurements, so (probably) while the panels are cool the MPPT is helping you.

    From this link, you can look up a city near your location (PDF or text files). It includes the data for five different tilts (0, lat - 15, lat, and lat +15 degrees):

    http://rredc.nrel.gov/solar/pubs/redbook/

    For San Francisco, you will get much more power by tilting your panels up (upwards of 50% in the winter, nothing gained in the summer--1 year average of ~15% gain for tilt at latitude over 0 degree tilt). Also, if you have panels tilted up, they will run cooler, and with MPPT, they will generate more power.

    So, the MPPT controller you are looking at seems fine (has battery temperature monitor, a very good thing to have), and can help you gain power in cool weather. And, combined with tilting your panels, will add to your overall power collection. It will be up to you if the price difference is enough to make it worthwhile (sounds like it is to me).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: New to solar, installing on RV

    Wayne,
    Your collective post indicate that the SB2000E MPPT charge controller will be of no benefit to a very small benefit.

    Correct.
    This raises the question of will it simply not be effective on a small system (130 watts), or will it take away from a small system?

    There are several mitigating factors here. One is that the 2000E’s operating efficiency is less that 100%. In addition to its “Charge On” power requirement (90 mA x ~14 V = 1.26 W), its specs also indicate that the power conversion efficiency is 95% at 15 A output. So, you’d need something between a 2% and a 5% current boost just to break even.

    Another factor is that any MPPT charging benefit is limited to the Bulk charging stage. The charger’s Absorption algorithm is fixed-voltage and declining-current, so there’s no MPPT benefit realized in this stage.

    A third factor is the PV module specs. The Kyocera KC-65’s STC Vmp spec is 17.4 V. Its typical Vmp will be lower, especially in your location, but there should be some “extra” voltage available for the 2000 to convert into additional Bulk stage charging current.
    Is the SB2000E the same as the other controllers, except has the MPPT technology?
    It’s certainly similar. Other features include two-stage charging (Bulk and Absorb) plus EQ, and temperature compensation via an optional remote battery temp sensor. For AGM batteries, the EQ function is essentially useless.

    The Morningstar SunSaver-20 is a 20 A, two-stage PWM (non-MPPT) controller with a local temp sensor, which is fine if the controller is located in the same general environment as the battery(ies).
    If I wired the two 65 watt panels in series, would this give the MPPT more voltage to convert to amps?
    Do not do this with your particular system. First of all, wiring the two modules in series may add their voltage, but their current is not added, and, when accounting for conversion losses, the net result would be less power. Also, the series voltage of the two modules would exceed the 2000E’s input voltage spec (30 Voc), and you may well damage the controller. Some controllers (i.e., Outback MX-60, large Blue Sky models) have a DC-DC step-down capability in addition to MPPT, but the SB2000 does not.
    My interest in the MPPT charge controller, is to increase the charge to the AGM during overcast days, using the 130 watts of panels I have. My panel space is limited. For three days per week, I am camped forty feet from the bay of San Francisco. It is seldom above 80 degrees in summer, typically 40 to 60 degrees with frequent overcast in winter. I will be able to tilt the panels to the south, but would prefer to have them flat.

    I have experimented with one panel flat on the ground. With the MPPT turned off, is shows 3.6 amps. Turned on it is 4.2 amps. I did not time how long it would do the 4.2 amps. Later in the day, it was at 3.8. I elevated the panel about 6-inches, it went back to 4.1 amps. I really do not know what the gain would be in a day, but considering I only need about 25 to 30 amps a day, that little gain could worth while. However, it I loose it because the controller some how takes away, then obviously there is no gain.
    Since you already have the MPPT controller, stay with it and make the best of it. I doubt that it “takes away” (uses/loses more power than the MPPT function provides), especially considering the KC-65’s decent output voltage. Just makes sure to follow the controller’s instructions and get the MPPT function optimally calibrated.

    The Sun is relatively high this time of year, so you won’t see much gain from tilting the modules. However, the collective benefits of a small tilt are worthwhile, as the module will generate more power, will run cooler (=even more power), and rain will help clean the module rather than letting dirt and water pool on top of the module. The tilt benefit will be more noticeable in the Winter hen the Sun is relatively low and you may see your energy demands increase as the nights grow longer.
    When I purchased the controller, I was told I did not need the battery temperature monitor with the Lifeline AGM.

    What do the instruction that came with/on the battery say?

    An AGM battery is a beautiful thing to waste. AGM batteries are susceptible to thermal runaway, so remote battery temp sensors and a temperature-compensating controller are generally considered a must, particularly in hot environments. In a cool- or cold environment, the BTS helps provide the higher charge voltage required. So, assuming your battery compartment doesn’t exceed 80 F, you may be able to get away with no BTS in the Summer, but the battery will be undercharged in the cool Winter, and that will lead to reduced capacity and shortened life.
    Actually, I am at San Quentin State Prison, in the parking lot.

    Here’s a link to insolation data for San Francisco.

    HTH,
    Jim / crewzer
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: New to solar, installing on RV

    The EQ function performs two tasks. One task is to make sure that all of the individual 2 volt cells in a series string are all fully charged. Since every cell in a battery will match exactly, over time some cells will fully charge and other will not--the Equalize function will "overcharge" some cells (with slightly smaller capacity) and fully charge the other cells (in lead acid chemistry, as I understand it, you need to fully charge a cell in order to prevent early life failure).

    The other function the EQ does, is once the cells are fully charge, they start to electrolyze the water into hydrogen (and oxygen) gas. The bubbles going up the sides of the plates helps circulate the acid and keep the sulfuric acid and the water well mixed (prevents stratification of heavy acid and the lighter water). With AGM batteries, there is no free liquid acid sloshing around--it is all contained in a mat so EQ does not help an AGM battery mix. And for AGM's, one comment I saw only recommended EQ'ing them a couple times a month.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2
    System2 Posts: 6,290 admin
    Re: New to solar, installing on RV

    Bill,

    Do you have any comments or thoughts on Jim's post?

    I appreciate different points of view and thoughts.

    One of the reasons I went with the AGM was to reduce the maintenance. It is my understanding that Equalizing the AGM is seldom required, if ever.


    Wayne
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: New to solar, installing on RV

    Jim is the expert on this stuff... I am just a user of Grid-Tied Solar (plus I am a systems design engineer in the real world).

    Everything that Jim said, I agree with. We, more or less, said the same things in slightly differing language.

    I posted the link to the index of the Solar Radiation information, Jim posted the text format of the data. Here is a PDF File link to California (scroll down for SF). May be a bit easier to read/understand the PDF version the first time through.

    http://rredc.nrel.gov/solar/pubs/redbook/PDFs/CA.PDF

    In general, rechargeable batteries are the most fragile / shortest life / most limiting part of any of these solar power systems. You made a great purchase with the AGM. The temperature sensor is just a good way to get the most and protect your investment.

    I think that they want about $25 or so for the temperature sensor (IIRC)--it is really your decision to purchase or not. If money is tight, probably not worth it. If you really need every bit of performance/life from the battery--it is probably worth it.

    Regarding AGM--How often to EQ was just some stuff I read somewhere--Just from battery construction in general, I would believe that EQ would help for AGM--but again, just a couple times per month at most. Most lead acid storage batteries last longer if they are fully charged than kept partially charged. And you need to overcharge a series connected multi-cell battery once in awhile to make sure that each of the series cells is fully charged. The problem is that with AGM's you don't really know what is happening inside until they fail--you are kind of blindly following factory recommendations on the assumption that they know best.

    Usually, the best place to go is to the vendor's web site and read what they recommend. Every vendor has slightly different recommendations--and sometimes, the vendors seem to conflict with each other (usually on minor points).

    I will differ to Jim (and others) to their exact recommendations for charging an AGM and to EQ or not.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: New to solar, installing on RV
    I purchased the panels and controller from NAWS. Nice guy in sales, but it would appear he doesn't know much more about this than I do.
    He ask the owner if I needed the battery temp sensor, and the answere was no. My AGM is inside with me and the controller, so it is at the same temperature as I am, maybe a little cooler due to it being closer to the floor.

    You say I should get the battery temp sensor. With my setup, is it to protect the AGM, increase the efficiency of the charger/battery or both?

    My recommendation for using the remote BTS is to protect the AGM battery and prolong its useful life.
    What is the "EQ function"? I have read and reread, and I am missing it.

    Bill’s write up on EQ is pretty good. However, AGM batteries are usually not equalized, especially if they’re properly maintained. My advice on EQ’ing an AGM battery is to only do it in strict accordance with the manufacturer’s specific instructions.
    The controller has a switch that turns the MPPT feature on or off. If there is a difference in amp output (MPPT on or off), it can be seen in the amp display. I do not think I would need the MPPT feature (if it works) in the summer months. Should I turn it off in the summer months?

    I’d leave it on all the time.
    It is extreamly rare for me to bring the AGM below 12.2 volts, usally two days in the winter. If I use 25 amps per day (from a 100 amp AGM), it appears to me that the 7 amp panels would produce an excess of 30 amps per day in the summer months. It is my understanding it is designed not to over charge the battery. Do I understand this correctly?

    Yes. Properly adjusted, the controller should not overcharge your battery. Follow Concorde’s instructions for your Lifeline AGM battery.
    The charge voltage is factory set at 14.0 volts. I am considering lowering it to 13.8 volts. It is my understanding that the AGM will handle the 14.0 volts or 13.8 just fine. I would think the 13.8 would give just a little more voltage for the MPPT and a little more safety margin for the AGM. What is your thought on this?

    I think 13.8 V ~ 14.0 V at 77 degrees F is too low for your battery. The result will be an undercharged battery that will not provide optimal daily service or long life. Concorde says to use 14.2 V ~ 14.4 V. FWIW, my charger is set at 14.35 V ref 77 F (measured at the battery terminals near the end of the Absorption stage).

    Finally, while I do know a bit about some of this stuff, I don't know everything about all of this stuff. Objective discussion and debate is healthy and encouraged! :wink:

    HTH,
    Jim / crewzer
  • System2
    System2 Posts: 6,290 admin
    Re: New to solar, installing on RV

    I really appreciate you guy's time on this. You have helped understand quite a lot. I still have a lot to learn, but can only absorb so much at a time.

    I will revisit the Lifeline information. I do plug into shore power on weekends. My WFCO charger/converter appears to be doing it's job. It will bring the 100 AMP AGM up to 13.2 volts with .2 to .3 amps, which I understand to be the sleep mode. I have tried several methods to eliminate the surface charge, and always end up with 12.9 to 13 volts at the battery.

    I would like to say cost is no object on this stuff, but it is not true. As you can see, I did not go as cheap as I could have. I will follow your advise and get the temperature sensor.

    I appreciate the same response stated in a different way. It really helps the learning curve. You really have it when both explanations are clear to you.

    If you think of anything else, please let me know. Mean while, I will study what I have, and come up with more questions.


    Wayne
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: New to solar, installing on RV

    i will also say the battery temperature sensor is almost a necessity for those agms. concorde agms are voltage critical and that changes with the temperature. you must stay within the voltage specified for whatever temperature it may be at that time. these batteries can take an amp for an amp in recharging, but don't go outside of the voltage tolerance and this was told to me by concorde.
    as to eqing these follow their recommendations, but it would be a very rare thing possibly years down the road for a bank of batteries, rather than one battery that may not need it at all. if so this would be an abused battery that would allow fluctuations within the cells of the battery to happen so i can't rule out 1 battery needing it at some time. with proper recharging and not allowing severe discharges over about 60% for this battery and no long time intervals between full charges i'll go out on a limb and say that you'll probably never need to eq this 1 battery.
  • Patman3
    Patman3 Solar Expert Posts: 62 ✭✭✭✭
    Re: New to solar, installing on RV
    Wayne wrote:

    The controller has a switch that turns the MPPT feature on or off. If there is a difference in amp output (MPPT on or off), it can be seen in the amp display. I do not think I would need the MPPT feature (if it works) in the summer months. Should I turn it off in the summer months?

    Thanks again for the input.


    Wayne

    Wayne, I have a BS2000E. That switch does NOT turn off the MPPT, it only changes the DISPLAY so you can show actual amps from panel or boosted chargeing amps (MPPT), or the first postion, battery voltage. It always does MPPT when it can and a little red LED on the backside will light if it is doing MPPT. there is screwdriver setting to set the MPPT voltage, usually Voc-Vmp, around 4.4, mine is 4.1V. Hope this helps and you stay on the outside of those bars.
  • System2
    System2 Posts: 6,290 admin
    Re: New to solar, installing on RV

    niel - As I previously stated, I will add the battery temperature sensor to my system. After spending about $1200 for the system, what is another $25?

    Your post on one AGM battery, as it pertains to EQ, reinforces my understanding, thanks.



    Patman3 - I appreciate the correction. I was aware that the little red LED on the backside will light if it is doing MPPT. It did not occur to me to look at the led, after moving the switch. It is tough enough to understand this stuff, without being smart enough to look at a led. :oops: I wonder what all those red lights are on the dash of my truck? :roll:

    Do you have AGM batteries?

    Please post anything you thing is worth knowing for a complete novice, especially the BS2000E. Do you think it is good, bad or indifferent? Would you do it again? How many watts are your panels? Do you tilt your panels? Do not assume I know anything, unfortunately I know very little on this subject.


    Wayne
  • Patman3
    Patman3 Solar Expert Posts: 62 ✭✭✭✭
    Re: New to solar, installing on RV
    Reddog1 wrote:

    Do you have AGM batteries?

    Please post anything you thing is worth knowing for a complete novice, especially the BS2000E. Do you think it is good, bad or indifferent? Would you do it again? How many watts are your panels? Do you tilt your panels? Do not assume I know anything, unfortunately I know very little on this subject.


    Wayne

    LOL on the LED!  I have absorbed glass mat batteries (AGM) just because they are maintance free and can be sent via UPS.  http://store.solar-electric.com/pvx-1295.html  I used to use deep cycle marine trolling batteries, they suck.
    I like the Blue Sky 2000E as a starter controller, although it's more for RV's.  You can add more in parallel if you go over 25 amps, or just go the right way and get an Outback MX-60 when you go bigtime.
    Yes I would get another 2000E, in fact I have two, one at each of my homes.
    My panels are Mitsubishi 110W http://www.discountpv.com/solarpanels/PV-MF110EC3.htm I have 4, although I really like these http://store.solar-electric.com/kc-120.html
    My roof is sloped at about 30 degrees due south, so I am lucky there, I just mounted them about 1 inch off the roof, flat.  Tilt is very important in the winter, you want to tilt them up 45-60 degrees or Latitude+23.5 degrees.  Summer should be flatter, lat-23 and then the sun won't shine on the back of them and you have a longer day exposed.
    I seldom use that little recessed blue push button (Equalize). It raises the voltage to over 14.7V and I don't want to cook the battery. If I do push it , its during the afternoon when batteries are fully charged and I'm trying to pump a little more power in, and I only do that for 1 hour at most.
  • System2
    System2 Posts: 6,290 admin
    Re: New to solar, installing on RV

    I do infact have a RV. Actually a 11.5 foot slide in camper. My roof free space is limited, therefore I must use care as to where I mount my panel/s. I now have two 65 Watt panels, as previously stated. I think the most I could add would have to go in a space about 30"x96", but I doubt I will.

    I have avoided the following question so I would not reveal just how ignorant I am on this subject, but when you say "tilt them up 45-60 degrees", do you mean from a horizontal position, raise the panel up 45-60 degrees from the horizontal position?

    What brand of absorbed glass mat batteries (AGM) are you using? EDIT: I see in your signature that you have Concorde AGMs. Guess I will have to put that beside the LED. :-D


    I find your post very informative, as I am sure others have, just judging by the 300 plus views. It would be great if those viewing would chime in, with questions or experiences.

    Thanks again.


    Wayne
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: New to solar, installing on RV

    wayne,
    your lifelines will have their warranty voided using them for solar just so you know.
    as to the tilt angle, yes, from the horizontal. if flat on the ground it would be 0 degrees. now i am at 40 degrees north latitude so that means that at the beginning of spring and fall if my pvs are angled at 40 degrees and on course aimed south they would be right on the money at solar noon. now when it is the beginning of summer it would be 40-23.5 or 16.5 degrees. now in the beginning of winter it is 40+23.5 or 63.5 degrees and is more vertical. it is more difficult when dealing with an rv roof as you'd probably feel better if it were anchored flat when moving and then raise it when parked. if it is possible you could remotely mount them so as to stay in the shade with the rv. this may make adjusting the angles easier with a ground mount, but more care to be sure nobody steals it.
  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: New to solar, installing on RV
    Tilt is very important in the winter, you want to tilt them up 45-60 degrees or Latitude+23.5 degrees.  Summer should be flatter, lat-23
    now when it is the beginning of summer it would be 40-23.5 or 16.5 degrees. now in the beginning of winter it is 40+23.5 or 63.5 degrees and is more vertical.

    For a reference tilt angle = latitude, increasing PV array tilt in the Fall and Winter, within limits, can lead to improved Winter energy production. Similarly, decreasing tilt angle in the Spring and Summer helps as well.

    However, I submit that increasing an array’s tilt angle by +/- 23.5 degrees is too much and therefore is a less than optimal adjustment.

    A Fall and Winter tilt adjustment of +23.5 degrees will result in optimal solar noon alignment on just one day: December 21. There will be a tilt (declination) error on all other days, with a maximum of 23 .5 degrees. Similarly, A Spring and Summer tilt adjustment of -23.5 degrees will result in optimal solar noon alignment on just one day: June 21. There will be a tilt (declination) error on all other days, with a maximum of 23 .5 degrees.

    In general, a compromise seasonal adjustment of +/- 15 degrees works better. Solar noon alignment will be correct on two days in each six month cycle, and the maximum error will be just 15 degrees. As a result, the array will be able to produce more total seasonal energy than if using the +/- 23.5 degree adjustments.

    The National Renewable Energy Laboratory (NREL) included +/- 15 degree offsets for their 30-year solar radiation data collection used to create their Solar Radiation Data Manual. You can also model the differences between the +/- 23.5 degree and the +/- 15 degree solutions using the PV Watts calculator.

    HTH,
    Jim / crewzer
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: New to solar, installing on RV

    just for the record i do agree with crewzer that it should be lower than the solar noon peak angle and because it would be a seasonnal adjustment crewzer's stated angles would be good. i think the winter angle could and should go farther than 15 degrees lower, but many mounts only move in 15 degree increments anyway.
  • Patman3
    Patman3 Solar Expert Posts: 62 ✭✭✭✭
    Re: New to solar, installing on RV

    Ya, I don't really tilt mine that much either, I just wanted to sound cool because the earths axis is tilted at 23.5 degrees, Crewzer is correct. To get a rebate from my power company (UniSource Arizona) the panels must be between 20 and 35 degrees year round, or at least there is no mention of changing for winter.
  • System2
    System2 Posts: 6,290 admin
    Re: New to solar, installing on RV
    niel wrote:
    wayne,
    your lifelines will have their warranty voided using them for solar just so you know.

    I read your post on this in another thread. I went to the http://www.lifelinebatteries.com/ web site, and the last paragraph is as follows:

    "In addition, we are original equipment on Monaco, Vantare, Marathon, Parliament, Country Coach and Royal motorcoaches and recreational vehicles where inverters such as Heart, Trace, Xantrex, and Magnum apply heavy loads to batteries. Our Batteries efficient charge acceptance and low internal discharge make them ideal for photovoltaic (solar) and UPS applications where sealed batteries are desired."

    I do not know why using the "...lifelines will have their warranty voided using them for solar...". I, and I would think others, would really appreciate knowing where this voided warranty issue came from. I do not think this should be treated lightly, I am aware of several RVers that have been sold Lifelines buy venders, knowing they would be used with solar.



    On the tilt, I hope to mount my panels today. The tilting bracketing has become a challenge due to the shape of my roof, so I have decided to mount non-adjustable for now. I am saving the tilt info you guys are giving me, so I can use it later.


    Wayne
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: New to solar, installing on RV

    they had told me they have batteries made for the solar applications and are the sun xtenders. if you wish to put them on the spot for it please do so, but don't blame the messenger for what he was told by them.
  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: New to solar, installing on RV

    And, just to muck this up a bit further, here's part of the warranty statement from Lifeline's website:

    Battery Warranty:

    Lifeline batteries have a 5 year pro-rated warranty with a 1 year free replacement period when installed in Marine or RV applications. Applications other than Marine or RV, Lifeline batteries are pro-rated for 1 year.


    If this is what's in writing, then it would seem to me that this would trump the verbal statement deliver to niel. Either way, the corn-fusion form Concorde can't be helpful to their customer base.

    Regards,
    Jim / crewzer
  • System2
    System2 Posts: 6,290 admin
    Re: New to solar, installing on RV

    niel - I apologize if my post sounded like I was hanging the messenger. That was not my intent. The person representing Lifeline should be willing to show you and I, in writing, support for their comment. I submit to you, in every trade I have worked in, I have encountered coworkers that really did not have a clue. My concern is that to repeat something as serious as this, without a specific source, makes the data suspect.

    crewzer - Lets muck it up more. In my application, I am using my Lifeline in a RV, so thats means it has the warranty you cited. But wait, I have solar on the RV, so the warranty is void, as per a verbal statement from an unknown Lifeline employee? Which applies, the RV application or the solar.


    The Lifeline site clearly states they are ideal for photovoltaic (solar). See my previous post.

    The http://store.solar-electric.com/cosuagmba.html site says:

    "SunExtender vs LifeLine batteries: Both are made by Concorde and are very similar in basic construction and technology. They carry a different warranty, and there are some slight differences internally. The LifeLine also usually have the SAE or dual type marine terminals instead of the bolt only terminals that most of the SunExtenders have. To a large extent in many applications, they are interchangable. You will NOT get the 5-year LifeLine warranty if you use SunExtender batteries in marine or RV applications, but the in general the SunExtender batteries are cheaper because you are not paying for that warranty."

    This suggest to me, the SunExtenders will not hold up to the riggers of marine or RV use. Great for it's intended application, stationary applications. Although not clearly stated, the Lifeline is for marine and/or RV applications (per Lifeline web site), with or without solar (excellent for solar, per Lifeline web site) .


    Again I apologize if I appeared to "blame the messenger" for bad and possibly erroneous news. That is not my intent. There are a lot of views of this thread. Maybe someone will chime in with some actual experience on this subject.


    Wayne