RV 400 to 450 watt PV configuration questions

ScoCan

Uncertain if this fits into advanced, basic, or crazy - but here goes.

I'm looking to install a PV system on our small (24 ft) RV.
Starting panel config:
3 x 150 or
4 x 100
Using semi flexible panels likely mounted to aluminum backing for heat transfer and ability to tilt/move.

Would like to use distributed mppt (one per panel) or an mppt with multiple in.
This is both for shade tolerance and ability to move panels around campsite a bit
If distributed, looking for networked controllers to maximize battery charging and usable power.

Will be starting with fla but likely moving to LiFePO4 in future, so need a programable system.
Will likely have to use genset to assist as we use a fair amount of power. Thus a controller that can priority combine would be helpful.

We have the panels and initial batteries selected, would greatly appreciate controller, networking, monitoring advice.

Thanks, ScoCan

Cariboocoot

Re: RV 400 to 450 watt PV configuration questions

Welcome to the forum.

Well we don't have a section for "I want to spend huge amounts of money for a very tiny advantage".

Your proposed array size is 400 to 450 Watts. Normally that would be all on one small controller. An MPPT type controller is $300 and up. You want one per panel? Might as well spend the money on more panel and let the system run at a lower efficiency rate. Cheaper and easier to do.

Beware the specifications on flexible panels too; they can have some difficult-to-deal-with Voltages. They can also have some pretty low efficiency rates. You would probably be better off filling the available space with monocrystaline panels and accepting the losses from imperfect angles. If you need moveable panels, just have them separate.

ScoCan

Re: RV 400 to 450 watt PV configuration questions

Hi Cariboocoot,

Thanks for the welcome.

I am looking at the smaller MPPT controllers - Such as the Genasun GV series (Specifically the GV-10).

Do need to ascertain if they can be reprogrammed for Lithium if we start with a purchase of the LA version (they make one for each and I'm guessing only the PIC/program is different). And how well they cooperate when used in parallel. -- I will call and ask.

They run about 140.00 each (USD).

Alternate options (from a quick google search) can be found here.

The PV panels are made with Sunpower cells and are pretty good on efficiency, excellent on weight (which is critical for center of mass and GVWR/CCC)

With a 24' RV that already has stuff on the roof, we are limited in PV real estate; hence the desire to be efficient and hopefully able to augment with extra panels off the roof when parked.

I'm curious about hands on experience with other small MPPT controllers for off grid use.
Are there small MPPT controllers that are networked for better cooperation and ideally monitoring?
Are there small MPPT controllers that can be reprogrammed for different battery chemistry?
Is there an appropriate centralized MPPT controller (PV Wmax likely <1kw) that has multiple panel inputs and can optimize for shading?
I'd love advise and ideas from anyone who has done something similar.

Thanks!

Chris

Re: RV 400 to 450 watt PV configuration questions

Have you looked into the MidNite "Kid" Mppt controller? I have 4 X 100 watt panels mounted on the roof of our RV with great results.

Cariboocoot

Re: RV 400 to 450 watt PV configuration questions

I'm not sure anyone here has used a Genasun controller yet, but the Victron equipment is well-liked (mostly overseas installs).

Keep in mind that the performance improvement for MPPT is only about 10% over PWM, so spending even $140 each on four controllers vs. one ... You can buy a fair amount of panel for $420.

You can parallel two MidNite Kid 30 Amp MPPT controllers to act as one, but that's rather more than you need. Although it would be possible to put such complexity in a small 15 Amp controller there's not much point in doing it; the added expense would not be justified by increased performance.

Really if you just parallel the four identical panels on one controller you won't have any problem. Notice I said parallel; if one panel is shaded out you lose only the current contribution from that panel. And with identical panels the Voltage will be the same so there is no trouble with a higher Voltage panel pulling a low one above its Vmp point.

As far as panel efficiency goes those cells claiming 24% would be tops. If it is real. Has anyone here used these? I don't know. Some have the HIT panels with around 20% efficiency so it just may be possible. Keep in mind that with less-than-perfect insolation the high efficiency panels do not offer a large improvement and may even fair worse because their harvest depends on direct sun (i.e. the drop-off in output with sun angle change is more drastic).

Different battery chemistry does require some changes to Voltage and time settings. Certainly the higher-end controllers can do this. Smaller ones ... check very carefully before you buy.

SolarPowered

Re: RV 400 to 450 watt PV configuration questions

ScoCan wrote: »

The PV panels are made with Sunpower cells and are pretty good on efficiency, excellent on weight (which is critical for center of mass and GVWR/CCC)

Stay away from those panels, they are not authorized from sunpower, and the name is being used illegally.
There are a couple funny things going on in the market place.
1) sunpower distributes whats called the grade B cell it depreciates at over 1% or greater annualized that's why sunpower doesn't use the cells. There are also "other" deficient issues, such as operating conditions don't meet the STC requirements, which means under higher tempratures these cells suffer dramatic voltage issues. Sunpower sells the cells to the chinese, australians, and europeans. Sunpower is an american company so the company wants to keep those cells out of the US domestic market, they have been selling the grade B's in other markets for some time, but now they are showing up every where on ebay, etc......

2) the chinese have been trying to replicate those cells such as TOPOINT which is now the largest supplier of chinese cells in the world. The chinese steal US patents and I don't condone the purchase of the "FAKE" sunpower badged products.

3) It's guaranteed to be an inferior product, its not a true sunpower product, not backed by sunpower, and does not go through the testing practices and conditions, that grade A maxeon, E17,E18, E19, E20 cells and manufactured panels go through. If you buy those panels you have spent way to much because grade B's on the open market go for around .40~.50 cents per watt.

SolarPowered

Re: RV 400 to 450 watt PV configuration questions

Just to add to my point here are some picks from the "sunpower" chinese models. As you can see the back contact cell has been cut into 3 sections.

1) to lower the intital impacts of resistance that effect the cells efficiency.
2) grade B can be any cell that didn't meet the production requirement, meaning broken as it was cut from the ingot and or production, or the chemistry of gasses and or AR coating did not apply correctly to the cell..
3) teh cut cells are then again cell sorted "to come close to the standard", but it is not infact the "SUNPOWER" standard for cells .

While chinese advertising is claiming 24% efficient. For the record sunpower has only made a marketable 22.7% efficient cell, on the cell level before glass is applied which drops the efficiency to 20%. MAXEON cell technology which reaches roughly 23.2% apparently cannot be cut because of the mechanical characteristics of how the maxeon cell operates, and how it is treated. Which means all the cells advertised from china are realistically under 19% conversion efficient at best, something tells me the numbers are much worse than what is actually advertised.

The only chinese based "panel" non folding from renogy again claims 24% efficiency has uncut cells.
Attachment not found.Attachment not found.

ScoCan

Re: RV 400 to 450 watt PV configuration questions

Thanks all for the comments and assistance, still working on the project but getting closer.

Had a very nice chat with Ryan at MidniteSolar and the kid is likely the one we will go with - Thanks Chris and Coot.

Stay away from those panels, they are not authorized from sunpower, and the name is being used illegally. .... The only chinese based "panel" non folding from renogy again claims 24% efficiency has uncut cells.

I hadn't actually listed the specific panels. That said, there are certainly some legit providers. Both Solbian and Renogy come to mind.

The datasheet on Renogy's 100W Panel lists cell efficiency at 19.9%. Per their tech support chat, they are using 'Grade "A"' cells. I'm willing to believe them until proven otherwise - given they are in Chino, CA and well within US litigation reach.

Attachment not found.

--
Datasheet re-compressed to comply with forum attachment values - no data was intentionally changed.

SolarPowered

Re: RV 400 to 450 watt PV configuration questions

ScoCan wrote: »

The datasheet on Renogy's 100W Panel lists cell efficiency at 19.9%. Per their tech support chat, they are using 'Grade "A"' cells. I'm willing to believe them until proven otherwise - given they are in Chino, CA and well within US litigation reach.

Just read that data sheet, some where there is some arbitrary information it only comes with a 5 year craftsmanship warranty, and no tier 1, 25 year performance warranty.
Give it a wack though and let us know what the results are.

BrokerDon

Re: RV 400 to 450 watt PV configuration questions

We installed a Renogy 250W monocrystalline panel with a Renogy Tracer 40A MPPT charge controller on our 24 foot Winnebago View and its working great. The panel is sending 34.7V to the controller which recharges our dual 6V Sam's Club Energizer GC2 Premium batteries (232A 12V bank) at up to 11A at 14.2V bulk charge before dropping to 13.2V maintenance charge. Installing ONE panel saved a lot of time & money since no combiner box is required and only ONE set of solar panel mounts is needed... and the $238 price for the 250W Renogy panel was cheaper per watt then buying individual 100W panels.

You can see our installation photos here: https://groups.yahoo.com/neo/groups/View-NavionTech/photos/albums/1856159274

westbranch

Re: RV 400 to 450 watt PV configuration questions

Broker, you would do well to add another panel so that your amps delivered to the batteries is closer to the 10% target (~22A) needed for a full charge and save you from having a bank slowly dying on you prematurely

BrokerDon

Re: RV 400 to 450 watt PV configuration questions

We used a $210 Renogy Tracer 40A MPPT charge controller and a $40 Renogy MT-5 Tracer Meter for MPPT Charge Controller with our $238Renogy 250W 32V monocrystalline panel. Our total system cost including AWG 8 from the panel to the charge controller, AWG 4 from the charge controller to our batteries, a Big Baby Box, (2) 12V DC breakers (on input & output of charge controller), wire wrap, LiquidTite flex conduit, elbow and connectors was $700. We bought the latter items from No. AZ Wind & Sun (NAW&S)... and would have bought the panels & controller here too but Renogy was local and I didn't find NAW&S until I discovered fuses weren't the way to go to isolate our charge controller. NAW&S's experts got me the RIGHT parts and told me how to install them. AWESOME!

If you wanted to cut this cost significantly you could substitute cheaper charge controllers. Going to a 20A MPPT controller would save $70... and down to a 20A PWM controller would save $180. I went with the more expensive 40A MPPT controller so I could install higher wattage panel in the future without having to upgrade charge controllers... and our 40A MPPT controller runs super cool, even on the hottest sunny SoCal desert days.

BrokerDon

Re: RV 400 to 450 watt PV configuration questions

westbranch wrote: »

Broker, you would do well to add another panel so that your amps delivered to the batteries is closer to the 10% target (~22A) needed for a full charge and save you from having a bank slowly dying on you prematurely

Agreed. In a perfect world we'd add another panel but unfortunately the roof on our 24 foot RV is seriously cluttered with an AC unit, 2 Fan-Tastic vent fans, refrigerator vent, HDTV antenna, Sirius satellite antenna, FM antenna, roof ladder brackets, shower skylight, and a myriad of vents which really only leaves room for one large panel or 3 smaller 100W panels. Multiple panels would have been a lot more work, expense, aerodynamic drag, and looked tacky (our panel can barely be seen behind the Winnebago "winglets"). Pictures here: https://groups.yahoo.com/neo/groups/View-NavionTech/photos/albums/1856159274

I spent hours using a C.A.D. program trying to figure out a way to install a 2nd panel and concluded one large panel was our best option... Which is why I'd love to find a panel > 325W that fits into the 41"x62" space the SunPower 327W E-series or 335 / 345 X21-series panels fit. A 41"x72" panel I could actually fit but that would eliminate the narrow footpath we use to get to the front of our RV's roof for washing the cabover area and transparent smoke vent lid.

Definitely tradeoffs... which hopefully a 325W or larger panel would minimize.

What 325W+ panels would you recommend for these footprints?

• 41"x65"
• 42"x72"

:cool:

westbranch

Re: RV 400 to 450 watt PV configuration questions

Sorry, not up on what GT panels are out there.
Alternatively, what do you have for a gen set to do a bulk charge in the morning and let the PV do the absorb and Float phases.. This can be used to ensure battery health longer term.

Cariboocoot

Re: RV 400 to 450 watt PV configuration questions

Just a mention here.

A 300+ Watt panel isn't any more efficient than a smaller one, it's just a larger panel. Watts per square area varies little because the panels are all made the same and have the same relative efficiency. Only small gains are made in package containment.

Quite often it makes more sense, especially in an RV application, to use multiple smaller panels. The reason for this is that they are easier to manage and don't stress as much for having more secure mounting, and can tolerate partial shade when in parallel (instead of having the whole Wattage of one panel knocked out at once). They are also often cheaper per Watt than the latest high power panels.

A KD320GX measures 65.5" x 52" - it's not going to fit in a 42" wide space. About 10.6 sq. inches per Watt.

A SolarWorld 315 measures 78" x 39" - it will fit in 42" but not 72" length restriction. About 9.6 sq. inches per Watt: smaller panel, yet more power per area.

Drop down to a SolarWorld 280 and it measures 66" x 39" - will fit in 42 x 72 space. About 9.1 sq. inches per Watt. And less money per Watt than the KD320.

To get something to fit in the 65" length limit you'd be down to A KD220 Watt panel: 59" x 39". About 10.4 sq. inches per Watt. Also less expensive than the KD320.

The assumption that a higher Watt panel is a better choice is not true.

BB.

Re: RV 400 to 450 watt PV configuration questions

Your best bet for finding one or two off panels--Call around to local and other distributors/retailers. Many times, they will not list remainders on their websites.

As an example from our host for large format multi/poly crystalline panels. 320 Watt from Kyocera:

http://www.solar-electric.com/kyocera-kd320gx-lfb-320-watt-polycrystalline-solar-panel.html/

The Kyocera KD320-LFB contains 80 cells mounted in a black anodized frame. This is currently the largest solar panel made by Kyocera. Kyocera's solar modules are the first in the world to have been certified in the Long-Term Sequential Test that measures a module's durability and reliability. The new test was carried out by TUV Rheinland, a third-party organization that certifies the safety and quality of a wide range of products. The Kyocera KD320 solar panels are mainly intended for grid-tie systems. They may be installed for battery charging systems if used with the Outback Power, Midnite Solar, Schneider Electric MPPT, Morningstar MPPT, or other MPPT charge controller that can take higher input voltages and convert it down to the correct battery voltage. Maximum power rating: 40.1 volts at 7.99 amps.
Specifications:

• P_mp = 320 Watts
• V_mp = 40.1 Volts DC
• I_mp = 7.99 Amps DC
• V_oc = 49.5 Volts DC
• I_sc = 8.6 Amps DC
• P_tolerance = +5/-3%
• Weight = 60.6 lbs.
• Dimensions = 65.43" x 51.97" x 1.8"

A mono-crystalline panel may be better (if you can find one the right size and price) as they will give you a bit more power from the same foot print (more efficient solar conversion).

Are you going to mount flat to roof or make some sort of tilting framework?

-Bill

BrokerDon

Re: RV 400 to 450 watt PV configuration questions

Cariboocoot wrote: »

Just a mention here.

A 300+ Watt panel isn't any more efficient than a smaller one, it's just a larger panel. Watts per square area varies little because the panels are all made the same and have the same relative efficiency. Only small gains are made in package containment.

Quite often it makes more sense, especially in an RV application, to use multiple smaller panels. The reason for this is that they are easier to manage and don't stress as much for having more secure mounting, and can tolerate partial shade when in parallel (instead of having the whole Wattage of one panel knocked out at once). They are also often cheaper per Watt than the latest high power panels.

A KD320GX measures 65.5" x 52" - it's not going to fit in a 42" wide space. About 10.6 sq. inches per Watt.

A SolarWorld 315 measures 78" x 39" - it will fit in 42" but not 72" length restriction. About 9.6 sq. inches per Watt: smaller panel, yet more power per area.

Drop down to a SolarWorld 280 and it measures 66" x 39" - will fit in 42 x 72 space. About 9.1 sq. inches per Watt. And less money per Watt than the KD320.

To get something to fit in the 65" length limit you'd be down to A KD220 Watt panel: 59" x 39". About 10.4 sq. inches per Watt. Also less expensive than the KD320.

The assumption that a higher Watt panel is a better choice is not true.

Great recommendations! Thanks!

Looks like our Renogy 250 mono panel is the best option for now, especially at $238. The only other panel that fits our uncluttered roof area would be a SunPower 327W E-series or 335 / 345 X21-series panel (They're only 41" x 62")... but SunPower dealers say they can't just sell me a panel... I'd need to buy an entire system and they don't sell & install off-grid systems this small. CATCH-22

The good news is panel efficiency seems to be increasing... and the 40A Renogy Tracer MPPT controller, 8 AWG solar panel and 4 AWG battery bank wires we installed can easily handle a higher wattage panel that fits in the future.

BrokerDon

Re: RV 400 to 450 watt PV configuration questions

BB. wrote: »

Your best bet for finding one or two off panels--Call around to local and other distributors/retailers. Many times, they will not list remainders on their websites.

As an example from our host for large format multi/poly crystalline panels. 320 Watt from Kyocera:

http://www.solar-electric.com/kyocera-kd320gx-lfb-320-watt-polycrystalline-solar-panel.html/



A mono-crystalline panel may be better (if you can find one the right size and price) as they will give you a bit more power from the same foot print (more efficient solar conversion).

Are you going to mount flat to roof or make some sort of tilting framework?

-Bill

Currently we're using a 250W 36V Renogy mono-crystalline panel and getting excellent results: 34.7V from the panel converting to 11A at 14.2V in bulk mode... Plenty for our RV's miserly DC power consumption since our refrigerator and catalytic heater both run off LP and all our lights are LEDs. DC power is mostly used for recharging our iPhones, iPad, GPS and MacBook laptops. We only use our 3.2kW Onan diesel generator infrequently when we run the AC or use the microwave.

We mounted the panel on homemade brackets made from aluminum angle stock... which will enable us to tilt them on one axis if necessary... and possibly another axis with a 90º adaptor.

BrokerDon

Re: RV 400 to 450 watt PV configuration questions

SolarPowered wrote: »

Just read that data sheet, some where there is some arbitrary information it only comes with a 5 year craftsmanship warranty, and no tier 1, 25 year performance warranty.
Give it a wack though and let us know what the results are.

Warranty Information on our 250W panel from Renogy's website:

• 25-year transferable power output warranty: 5-year/95% efficiency rate, 10- year/90% efficiency rate, 25-year/80% efficiency rate
• 10-year material and workmanship warranty

http://www.renogy-store.com/250W-Mono-p/rng-250d-bk.htm

Renogy is near us and has been great to work with. Even took back a set of MC4 cables we didn't use in our installation with no restocking fee... and allowed us to buy one 250W panel even though their website said they only come in sets of two. They also send out discount coupons if you're on their email list.

SolarPowered

Re: RV 400 to 450 watt PV configuration questions

BrokerDon wrote: »

Great recommendations! Thanks!

Looks like our Renogy 250 mono panel is the best option for now, especially at $238. The only other panel that fits our uncluttered roof area would be a SunPower 327W E-series or 335 / 345 X21-series panel (They're only 41" x 62")... but SunPower dealers say they can't just sell me a panel... I'd need to buy an entire system and they don't sell & install off-grid systems this small. CATCH-22

The good news is panel efficiency seems to be increasing... and the 40A Renogy Tracer MPPT controller, 8 AWG solar panel and 4 AWG battery bank wires we installed can easily handle a higher wattage panel that fits in the future.

Solar World SW275MONO silver/white is better for the price VS The RENOGY 250 Black on Black. Higher conversion, higher amps. Not on the level of sunpower power output/conversion, but if you pay attention to the 327 SPWR it has a negative and positive power tolerance. Solar World is a positive power tolerance panel of +5, the frame and glass are both better than the SPWR and the Renogy, that renogy spec you have has a +3 power tolerance, but will have a down fall of "black on black" I-V curve.

Also unless you live in cold climate conditions with snow, you aren't going to want a black on black panel. Summer time heat will kill voltage. Black on Black is great if the conditions stay within the STC operating temperature or lower.Black backing tends to have the power output plateau from reaching higher peaks, at higher tempratures, mostly because black as it should attracts heat, the cooler the operating condition the higher the the output peak.


SPWR by far has the best I-V curve response, Solar World follows second best in I-V curve response, Renogy follows last in I-V curve response.

I've been doing alot of comparisons with positive/ negative power tolerance panels VS Positive power tolerance panels, and most of the positive power tolerance panels exceed the name plate specs. (I.E) in the case of the SW275 mono siilver/whites, most are operating as if closer to what solar world use to offer as a SW280 silver/white. Solar world discontinued the SW280 because the level of cell sorting cost the company more money when the specs were better suited as a 275Wp. In most cases a 275 on average will operate with an I-V curve of that of a 277.5watt panel or better. A Renogy with a +3 tolerance will operate with an I-V curve 1 watt above letts say roughly 251Wp

BrokerDon

Re: RV 400 to 450 watt PV configuration questions

westbranch wrote: »

Sorry, not up on what GT panels are out there.
Alternatively, what do you have for a gen set to do a bulk charge in the morning and let the PV do the absorb and Float phases.. This can be used to ensure battery health longer term.

We have an 3.2kW Onan QuietDiesel genset connected to a Progressive Dynamics PD4655 55 amp 4-stage converter/charger. It works great but is NOISY and smelly... and uses the same fuel tank as our Winnebago View's Mercedes Bluetec 3.0 liter turbodiesel.

However, the new dual Sam's Club Energizer GC2 Premium 6V 232Ah batteries should handle the LEDs and electronics we run at night without running our inverter... Meeting our goal of eliminating running the genset usage altogether and keeping our View's MPGs normal.

westbranch

Re: RV 400 to 450 watt PV configuration questions

to ensure good service from your batteries you need to get a full charge about weekly... or they will start to sulphate... a slow but certain death. Controlling the usage is a good plan, so that you PV can replace your use . Too bad you cant add that next panel. Have you thought of a ground mount?

BrokerDon

Re: RV 400 to 450 watt PV configuration questions

SolarPowered wrote: »

Solar World SW275MONO silver/white is better for the price VS The RENOGY 250 Black on Black. Higher conversion, higher amps. Not on the level of sunpower power output/conversion, but if you pay attention to the 327 SPWR it has a negative and positive power tolerance. Solar World is a positive power tolerance panel of +5, the frame and glass are both better than the SPWR and the Renogy, that renogy spec you have has a +3 power tolerance, but will have a down fall of "black on black" I-V curve.

Also unless you live in cold climate conditions with snow, you aren't going to want a black on black panel. Summer time heat will kill voltage. Black on Black is great if the conditions stay within the STC operating temperature or lower.


SPWR by far has the best I-V curve response, Solar World follows second best in I-V curve response, Renogy follows last in I-V curve response.

I've been doing alot of comparisons with with positive/ negative power tolerance panels VS Positive power tolerance panels, and most of the positive power tolerance panels exceed the name plate specs. (I.E) in the case of the SW275 mono siilver/whites, most are operating as if closer to what solar world use to offer as a SW280 silver/white. Solar world discontinued the SW280 because the level of cell sorting cost the company more money when the specs were better suited as a 275Wp. In most cases a 275 on average will operate with an I-V curve of that of a 277.5watt panel or better. A Renogy with a +3 tolerance will operate with an I-V curve 1 watt above lets say roughly 251Wp

Great recommendation! I wish I had known that before I bought my Renogy 250W panel. So far our Renogy panel has been putting our 34.7V into our 40A Renogy Tracer MPPT controller which is providing 11.1A at 14.2V in bulk mode to our battery bank in 90ºF SoCal weather. How many amps in 14.2V bulk mode do you project the SW280 (they're still available to purchase) and SPWR 327 E-series would output under similar conditions?

BrokerDon

Re: RV 400 to 450 watt PV configuration questions

westbranch wrote: »

to ensure good service from your batteries you need to get a full charge about weekly... or they will start to sulphate... a slow but certain death. Controlling the usage is a good plan, so that you PV can replace your use . Too bad you cant add that next panel. Have you thought of a ground mount?

Our Renogy Tracer 40A MPPT controller switches from 14.2V bulk mode to 13.2V float mode and the Tracer MT-5 MeTer shows SoC bouncing between 98% and 100% fairly quickly (well within an hour) which I thought meant our batteries were getting a full charge.

Unfortunately a ground mount doesn't make sense since we usually move around a lot, including using our view for transportation during the day. Storing, deploying & connecting an additional panel, especially with our limited storage space, isn't an option unless we stay somewhere for a week which we've never done (we're too active and ADD / ADHD for that). The one option I've actually considered for a weeklong desert stay next year is mounting a 2nd panel the light bar of our Jeep Wrangler to add another 250W to our system to run a 3.0 to 4.6 amp TurboKool swamp cooler during the day. Currently our single 250W panel is providing 11 amps from our 40A Tracer MPPT controller so adding another panel isn't necessary... but would sure provide a larger safety cushion.

Cariboocoot

Re: RV 400 to 450 watt PV configuration questions

Have to point out that 14.2 Absorb ("Bulk") Voltage is a bit too low for flooded batteries.
If that charge controller can't be cranked up at least 0.2 Volts, get rid of it.

westbranch

Re: RV 400 to 450 watt PV configuration questions

here is the charging info for Trojan GC2's. This is a good general info document as well as specifics for Trojan, a must read... Note the section about 3/4 way down about Absorb at 14.8V etc

http://www.trojanbattery.com/tech-support/battery-maintenance/

SolarPowered

Re: RV 400 to 450 watt PV configuration questions

BrokerDon wrote: »

Great recommendation! I wish I had known that before I bought my Renogy 250W panel. So far our Renogy panel has been putting our 34.7V into our 40A Renogy Tracer MPPT controller which is providing 11.1A at 14.2V in bulk mode to our battery bank in 90ºF SoCal weather. How many amps in 14.2V bulk mode do you project the SW280 (they're still available to purchase) and SPWR 327 E-series would output under similar conditions?

Sorry I couldn't reply sooner I've been out of the country, and AT&T data usage is a PITA.
I hope the investment works wonders for you, I know teh Renogy product is a reasonable product I just wouldn't use the product on a GT scale, mostly a professional preference reason.

I can't help much on the specs for the SW280 panels. But what is still available of the SW280's is more expensive or whats left of the stock. I've been offered $1.10 per watt for the stock that is left of the SW280's, I buy the SW275's in bulk for under $.91 per watt.

However on the Gosolar california website it says the SW275 PTC performs at 247, while the SW280 performs at 247.3 so its really a moot point as far as its recognized from the operating characteristics.

SolarPowered

Re: RV 400 to 450 watt PV configuration questions

Cariboocoot wrote: »

Have to point out that 14.2 Absorb ("Bulk") Voltage is a bit too low for flooded batteries.
If that charge controller can't be cranked up at least 0.2 Volts, get rid of it.

The 14.2 absorb should have a tolerance of -/+ .5volts, its a pretty common spec for most chinese PWM and MPPT's, it's a redundant spec seen across the board on most chinese controllers on the market, to meet the "minimum" requirements for controller specification.

Since its a minimum spec it puts these "tracer" branded charge controllers in the realm of efficiency @ 80% some consumers have complained efficiencies meeting 75%, from what I have seen from the consumers that purchase them on ebay/amazon and leave comments on the comment boards. Its a TRACER MPPT its just rebadged by RENOGY.

BrokerDon

Re: RV 400 to 450 watt PV configuration questions

Cariboocoot wrote: »

Have to point out that 14.2 Absorb ("Bulk") Voltage is a bit too low for flooded batteries.
If that charge controller can't be cranked up at least 0.2 Volts, get rid of it.

Thanks for pointing that out! My error. Actually our 40A Renogy Tracer MPPT controller's 4-stages are at:

Equalization: 14.8V
Boost: 14.6V
Float: 13.8V
Boost Return: 13.2

http://renogy.com/wp-content/uploads/2014/05/MPPT-40A-Controller-Manual.jpg

BrokerDon

Re: RV 400 to 450 watt PV configuration questions

SolarPowered wrote: »

Sorry I couldn't reply sooner I've been out of the country, and AT&T data usage is a PITA.
I hope the investment works wonders for you, I know teh Renogy product is a reasonable product I just wouldn't use the product on a GT scale, mostly a professional preference reason.

I can't help much on the specs for the SW280 panels. But what is still available of the SW280's is more expensive or whats left of the stock. I've been offered $1.10 per watt for the stock that is left of the SW280's, I buy the SW275's in bulk for under $.91 per watt.

However on the Gosolar california website it says the SW275 PTC performs at 247, while the SW280 performs at 247.3 so its really a moot point as far as its recognized from the operating characteristics.

Thanks for the GoSolar website info. Great stuff!

Sorry to for the NEEBIE question but what does "GT scale" mean?

westbranch

Re: RV 400 to 450 watt PV configuration questions

GT is Grid Tied usually used to describe panels that are not rated in multiples of 12 v... 12, 24, 48, 96.... though the panels usually can be confused with true 12 or 24V panels as they do NOT have a Vmp that is high enough to charge an off grid battery ie 12 v panel will have a Vmp of ~ 17 volts, 24V needs ~ 35V Vmp