Planning Solar Panels

[evy]

Hi everyone,

I'm working on my very first DIY camper conversion, using a 2010 extended Ford E250.

I was looking at solar panels yesterday, I was going to make the move eventually but maybe sooner than I originally thought.

I just want to plan where the panels will be mounted on my roof rack and how many I needed, this is what I came up with.

I can fit a big 285W solar panel on the side of my van, with hinges on top and some sort of an adjustable bracket (see drawing)

I can also fit two smaller panels on the top of the roof rack but only in a specific area, I need space for my canoe or kayak on the right side and I can't put them too close to the rear which is the highest point of my van, as of now I have 2-3 inches of space when I back up through my garage door...

There probably is a 100W thin model I could install, around 20"x48" ish ?

Take a look at my roof rack drawing, I added the panels (clouds)

Also Is 485W of solar energy worth it? I don't know much about solar, I'll have two 6v golf cart batteries at 225AH.
My rig is fully equipped, 3 way fridge, microwave + convection, LED lights, pump, fans, AC + DC outlets...

I red that you can get more energy out of your panels by tilting them to face the sun.
Does anything exist on the market today to manually adjust the angle of a panel, I was thinking of adding a sturdy central bracket.

Thanks for any help! 🙂

[Chandalen]

I mistyped, I meant $500 for two @265w.

NABCEP is the industry standard certification for Photovoltaic (Solar) installers.

http://www.nabcep.org/

[KD4UPL]

Chandalen wrote:

smkettner wrote:
OK so $550 for 500 watts. With MPPT you could have 530 watts (2 panels) for $200 less.

What panels are that cheap? I did a quick search and I can find some Poly panels close to $500 @265w, but no Mono's.

I went for a larger controller, to allow for expansion.

Large panels in the neighborhood of 265w go for less than a dollar a watt normally. If you're paying $500 for a 265 watt panel you're getting ripped off x 2.

By the way, any 265 watt panel is going to be a 60 cell panel with a Vmp around 30 volts. This is going to need an MPPT controller regardless of price. Otherwise you'll only get about half the wattage out of the panel due to the vast voltage difference when hooked to a 12v battery.

What's NABSEP certified? Due you mean NABCEP? If so that's a decent accomplishment for sure. But I still have to disagree. The math shows that MPPT will always make more power than PWM.

[time2roll]

https://www.solarblvd.com/product_info.php?cPath=1_270&products_id=3070

Yes they are poly. Not sure the poly vs. mono discussion is worth having again.

Yes shipping is a lot. However people are periodically posting picking these panels up for even less from local solar installs that have a few extras. I paid a nominal charge for local delivery.

[Chandalen]

smkettner wrote:
OK so $550 for 500 watts. With MPPT you could have 530 watts (2 panels) for $200 less.

What panels are that cheap? I did a quick search and I can find some Poly panels close to $500 @265w, but no Mono's.

I went for a larger controller, to allow for expansion.

[Boon_Docker]

Chandalen wrote:


The FACT is, PWM will usually always perform better in a camper/RV type set up. Period.

Not going to bother arguing the point.
You believe what you want to believe and the rest of us will go by the facts that have been proven through numerous comparisons.

[time2roll]

OK so $550 for 500 watts. With MPPT you could have 530 watts (2 panels) for $200 less.
And as shown the 30 amp TS-MPPT-30 would have been fine to save a few more $$.

Really need to fully load or even overdrive an MPPT to get the value. Running half the rating is not a good value.

Still surprised the MPPT was at lower amps. (assumes identical test conditions)

[Chandalen]

smkettner wrote:

Chandalen wrote:
MPPT will be getting close to being on par with a PWM in the 700w area. Above 1000w go with MPPT (usually)

Again, its a cost game.

With my array 500w,

What panels? what cost?

I use 5x Renogy 100w (mono). Their size is perfect to fit 4 across on most campers. They are ~$140 each on Amazon. I went thru Renogy and received a military discount. I paid about $110 each if I remember correctly.

[Chandalen]

Boon Docker wrote:
Anyone wanting to know the pros and cons about controllers, here is a white paper on the subject. Very interesting read that takes away all the heresay that you read on the forums.

/shrug I can pull up numerous white papers from any number of vendors that write the paper to point you in their marketing direction.

Does a vendor want you to spend $450 or $150... lets make a white paper look pretty so people will.

The FACT is, PWM will usually always perform better in a camper/RV type set up. Period. Even the small gain you may see in an MPPT is NOT worth the cost of the controller. Use the money for another panel, and/or better wire, and you would be on top again.

Fun points:

>Systems in which array power output is significantly larger than the power draw of the system loads would indicate that the batteries will spend most of their time at full or near full charge. Such a system may not benefit from the increased harvesting capability of an MPPT regulator. When the system batteries are full, excess solar energy goes unused. The harvesting advantage of MPPT may be unnecessary in this situation especially if autonomy is not a factor.

>The greatest benefit of an MPPT regulator will be observed in colder climates (Vmp is higher). Conversely, in hotter climates Vmp is reduced. A decrease in Vmp will reduce MPPT harvest relative to PWM. Average ambient temperature at the installation site may be high enough to negate any charging advantages the MPPT has over the PWM. It would not be economical to use MPPT in such a situation. Average temperature at the site should be a factor considered when making a regulator choice.

>Low power (specifically low current) charging applications may have equal or better energy harvest with a PWM controller. PWM controllers will operate at a relatively constant harvesting efficiency regardless of the size of the system (all things being equal, efficiency will be the same regardless of array size). MPPT regulators commonly have noticeably reduced harvesting efficiencies (relative to their peak efficiency) when used in low power applications.

[time2roll]

Chandalen wrote:
MPPT will be getting close to being on par with a PWM in the 700w area. Above 1000w go with MPPT (usually)

Again, its a cost game.

With my array 500w,

What panels? what cost?

[Boon_Docker]

Anyone wanting to know the pros and cons about controllers, here is a white paper on the subject. Very interesting read that takes away all the heresay that you read on the forums.

[Chandalen]

MPPT will be getting close to being on par with a PWM in the 700w area. Above 1000w go with MPPT (usually)

Again, its a cost game.

With my array 500w, I tried the following controllers, because I got in a debate with a fellow camper, who just had his friend install an array on his camper. He had the TS-MPPT-45, and I have the PWM version.
Nothing else changed:

Morningstar (PWM) TS-45 Retail price $150
Actual amperage to batteries 27a

Morningstar TS-MPPT-45 Retail Price $450
Actual amperage to batteries 23a

So... for $300 more, I could lose 4a. That's an amazing deal just because people think MPPT is better all around.

For arguments sake. Lets say the MPPT did give 4a more than my set up. I could still spend the $300 I saved on two additional panels, and be back on top.

The charge controller is very important. I went with the MS TS 45 because all its voltages are programmable. Most golf cart type batteries perform much better if you can adjust the voltages to what the mfr suggests. The TS-45 allows this, as well as voltage AND temp sensing at the battery to ensure proper charge.

[Boon_Docker]

How is PWM better than MPPT for a system that is over 400 watts?

[grizzzman]

Chandalen wrote:
Seriosuly... wtf is wrong with posting... keep getting an error, but if i keep my posts to like 4 sentences its ok...

I would go with a PWM controller.

MPPT is usually out performed by PWM in smaller array sizes.

MPPT hates heat. A lot.

Any advantage MPPT could provide in a camper install is negated, or lost when you factor in heat, small array size, likely hood of actually angling the panels when you stop.

Use the saved money for lower gauge wires, a better inverter (PSW), etc..

But what do I know, Im just NABSEP certified.

"And the truth shall set you free"

Many here believe otherwise.

The only issue I have is solar nubbies getting misinformed.

[Chandalen]

ignore

[Chandalen]

Seriosuly... wtf is wrong with posting... keep getting an error, but if i keep my posts to like 4 sentences its ok...

I would go with a PWM controller.

MPPT is usually out performed by PWM in smaller array sizes.

MPPT hates heat. A lot.

Any advantage MPPT could provide in a camper install is negated, or lost when you factor in heat, small array size, likely hood of actually angling the panels when you stop.

Use the saved money for lower gauge wires, a better inverter (PSW), etc..

NABSEP certified.