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Old 05-15-2017, 09:39 PM   #1
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Solar Panel comparison

Hey Skoolie Peeps!

I was wondering if anyone would kindly care to have a look at this. I'm comparing solar panels, I have been keen on Renogy, was briefly interested in Grape Solar but I think they're more expensive than Renogy. Then I found Sainty Solar and it seems to me they give you even MORE bang for your buck.

https://www.amazon.com/Sainty-Solar-...r%2Bpanel&th=1
This 4 piece Sainty Solar kit would give me 1020watts for $870.

https://www.amazon.com/gp/product/B0...w_c_x_1_w?th=1
This 4 piece Renogy solar kit would give me 400 watts for $560.

Surely I'm not missing the obvious.... my only hesitation is that Renogy has a LOT more reviews with higher star rating than Sainty Solar. But GOOD GODS that's more than twice as much wattage for the same price. Please tell me, am I missing something PAINFULLY obvious here?

Also, I was thinking of this charge controller:
https://www.amazon.com/Morningstar-T...rningstar+MPPT

Would this suffice for one of these systems?

I was thinking of these batteries:
https://www.amazon.com/dp/B00CIYRR0C...electronics-20

HandyBobSolar recommended them, would that work? Would I need more?

PLEASE and THANK YOU yall, I hate to be like this, I feel like I'm asking everyone too much, but I'm trying to work on all this, I just need someone to check my work. Yall are awesome... if we ever run into each other on the road ask me for my not-at-all-famous-but-super-tasty curry!!! <3 I'll whip out my rice cooker and portable induction cooktop and use the electricity yall helped me check for supper!!!
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Old 05-15-2017, 10:32 PM   #2
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Both panel manufacturers have about the same quality, efficiency, and type of cells. Obviously the 255W panels are going to take much more roof(?) real estate than the 100W panels.

The Morningstar MPPT charge controller is an excellent choice. Keep in mind that you're going to get 45AMPs of charge (maximum) regardless of battery voltage of 12V, 24V, or 48V. For example, you would want to charge a 24V array of batteries if you were to go with the 4x255W panels. With the 400W array you will be below maximum output of charge controller keeping a 12VDC bank.

Run the solar array in series either way to provide a higher voltage and take advantage of the MPPT of that particular controller.

Those batteries are great and about appropriately sized for either solar choice. The 400W array may have more difficulty replenishing the charge.

I guess the main thing to really consider is your usage and desires for the power system you're designing...
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Old 05-15-2017, 10:37 PM   #3
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...to add: Solar efficiency is key when space is at a premium; cost will also be significantly impacted.
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Old 05-16-2017, 12:24 AM   #4
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I have two of the Morningstar TS-MPPT-60 charge controllers for my bus's PV system - so far so good, no complaints at all. I use eight Sharp 255W panels which are about 40" by about 5'6" (as far as I can remember), hinged on either side of a central walkway between my two roof hatches: four panels occupy about 22 feet of roof length, leaving me another few feet for two eventual 20 sq.ft. solar water heating panels. Each side of four panels is wired in parallel and feeds its own CC that will charge four GC2 batteries, with each battery bank connected through 250A Schottky diodes to the DC load center and inverter(s).

I think almost $1000 for four batteries is preposterous! It's generally assumed that everyone murders their first set of batteries because of inexperience or worse, so I suggest first using the cheapest that will work, then if they die after a year or two it's no big deal. Costco has Interstate golfcart batteries for less than $90 each - that's more like it. Trojans also need slightly higher voltages for charging, but Morningstar TS-MPPT CCs can be set for them.

Panels shouldn't be more than a dollar a watt. I paid much less than that, partly by buying Grade Bs with cosmetic blems (but still UL-listed), and partly by buying from a wholesale distributor that mainly supplies installers. Don't buy from non-specialist retailers like Amazon or Home Despot, and pick them up yourself to save on exorbitant trucking costs. PV these days is a generic commodity, and there's little difference in quality between one brand and another if they're UL-listed. I don't think it matters much where the panels are made - the Chinese and Indians now produce panels as good as anyone else's. Just don't use flexible panels or used take-offs of unknown ancestry.

Shop around and do some research, and you'll save hundreds or even thousands of dollars. Read the NAWS forum for no-BS advice!

John
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Old 05-16-2017, 07:10 AM   #5
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the only down side to Morningstar is you cant program the exact charge specs without the remote panel. I'm using the outback mx60, its been running for 12 years now no problems. the last panels I bought were drop shipped from ebay, I got 6 250 watt grade A panels for 1230 bucks delivered to my door. go with the cheap 6 volt g c batteries, the solar learning curve can get expensive. if you get an inverter get a inverter/charger, if your batteries get low you need to bring them up fast. most of them will charge at a 100 amps. get a bogart 2030 battery monitor with the 500 amp shunt to keep track of your system. good luck
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Old 05-16-2017, 01:23 PM   #6
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Thanks for the input guys!

I probably should go for cheaper batteries, I had the trojans saved because HandyBob recommended them, but if cheaper ones would work in the meantime I should probably go with that. Good thinking. 1K for 4 batteries DID seem pretty dang gratuitous to me. I know HB has 345w and 4 trojan 6V batteries, and that's a balanced system. So I was wondering if 1020 watts of solar wasn't badly balanced with 4 batteries? If I move to MN like I want, I'll be in solar zone 4, so average of 4 hours of solar charge a day.

I had trouble finding charge controllers on Amazon, I'll look somewhere else as well, where did yall buy yours? I seem to be in the middle of nowhere here in the midwest region. I think we have an RV store north of us but they're bound to be overpriced, and from what I read they sell crappy stuff too.

I searched around on solar panel prices and Sainty Solar seemed to give the most for the least, aside from possibly sunelectrics.

Do kits usually come with decent hardware? Or am I better off getting the rest separately? HB decries the thinner gauge wires for voltage drop....
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Old 05-16-2017, 02:02 PM   #7
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There's a lot of parts and pieces out there for PV systems. I don't know that much about this subject but wanted to research it. The easiest way I found to start understanding PV systems was to study the good kits, then try to find equal or better individual pieces that could be used to make up that kit. It's a fast way to learn without getting off track.

It's been a couple years since I researched PV systems, but then putting the kit together yourself could result in prices as low as 50 cents per watt. That's the difference between buying a kit and buying the pieces, maybe hitting a few sales. Buying your own pieces can also easily allow for future expansion of the system.
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Old 05-16-2017, 05:53 PM   #8
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1020 watts of panels is perfect for four golfcart batteries. That's essentially what I have, and I chose that because the batteries could be charged at up to the maximum 13% charge rate for FLA batteries. I feel that on a bus or RV roof that is probably not ideally oriented to the sun most of the time, you need more instead of less PV power to compensate. Some folk seem to be getting by with much less PV for the same amount of batteries, but only time (and a good hydrometer) will tell if they have avoided long-term deficit charging that inevitably leads to gradual but permanent plate sulfation and an early end to the batteries' life. In an ideal world one should be getting six to eight years, maybe more, of useful life from a well-designed PV system's batteries, but getting that on a bus is less likely. Having lots of PV power stacks the odds in your favor.

For the hardware, don't bank on much of it being useful for a bus installation! Panels are not attached the same way to a bus roof as to a house roof, so you may well end up making your own brackets and mounts anyway. A marine setup is probably closer to what a bus needs than a typical house installation. Whatever you do, don't cheap out with cables and connectors - most kits come with pathetic little cables not much good for anything. Buy a proper circumferential lug crimper such as the FTZ 94284, use tinned closed-end lugs and good heatshrink, and use fatter cables than the specs say to reduce high-current voltage loss to less than 3%, ideally to 1% or less. (I just use 4/0 for almost everything to/from the batteries!) Blue Sea makes decent switches and fuse blocks, not cheap but quality never is. Pretend you're installing it on a boat and it will need to be inspected by the USCG!

John
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Old 05-21-2017, 09:54 PM   #9
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There are a lot of good replies here. I'd like to chime in because this is something I'm actually pretty knowledgeable on. I run a small renewable business and dealt with the
grid-tied residential stuff before I got into off grid. I also have a big system on my bus.

I had choices with the panels too, and thought about using residential panels. But unless you're sourcing them locally you'll pay freight shipping. The Sainty Solar panels you referenced will work. In your climate zone I would pack your roof with as much solar as you can get. Even with 1kW on your roof (1000w), at 4 hours a day, you're only pumping 4kWh into your battery bank ... and that's an unrealistic number because of some efficiency losses. It might not be enough, depending on what you want to do. As John mentioned, with a good charge controller you can't really overcharge. You can undercharge though, resulting in excess sulphate. That's no good on expensive batteries. I just hope the Sainty panels don't drop in efficiency super fast like some of the real cheap Chinese panels.

I went with the Renogy panels ... they were too good to pass up. They are so easy to deal with and the return policy with Amazon is nice. Yeah, you can get cheaper panels, but Renogy is a big enough company that they back their stuff up. I spoke to their techs about a dead panel. They sent me a return shipping label near immediately. Sure, they are cheap panels too, but they are putting out their rated current. They also fit nicely, width wise, on my bus. I got 12 up there easy. I have mine running in two strings of 6 panels each. They each pump ~120v and my Morningstar Tristar MPPT 60 controllers do their job and give my battery bank whatever it needs. Also depending on how you wire your system, 4/0 is way overkill from the panels to the controller. I am using the standard 10 gauge MC4 connector wires that Renogy sent me and they work well. I am keeping my amps real low though (~5.5amps) and letting my MPPT charge controller do the work.

And someone said you can't custom program a Morningstar controller without the remote meter -- that's untrue. You do need an RS232 to USB adapter, which you can find on Amazon for $10 shipped. I do recommend getting the correct meter though. It is worth the $130. The software is also real easy.

I think your original battery bank is light depending on what you plan to do, though. 'Four golf cart batteries' doesn't mean anything. You have to know exactly how much power they're going to put out. As for those Trojans you referenced ...

225aH x 4 at 6 volts = 1000aH. At 12v, which is probably what you'll be using with most entry inverters, it's 500aH. You should only be using half of that and never discharging below 50%, so now you have 250aH usable. Depending on your energy consumption this is not as much as you think. Especially if you have a few rainy days or are thinking about a residential fridge or a small air conditioner or a television or computer, et cetera. For comparison, my battery bank is 860aH at 12v and that means I have 430aH that I can actually use. I'd love more. Also, HandyBob recommends the Crowns over the Trojans last I checked.

And I do disagree with the other replies. I think you should invest in a good battery bank. You won't destroy the batteries your first time around. If you destroy your battery bank with that charge controller ... I don't know what to tell you. It is SO awesome. You set it and forget it. In fact, I can't imagine a scenario where you could improperly charge your batteries if you programmed your charge controller correctly. Just make sure you watch the electrolyte levels when you EQ and top off with distilled water as needed. And most importantly, IF YOU GET GOOD BATTERIES THEY TAKE A BEATING. I was using the standard L16 charge settings for my batteries and they were being overcharged a little for a week or two. Turns out the CR430's like a little less voltage. I called Crown and the tech shrugged. "These batteries can take some overcharging. Don't sweat it." He then walked me through all the proper charge settings. If you do end up getting Crown batteries, I have four CR430 batteries that I got from a seller on ebay. I can send you the link. I think I paid $1300 shipped to my door. I'd send you the custom charge template for your Morningstar charge controller.

But seriously, why spend 100 bucks or more on a cheap battery to 'learn' when you can spend 300-330 for a battery that may last you 5-10 years? Solar is the type of project that I think you should do right or not do at all, because cheap components wont last and you'll be scratching your head and asking yourself where your money went.

Just my two cents.

PS - You can find the Morningstar TS-MPPT 60 on Amazon. Shipped via Prime too I think.
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