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LastOutlaw Member	# Posted: 15 Sep 2014 12:23 Reply I've purchased three 300 watt panels and am now looking at which charge controller would be best for my use. I would like to possibly have some leeway to expand into more panels in the future so having a charge controller that allows expansion would be nice. Most important is an affordable mppt charge controller that will handle the parameters of these panels. Here is the info on the panels and the info on the charge controllers that I am considering at this moment. Please feel free to point out and pluses and/or minuses that I may not see. Panels are the 300 watt panels. http://renogy.com/wp-content/uploads/2013/12/RNG-290295300305310P-IV.pdf Here is the info on the CC's that Im considering: http://www.blueskyenergyinc.com/uploads/pdf/BSE_Product_Line_Overview.pdf I think the 3000i will be too small handling only 400 watts? or am I reading this wrong? The 3024il looks like it would work but may do a lot more than I need it to. Would appreciate your thoughts on these CC. Thanks, LO

VTweekender Member	# Posted: 15 Sep 2014 13:04 Reply The panels will be 24v ' so your controller will need to allow 24v. They output about 8 amps each so with 3 panels you would need the 30 amp controller, if you want to add the same panels in the future to the same controller then you will need to get the 50 amp controller.

MtnDon Member	# Posted: 15 Sep 2014 13:20 Reply Missing from your question and data is what the voltage of the proposed battery bank will be. Or is that open? Also has the capacity in amp-hours or watt-hours been decided yet?

LastOutlaw Member	# Posted: 15 Sep 2014 13:36 - Edited by: LastOutlaw Reply Thanks as always for your input Don, and also thanks for yours as well VT. Right now I'm utilizing a 12 volt battery bank of six ac/delco voyager deep cycle batteries. (m29mf) I can add more of these if needed in the near future once these are paid off and can be switched to a 24 volt bank if that would be better. ( I bought them on a payment plan at work) I am presently utilizing a harbor freight 2000/4000 watt power inverter that really must be more like a 1000/2000 watt inverter as it can not handle a 2000 watt load. This inverter can be switched for a higher end unit in 24 volt if need be in the near future if I'm better off running 24 volts in the bank..

MtnDon Member	# Posted: 15 Sep 2014 13:59 Reply Those 300 watt panels have a Voc of 46.12 volts. An Isc of 8.56 amps. For the voltage you also must factor in the safety factor. NEC code states to multiply the Voc x 1.25 x 1.25 to get the system maximum likely voltage. (multiply the Voc x 1.56 for simplicity). Or use a system sizer calculator like the ones that are available for MN, Otback and upper line Xantrex/Schneider. Those have adjustments for the locales maximum and minimum temperatures. The NEC code requirement assumes the worst; not all places have - 30 to -40 degree temperatures. (the colder the temperatures the higher the PV voltage output. And the reverse for high temperatures. So with that in mind, on first glance, the only Bluesky CC that might do the job is the Solar Boost 3048L. That will only work if the panels are in parallel and only if the battery bank is 48 volts. This opinion does not come with any warranty of true suitability to the system you propose. It may be cutting the capacity of the advertise specs on the CC a little too fine.

MtnDon Member	# Posted: 15 Sep 2014 14:20 Reply Quoting: LastOutlaw I'm utilizing a 12 volt battery bank That really limits the total PV watts that you can use.

MtnDon Member	# Posted: 15 Sep 2014 14:30 - Edited by: MtnDon Reply Quoting: LastOutlaw 12 volt battery bank of six ac/delco voyager deep cycle batteries. (m29mf) I can add more of these if needed in the near future once these are paid off and can be switched to a 24 volt bank if that would be better. Do yourself a favor. If those batteries can not supply the reserve capacity of power you end up using, do not buy any more of them. Having six of them in parallel is already too many in parallel. They are not true deep cycle batteries like a golf cart battery or a battery advertised as suitable for RE (renewable energy) use. One of the clues to this is the absence of the amp-hour capacity at the 20 hour rate, in the battery specs. Another clue is the presence of the CCA rating; true RE batteries do not have CCA ratings, but do have the 20 hour amp-hours. Adding more new batteries to any battery bank that has been in service "a while" is a bad idea. The definition of having been in service for "a while" varies from 3 - 4 months to a year depending on who you talk to. That applies to even the super duper special RE batteries made by Trojan, Surrette, Crown, etc.

MtnDon Member	# Posted: 15 Sep 2014 14:50 - Edited by: MtnDon Reply One solution would be... One MN Kid CC with all 3 PV panels in parallel and a 48 VDC battery bank. BUT, there is a problem with the maximum voltage from the PV array in parallel not being high enough to permit charging of a 48 volt battery bank. Sometimes anything but the smallest simplest PV system can be a real challenge in finding equipment that will work together.

MtnDon Member	# Posted: 15 Sep 2014 14:57 - Edited by: MtnDon Reply Quoting: LastOutlaw .....12 volt battery bank of six .... (m29mf) I can add more of these if needed... Adding more new batteries to a system already in service has pitfalls. Depending on who you talk to, what you read, the "add some batteries" window can vary from 6 months to a year. What happens is the new batteries act like the old ones with diminished performance. Keep in mind one of the most important aspects of designing a workable system is to know how much power is needed from the batteries on a daily basis.

LastOutlaw Member	# Posted: 15 Sep 2014 15:10 - Edited by: LastOutlaw Reply Right now the draws I know of are a window mount ac unit that draws 10.5 amps when the compressor kicks in and about 1.5 amps when normally running which would not be always running and a converted chest freezer being used as a fridge which draws 1.5 amps when the compressor is on once for a few minutes every hour or so. We would sometimes run a laptop and a couple 40 watt lights. So far that is the load we are using. Now this may vary if we need to charge a rechargeable battery from time to time.

LastOutlaw Member	# Posted: 15 Sep 2014 15:20 Reply It sure is hard finding the right equipment to make this work right.

MtnDon Member	# Posted: 15 Sep 2014 15:26 - Edited by: MtnDon Reply Quoting: LastOutlaw a window mount ac unit that draws 10.5 amps when the compressor kicks in and about 1.5 amps when normally running Quoting: LastOutlaw chest freezer being used as a fridge which draws 1.5 amps when the compressor is on once for a few minutes every hour or so. For best results (happiest owner and owners spouse) those need to be expressed as an amount of power in a day; so many amp-hours @ nn volts or in watt-hours. Running the appliances through a Kill-a-Watt for several typical days can help determine actual use. Then apply a factor to correct for battery charge/discharge loses and inverter losses... maybe up to 20% to be safe. Quoting: LastOutlaw couple 40 watt lights. Go for some of the new LED bulbs like the 120 VAC Cree or Osram. We have the Cree that are 9.5 watts for the 60 watt incandescent equivalent.

LastOutlaw Member	# Posted: 15 Sep 2014 16:41 - Edited by: LastOutlaw Reply Well we really don't expect to be running the ac full time and not always off of the batteries. I'm estimating that we would run ac for a few hours at night off of the battery bank...anywhere from 3 to 6 hours if possible. Daytime use if the wife is working inside would be run off of the eu2000i as much as possible in order to save battery for night use. the freezer/fridge conversion would be running full time and pulled just over 1/2 kilowatt in a 24 hour period on max cold setting this past weekend in tests. I wont be back to the cabin until next month to run tests on the a/c draw with the kill-a-watt. I'll try the bulbs you recommend when I go up there again... thanks for the tip.

LastOutlaw Member	# Posted: 15 Sep 2014 16:52 Reply I don't mind dumping the inverter i have now and re-configuring my bank to 24 or 48 volts if I can get this system working well at a decent price. Quoting: MtnDon One MN Kid CC with all 3 PV panels in parallel and a 48 VDC battery bank. BUT, there is a problem with the maximum voltage from the PV array in parallel not being high enough to permit charging of a 48 volt battery bank. I think I plugged the info for these panels into the MN software and it said the KID wouldn't work. It suggested the lite 200 or something else. If not I would have already bought one... I liked the info on it.

MtnDon Member	# Posted: 15 Sep 2014 18:10 - Edited by: MtnDon Reply Here's a thought that works with 1 Kid charge controller 4 of the 300 watt panels; 2 series strings of 2 panels each and those series strings connected in parallel 48 volt battery bank buy 2 more of those batteries; 2 series strings of 4 each, connected in parallel Then when those batteries die buy some real RE batteries (like L-16's) or at least golf cart batteries

MtnDon Member	# Posted: 15 Sep 2014 18:22 - Edited by: MtnDon Reply That has the Kid working at half capacity (amps) more or less. Better than working close to the maximum, as far as theory goes. It also cuts the parallel batteries down to only 2 deep; much better than as is now. If those batteries are about 115 amp hours each then you would have 115 x 2 = 230 AH @ 48 volts = 11040 watt hours. At 50% max discharge = about 5 Kw usable power. 230 AH would be served well with a 20-25 amp charge input. The 4 panels on the Kid would supply 21 amps at 57.6 volts (equiv to 14.4 on a 12 volt battery). Just about ideal for charging. Now find a 48 VDC inverter.

MtnDon Member	# Posted: 15 Sep 2014 18:28 - Edited by: MtnDon Reply Quoting: MtnDon Then when those batteries die buy some real RE batteries (like L-16's) or at least golf cart batteries Eight 6 volt golf cart batteries in series = 48 VDC. About $680 at my local Sam's Club today (plus core charges of $15 each, and the used up batteries would cover that). That is roughly the same AH capacity as 8 of the present 12 volt batteries and should perform better. 8 - L-16's could be about double the power @ about $2400... the golf cat batteries would be a good deal.

LastOutlaw Member	# Posted: 15 Sep 2014 19:05 - Edited by: LastOutlaw Reply sounds great! i like that idea except...The batteries are already on order for 3 of them. I had to order at least 2. Ordered 3 as that was within the budget I'm already over...LOL. Back to juggling funds to make it happen. Maybe since they are on back order I could contact them to see if they can add one more to the order. Off to juggle. Thanks again Don.

LastOutlaw Member	# Posted: 15 Sep 2014 21:19 Reply And I just got an email that my order has shipped. I thought they didn't have any until Oct. 1. grrrrrrr. Never thought I would be upset that someone shipped too quickly.

LastOutlaw Member	# Posted: 16 Sep 2014 09:49 Reply Quoting: LastOutlaw The batteries are already on order for 3 of them. I had to order at least 2. Ordered 3 as that was within the budget I'm already over I meant the panels are already on order. Not the batteries.

LastOutlaw Member	# Posted: 16 Sep 2014 14:19 Reply Looks like I am screwed on this idea. The 3 panels ordered while they are on back order have already shipped. Guess they had 3 left in stock after all. I just got off the phone with them and if I want one more 300 watt panel for $234.00 I will have to pay $250.00 shipping. Deal killer. Not sure what to do now. Order two 250 watt panels and run uneven strings then sell off the extra 300 watt panel to recoup some of the loss?

MtnDon Member	# Posted: 16 Sep 2014 14:48 - Edited by: MtnDon Reply Too bad you couldn't add 1 panel to the B/O. A further question though... What is the distance between the PV array and the CC? Short like most systems; less than 20 feet or so of wire? Or longer? That can affect whether or not panels would be better off in series or parallel. ~~~ I am not familiar enough with the stacking of the MN Kids to be certain of this, but is my impression that you could connect 2 panels to one Kid and 1 panel to the second Kid and run them in 'follow me' mode. The CC with 2 panels could be series or parallel by the looks of it. You could check with MN on that, or ask on their forum. However it would be less expensive to buy a single MN Classic 150 Lite than two Kids. (two Kids = $570; Classic150Lite= $500 at NAWS) The 'Lite" version use a display similar to The Kids, whereas the non Lites have the more informative LCD display. But $610 will get you a Classic 150 or 200 (regular version and display). You would need a Classic200 or a Lite version, to run 3 of those panels in series. However if there is no real need to run the panels in series the 150 version would handle your panels in parallel. Those ideas are based on running a 24 volt battery system; not a 12 and not a 48. The only advantage I see to running 2 Kids would be the redundancy factor. If one had a problem you could limp along with one CC and two panels. OTOH, the likelihood of having an operational problem is low, IMO, when you stick with the upper echelon of equipment; Outback, Midnite, Schneider/Xantrex XW series. The odds of trouble with quality equipment is about the same as being struck by lightning.

groingo Member	# Posted: 16 Sep 2014 14:59 - Edited by: groingo Reply Looks like I am screwed on this idea. The 3 panels ordered while they are on back order have already shipped. Guess they had 3 left in stock after all. I just got off the phone with them and if I want one more 300 watt panel for $234.00 I will have to pay $250.00 shipping. Deal killer. Not sure what to do now. Order two 250 watt panels and run uneven strings then sell off the extra 300 watt panel to recoup some of the loss? Don't beat yourself up, solar is the never ending journey and as long as you learn from every mis step it will only keep getting better...besides I just ordered my first solar setup from Renogy yesterday myself so I can put what I have learned here to the test, we have some great resources here so fear not!

LastOutlaw Member	# Posted: 16 Sep 2014 15:44 - Edited by: LastOutlaw Reply I haven't given up on trying to get the 300 watt yet. i have a call in to them to see if they can ship one panel UPS. it should fit within their shipping limitations. Under 70 lbs, under 9 feet in length. Waiting on a return call. if they make this happen i will sing their praises all over the interweb. Don, the distance from cabin to sunny spot is 50 ft. From front of cabin to back of cabin where the bat bank might sit is another 50 ft. The 48 volt system would have worked out nicely allowing a smaller wire gauge used. I am considering building a small solar cabinet closer to the array and then sending power in inverted form of 120 volts to the cabin but am concerned with theft while I am not there. Once we moved in perm that would much less of a concern.

MtnDon Member	# Posted: 16 Sep 2014 18:30 - Edited by: MtnDon Reply Quoting: LastOutlaw I am considering building a small solar cabinet closer to the array and then sending power in inverted form of 120 volts to the cabin That often does not make much difference. It hinges on what the AC amps might total and what the DC amps might be. In our case the difference in wire gauge was insignificant. That was based on the facts of the DC from PV to CC being only 8 amps maximum (all panels in series) and the AC amps being up to the capacity of the inverter; 3500 watts = 30 amps. That was a wash and having the batteries right at the cabin made more sense in our situation. Because I wanted the ability to use the maximum of the inverter (power tools, whatever) I used that as the AC amp load. That was probably overkill, but that is the way I looked at it. Run the numbers. I can run my calculator for you if you want. The variables are; AC or DC volts max amps aluminum or copper wire Given the conductor gauge and one way wire length I can solve for voltage drop Given the desired limit of voltage drop (%) and conductor gauge I can solve for wire length Given the desired limit of voltage drop (%) and wire length I can solve for conductor gauge. Voltage drop should be kept to 3 to 5% in 120 VAC and higher. In low volatge DC it is better kept under 3%, under 2% is better yet. Ours is around 1% at maximum DC power.

LastOutlaw Member	# Posted: 16 Sep 2014 19:21 Reply To be honest after talking with you and reading up on the benefits of higher dc voltages in both pv setup and battery bank I'm pretty convinced the higher voltage/lower amp setup is more beneficial and the wire size/distance issue seems to become less and less of a problem as the voltage goes up due to wire size demands diminishing. After plugging in the info on 48 volt array with low amps at 50 ft the wire size demands were around 10 awg. i would try to run at least 6 or even lower especially if I could find a deal on some.

MI drew Member	# Posted: 17 Sep 2014 16:46 - Edited by: MI drew Reply I am also running a Renogy setup and I'm very happy with it. As of now I just have 2 100w mono panels with their Tracer MPPT 40amp controller. If your only running 3x 300panels at 24v youll be just fine. The controller was only about $200 and I'm very impressed with its output. I'm getting up to 14amps in full sun with just the 2 panels and I'm ordering 2 more. I was quoted by Renogy that I'll be seeing 33-34 amps with the 4 hooked up. It will take up to 500w at 12v string and 1000w with 24v string. Currently I'm only running 2 6v batteries at 215ah and plan on purchasing more as the need arises plus more panels. At some point I'm looking at having 8 panels + 8 batteries at 24v and 430ah. Renogy currently has their big MidNite Solar 200v on sale for $700 if you want to go real big. The Tracer is maxed out at 100v DC.

creeky Member	# Posted: 17 Sep 2014 17:14 Reply Re: wire deals. It's fall. You could check around at the local electrical places and see if they have any "end of roll" specials. I'd look at the Morningstar controller. Mppt-60. It gives you some grow up room, has lightning protection built in and a web server in the event you care to track your solar production. You just plug a regular RJ-45 cable into the controller and into your router and presto. All kinds of cool numbers. Useful for tracking your power output. That's an awkward size for the panels. 3 could almost be run at under 150 volts. But one cold day and "magic smoke." Wait a minute. Didn't Aims have a higher voltage mppt controller. Yes! Okay. Have a look at the Aims mppt controller. It's got a 192 max voltage. That'd let you run all three in series. There's a 40 amp. Perfect. Who bought an Aims system? Just recently. You might do a search for his posts.

MtnDon Member	# Posted: 17 Sep 2014 22:10 - Edited by: MtnDon Reply Why would anyone buy a Chinese made AIMS over a Made in the USA MidNite Kid or Classic series charge controller when the MN pricing is so good? And the Classics come with built in GFP and arc fault protection as well as their WhizBang battery SOC meter system.

LastOutlaw Member	# Posted: 18 Sep 2014 09:29 Reply I'm still not giving up on the 4th panel. I have contacted UPS and they will pick up the last panel at the Renogy loading dock and ship to me for about $60.00. Put some insurance on it and I should be good. I've also found some wire in the next major city. 220 feet of thhn 4awg for $100.00. Brand new, unused.