View Full Version : Reliable Charge Controller, Inverter
January 7th, 2007, 19:20 PST
I am curious as to what you (N Arizona Wind and Sun) consider the most trouble-free charge controller and inverter for an off-the-grid PV system in Mexico. I worry that in the future repairs and spare parts could be difficult to get. My system would be around 1kW with AGM batteries (24VDC) using DC lighting, DC refrigerator, and an AC inverter in the 1100-to-1500 Watt range.
January 7th, 2007, 20:46 PST
i'm not speaking for naws, but you bring up an interesting question. i submit to you that there are no guarantees and predicting the future is difficult. besides the obvious business risks and their ups and downs there could be a breakthrough in technology in years to come that could make all we have now obsolete. my advice is to stay with proven quality products. our host carries quality products from those companies that make them. beyond that it's your personal needs, tastes, and affordability that determine which one you buy. anybody else with something i missed?
January 7th, 2007, 21:53 PST
I just had this conversation with NAWS about inverters when I ordered a Trimetric the other day. The Exeltech units are awesome and have a MTBF of about 20 years. I have two of the XP1100's in 48 volt version and they are very good, run anything I plug into them, but will not stack to get 220 or parallel to get more than 1100 watts. I have also had good luck with Trace C-40's, and have had 3 since 1999, however, one has failed. Other than that, they work very well as charge controllers.
January 8th, 2007, 5:00 PST
Considering your proposed system size and location, I’d suggest the following:
1)* Charge controller. Factoring in generally warm ambient conditions and overall array size, I don’t think that an MPPT controller will be of any great benefit to you. Accordingly, I recommend a Morningstar Tristar 60 with its optional digital meter and remote battery temp sensor. Considering that typical mid-day bulk stage charge current from your “24 V” array will be* 1,000 W STC x 85% / 28 V = ~30 A, the 60 shouldn’t ever be stressed. You might want to consider also buying a TriStar 45 as a backup (same physicall size and connections, and the optional meter and RTS can be switched over). Both TriStar controllers plus the meter and RTS will cost less than an OutBack MX60 controller alone.
2)* Inverter. I agree that the Exeltech XP true sine-wave (TSW) inverters are definitely worth considering. Do not even begin to consider a modified sine-wave (MSW) inverter. Exeltech's MTBF claims are impressive, and they appear to be conservatively rated. For example, their power output specs are in real Watts (Volts x Amps x power factor, and not just Volts x Amps), and their full-power temperature spec is 30 C (86 F) as opposed to the usual 25 C (77 F). Inverter efficiency is important as well, as higher efficiency means less waste heat and longer operating time for your loads.
The OutBack FX2524T inverter (2500 VA, 24 VDC in) might be another candidate. It's a very rugged and high quality TSW inverter, and it includes a batetry charger that might be helpful for charging your batteries from a generator during a prolonged stretch of bad weather and/or heavy loads. It's not cheap, but no good inverter is, and, in addition to the battery charger, it's rated at 2,500 VA.
3)* Finally, your location’s warm ambient temperatures will reduce the power output from your PV array. Specifically, you may see output power that’s ~85% of the nameplate rating, and essentially all of this loss will manifest itself as reduced array output voltage. Accordingly, you’ll want to specify 12 V PV modules with an STC Vmp spec of at least 17.0 V. Personally, I’d shoot for something in the >/= 17.3 V range. If you’ll looking at “24 V” PV modules, you’ll want to double those numbers.
You'll also need a safe and reliable way to electrically integrate the PV array, the controller, the inverter and the battery bank. Something like the E-Panel Lite (for the Exeltech inverter) or a regular E-Panel (for the OutBack inverter) from Midnite Solar might get you started in the right direction. See: http://www.midnitesolar.com/MidNite-Products.html
HTH, and good luck!
Jim / crewzer
January 8th, 2007, 6:24 PST
Do you get much lighting in youre area? High Voltage surges induced from even a nearby strike, can fry stuff, if not properly protected.
Heat is likley the most important factor, cooler parts, generally, last longer than parts at their extreme limit. I have a small desk fan on my inverter heatsink in summer, when the inverter is running full power.
January 8th, 2007, 10:05 PST
I too purchased an Exeltech inverter partly because of their impressive MTBF claims, and also because they're made in the USA. Some of the bargain-priced inverters are made in China. Look at the Exeltech website and I think you'll be impressed. Then try to do that with another inverter brand and see what you find.
January 13th, 2007, 13:49 PST
Thank you so much for your thoughts and recommendations.
January 19th, 2007, 20:53 PST
for the record, outback is made in usa too.
February 10th, 2007, 17:00 PST
I would suggest going with an Outback FX inverter and the Outback MX60 charge control. We have around 30-40 Outback systems installed all over Mexico and they have preformed extremely well.
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