IS THIS SETUP OK?

PURSITA2 · September 2015

I AM NEW TO SOLAR. I HAVE A DESIGN FOR AN INDOOR EVAP COOLER (WE LIVE IN THE DESERT) ONLY COMPONENTS I AM INITIALLY POWERING ARE A 150 WATT, 12V FAN AND 30 WATT, 12V BILGE PUMP. I CHOSE 12V AS THE COMPONENTS WERE ALL CHEAPER. PLAN BUYING 280 WATT, 36.5V PV PANEL FROM SOLAR WIND. - RUN 36V APPROX 40' TO A 36/24 DC/DC STEP DOWN CONVERTER - TO A 24V/12V MPPT CHARGE CONTROLLER - TO 12V BATTERIES - THEN TO FAN/PUMP. I HAVE ALL PARTS BUT THE PANEL AND BATTERIES. I WOULD LIKE THE SYS. TO RUN A FEW HOURS AFTER DARK (FLEXIBLE). THE LARGER PANEL MIGHT ALLOW AN EXTRA AN OR PUMP AND PROVIDE CHARGING WHILE RUNNING DURING THE DAY. WHAT WOULD BATTERY AMP/HR NEED TO BE? DOES THE ABOVE SOUND OK? MY WIFE WILL KILL ME IF I ELECTROCUTE THE DOG OR SOMETHING. THANKS. RICHARD

solar_dave · September 2015

If you are using an actual MPPT charge controller there is really no need to step down the line before the charge controller, the charge controller will do that.

The key to making this successful is to understand the loads, size the batteries for the needed autonomy then size the panels/ charge controller to get the batteries charged.

vtmaps · September 2015

With that size solar panel you could manage a couple of 6 volt golf cart batteries in series... depending on how often and for how long you run your loads.

But first, you need a sensible system design. What solar controller did you buy? You shouldn't need a 36/24 volt step down converter... the controller should step down from panel voltage to battery voltage. Also, you need some way to prevent the loads from killing the battery... a low voltage disconnect. Some charge controllers have load terminals that can do this.

--vtMaps

PURSITA2 · September 2015

THANK YOU FOR YOUR RESPONSES.THE VOLTAGES I CHOSE SEEMED TO REQUIRE THE LEASE COSTLY COMPONENTS. THE CHARGE CONTROLLER I HAVE IS AT http://www.ebay.com/itm/30A-12V-24V-Auto-Switch-MPPT-Solar-Panel-Battery-Regulator-Charge-Controller-KJ-/201132329820. MY UNDERSTANDING THAT THE MAXIMUM INPUT VOLTAGE IS 24V DC..SINCE IT COST $19 INSTEAD OF $100+,. I WENT THAT WAY. DID I READ WRONG?

oil pan 4 · September 2015

You only bought one cheap charge controller.

I would not expect it to last nearly as long as a name brand charge controller. Should have picked up a spare.

Photowhit · September 2015

PURSITA2 said:

THANK YOU FOR YOUR RESPONSES.THE VOLTAGES I CHOSE SEEMED TO REQUIRE THE LEASE COSTLY COMPONENTS. THE CHARGE CONTROLLER I HAVE IS AT http://www.ebay.com/itm/30A-12V-24V-Auto-Switch-MPPT-Solar-Panel-Battery-Regulator-Charge-Controller-KJ-/201132329820. MY UNDERSTANDING THAT THE MAXIMUM INPUT VOLTAGE IS 24V DC..SINCE IT COST $19 INSTEAD OF $100+,. I WENT THAT WAY. DID I READ WRONG?

I think you are inexperienced with solar and eBay. Please check the sellers feedback. Click on the 6 month negative feedback and you will see many people are letting you know that this is NOT as advertised It is really a PWM type charge controller.

Might look around at others ideas on evaporative coolers / swamp coolers. Some in have even experimented with a simple misting hose above a fan (much smaller than 150 watt!) Good Luck. If you have the grid use it! unless you just want to experiment those who have gone before you will tell you it's cheaper!

PURSITA2 · September 2015

APPRECIATE YOUR RESPONSE. SELLER SHOWS 5 STARS IN ALL CATEGORIES SINCE 2011 ON EBAY. I HAVE ASKED FOR A RESPONSE TO YOUR COMMENTS. THANKS AGAIN. RICHARD

Mountain Don · September 2015

That ebay seller seems to sell more fashion items that technical items. That in itself does not necessarily make them a cheat, but there are negative comments about the quality of the controller. I would guess that many of the positive comments about the CC come from people without a clue about solar and electronics. Some of the claims made by some China sellers are incorrect at best and outright lies at worst. We are simply passing on experiences. With solar electronics cheap does often lead to disappointment.

PURSITA2 · September 2015

THANKS AGAIN FOR ANSWERING. I COULD NOT FIND THE NEGATIVES RE THIS CC. EBAY LISTS 102 POSITIVES. I AM WILLING TO LEARN - CAN YOU CITE THE CRITICS?

oil pan 4 · September 2015

Yes I too have bought Chinese electronics off ebay there were out right lied about. Fortunately none has been solar related.

That is why I ask here first then buy.

Mountain Don · September 2015

Page 1 and page 2 of the negative comments each have a negative remark about the so called MPPT controller. I searched no further than that as I felt no need to. The unit in the photo doesn't even claim to be MPPT, not that that would be a reliable thing to go on.

I have bought a lot of small electronic parts from Chinese sellers. I have had my share of deals gone wrong; goods shoddily made; and some outright lies about products shipped. This is a Chinese seller who happens to have a USA warehouse distributor. Many do, that does not make them any more reliable than sellers who ship from China. I feel that Chinese direct purchases are sometimes like a lottery. Don't spend the money unless you can throw it away. But I have had a batting average high enough that the occasional $6 or $8 item that fails miserably has been more than made up for by all the winners. However, I am suspicious of, and don't buy, things that seem too good to be true. An MPPT controller under $20 falls into that category, IMO. A PWM controller for that, maybe. The simple fact that the controller does not accept incoming voltage over 20-some volts is a big red flag to anyone who has some knowledge about controllers and how they function.

solar_dave · September 2015

It is virtually impossible to make and sell a MPPT charge controller for $18.55. It is most like a PWM and not a very good one at that. Most have a programmable interface for voltages and duration.

Solar is not cheap for quality equipment.

PURSITA2 · September 2015

THANKS GUYS. I'LL LET YOU KNOW.

IS THIS SETUP OK?

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