New to solar, starting with a BP SX170B 24v panel...what next?

3 Posts
Apr 22, 2011 07:13 pm
New to solar, starting with a BP SX170B 24v panel...what next?

I recently acquired a BP SX170B PV panel and would love to build a stand-alone system for our camping vehicle.  170 watts is a bit of overkill but it's what I have to work with.  Smiley

So I'm trying to put together a system of an MPPT controller, an inverter (for a little bit of 110V power)and two pairs of serially-wired 6v golf cart batteries in parallel (or do I have that backwards?) to create a 12v system. There will no be a tie-in to a vehicle battery; this is essentially a stand-alone system to be housed in our short-bus RV.

1. The panel has 24v output so the first stumbling block is choosing a charge controller.  Math tells me I need a controller that can handle at least 10 amps - is there a suitably-sized MPPT controller in the $100-200 range that will automatically drop the voltage to 12 volts, removing the need for a transformer in there? 

2. Our overall 110V needs are quite modest (charging ability for laptop and GPS, maybe occasional use of a DVD player & small flatscreen TV) so a smaller inverter should be fine - is 600 watts too small?

Thanks in advance for any/all help... I get a little lost going much beyond V=IR. 
« Last Edit: Apr 22, 2011 07:39 pm by Ann Guentert »
220 Posts
Apr 24, 2011 02:03 am
Re: New to solar, starting with a BP SX170B 24v panel...what next?

Hi Ann,

we added a few scribbles to one of the altE store rv kit line drawings to get us started.

a look at some of the goodies

SS15 controller

baby box enclosure

10 amp breaker

20 amp breaker

don't see why a 600watt inverter won't meet your needs for what you have listed. might even have room in the breaker box for a 63 amp breaker (largest size available) almost close enough for a 600 watt inverter..70a would be better.

not seeing any first generation mc cable extensions available? bet they can still get you one. we get a long cable with the mc plugs and cut it in half. the plugs go to our pv module and the cut ends are used for the wire run to the breaker/controller.

cheers for now,
3 Posts
Apr 24, 2011 12:30 pm
Re: New to solar, starting with a BP SX170B 24v panel...what next?

A nice schematic and everything -thanks for making this easy, Dave! 

I do have a few more of the quick-connectors like those on the panel leads so I can easily make some custom extensions.
My budget for the whole system is ~$1K...with the panel purchase, your suggestions and some other goodies, I've got a couple hundred bucks left for the inverter. Is there any advantage of one of these over the other?

Go Power SW 300

Samlex PST 30S 12A
« Last Edit: Apr 24, 2011 12:59 pm by Ann Guentert »
220 Posts
Apr 25, 2011 01:58 am
Re: New to solar, starting with a BP SX170B 24v panel...what next?

 Hi again Ann,

i'm perhaps a bit jaded in my opinion here as i have some of the samlex/cotek products and love them.

only issue i see with the PST 30S is the set screw connections used for the DC input..easily solved with 29 cent ferrules or by filling the end of the wire in with solder.

some good info in the product reviews...manufactures should be aware that gone are the days of giving bad service and only have to worry about the customer telling his neighbors and coworkers..with this new fangled interwebie thing everyone will know...forever!

kind regards, dave
3 Posts
Apr 25, 2011 02:25 pm
Re: New to solar, starting with a BP SX170B 24v panel...what next?

Thanks again, Dave - I think I'm finally ready to shop and build.  Smiley

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