Yes, I said that right. 56 30-watt solar panels.

[GrantRobertson]

Originally Posted by nat_ster

Why 4 inverters, VS one larger good one?

Four separate inverters also let you turn on only the ones you need. Inverters use power just sitting there, when on.

[charles_m]

i would have to imagine, though, that the parasitic draw of 1 big inverter is less than 4

my inverter has load-sensing and only turns on when power is needed.

[GrantRobertson]

Originally Posted by charles_m

i would have to imagine, though, that the parasitic draw of 1 big inverter is less than 4

my inverter has load-sensing and only turns on when power is needed.

True, if you need all of them all the time. But if you can cut it down to just one or two most of the time, you will save power in the long run.

Hey, which model of inverter is that? I want to look into those. With the right design you could be running only one inverter most of the time but without the inconvenience of turning them on and off all the time.

Thanks

[charles_m]

its a tripplie aps2424
it's not pure sine wave, though.

i still would say that a small inverter and a big inverter have roughly the same draw, even when not supplying a load. the only difference being that if you have 4 small ones and they are all on, they are all also drawing whatever parasitic drain they would be as well.

and, thinking about it, if parasitic draw of your inverter is (proportionally) large enough to be worrying about, your system probably isnt going to be big enough to meet your needs.

just my .02 though, and of course im sure my goals are different from someone elses. i just know that i sized my system the way i did precisely because i didn't want to have to be on a wattage diet and count my watts used everyday. i just wanted to live and use power at will. that meant sizing things up and leaving room to easily expand. this means adaptable charge controllers that can handle a range of voltages and currents, rooftop combiner boxes, and thick cables everywhere with a breaker on every wire run for safety. so far so good, and i might even add two more 300 watt panels to bring the total up to 1800 watts. the nice thing is, at this point, that would only cost me $450 cause i can get 300 watt panels for $225 a piece

[GrantRobertson]

Originally Posted by charles_m

its a tripplie aps2424


i might even add two more 300 watt panels to bring the total up to 1800 watts. the nice thing is, at this point, that would only cost me $450 cause i can get 300 watt panels for $225 a piece

Yeah, I'm planning for what will fit on a much smaller roof.

BTW, what are the dimensions of those 300 watt panels? Where are you getting them?

Also, check your PMs. I left you a message about buying a shuttle bus.

[charles_m]

the 300 watt panels im using are about 39x78" run them lengthwise across my bus. figure 40" of length for each panel. I get them from a wholesale installer i met out here who hooks me up with good deals on panels, cc's racking, and cables

with 16' of roof you could easily run 4 panels for 1200 watts

I saw your message--the only short buses i have have the lifts in them and are triton v10 gas engines. probably not what you're looking for

[Big11beard]

Originally Posted by charles_m

so do those panels have a cover over them? i see some kind of rounded plastic looking thing. If that's the case, that must wreak havoc on their output--I have 1200 watts of panels, and the highest output ive ever seen them give me is around 900 watts. if there is any dirt/debris on them, the power drops quickly--id do some testing and see how much power you're actually getting out of those panels. you might want to try and find a way to replace that cover if you can.

Yes the panels down the center do have hard acrylic covers on them strong enough to walk on. They are also in a steal frame. These panels came from work and these low performance panels work really well in scattered light. It is about the only advantage of a 20"x26" panel at 30 watts. I am sure that the power will diminished but my panels facing away from the sun will produce less. from the front the panels will look like this. /-\. 2 of the 6 panels in the series string will always be facing away from the sun. I'll be sure to report back here again when it is up and running.

I do know how to remove the panels from the housing and will for 12 of the panels down the side. The reality is that this is probably way more power then I will use anyway on the bus. We live off grid in Nicaragua and we were living on a very modest 2 x 230 watt and 2 x Trojan T105. The bus serves us as a vehicle to hall a house worth of used goods back to Nica while avoiding import tax of 30% - 100%.

This array is rated at 1860 Watts. I am expecting 1000 - 1200 Watts per hour for 6 hours. Somewhere around 7kW/hrs

[Big11beard]

Originally Posted by charles_m

Im also running a midnite cc and 8x t105 batteries with a 24v inverter. its an awesome setup and it runs everything i need easily. i never worry about my power and i can even run my welder for short periods of time!

I can't tell you how excited I am to hear that you can run a welder for a short time!!! What are the specs for your welder? I would love to hall on back and be prepared an small repairs along the way.

[Big11beard]

Originally Posted by charles_m

do you have plans for a breaker box of some kind? how are you combining your solar panels? I used a rooftop combiner box and a dc load box with 175 amp breaker.

also, have you picked out your battery cables yet?? that's an expensive item that you don't want to skimp on.

I'll have photos a little later with the wiring I did. I couldn't bring myself to pay for a breaker box. $100+ for the box plus $15 per breaker +... adds up quick.

I dropped 9 lines of 14AWG zip wire all the way to the wheel well. Here I have each 72V line going to a 15A switch and a 4A glass Fuse. After the fuse each line stacks on a insulated Bus Bar.

This setup is roughly 10% of the cost of a breaker box.

[bansil]

cool project and I like the idea of 4 smaller systems at the farm...good thinking

[Big11beard]

Originally Posted by charles_m

also, have you picked out your battery cables yet?? that's an expensive item that you don't want to skimp on.

Battery Cables: The bus at some point had a handicap lift in the back which had an Heavy power cable running the full length of the bus. While the lift was removed the cable is still there. I think it may be 0AWG but the the text is rubbed off the cable. I haven't pulled it all the way out yet but I figured I could use it to make my battery bank cables.

[Big11beard]

Originally Posted by GrantRobertson

True, if you need all of them all the time. But if you can cut it down to just one or two most of the time, you will save power in the long run.

Hey, which model of inverter is that? I want to look into those. With the right design you could be running only one inverter most of the time but without the inconvenience of turning them on and off all the time.

Thanks

The Chinese inverter I am looking at is on Ebay.

8000w 32000W LF Split Phase Pure Sine Power Inverter DC24V AC220V 110V 60Hz | eBay

[family wagon]

Originally Posted by charles_m

great idea about running 12v loads in series to make 24v--ive been looking at 24->12v step down converters

Keep in mind the two 12v loads have to be exactly equal in their power consumption, or the voltage won't split evenly. It works easily for sets of incandescent lamps or LEDs. It could be tricky for other things.. water pumps whose power draw varies according to the water flow, etc.

[charles_m]

The welder I use is a Hobart Handler 140--longest I've used it is about maybe 5 minutes of actual welding time. The modsine inverter might have made it not perform perfectly, but I could hardly tell and I had great luck welding 1/8" pieces of 2" flat bar and agle iron. Used about 8% of my battery. The trick is having enough cells to distribute the load and thick enough wires to keep the voltage drop low enough so it doesnt make the inverter think you're out of juice and cut off. I used 0000 gauge wire from the batteries to the breaker (15') and then 00 gauge from the breaker to the inverter (3') with 00 gauge to interconnect the batteries. I also run a 2000 watt electric water heater for about 20-30 mins a day if it's sunny to heat my hot water. Never had a problem

I love your ingenuity, I wish I coulda had some free panels from my work! Best of luck out there. These are my fav projects in building a skoolie. Way more fun than grouting tiles :0

[Big11beard]

Side rows going up

[Big11beard]

1" conduit bringing 10 14AWG zip cables into the bus.

[Big11beard]

My Pallet Breaker Box

15Amp switches with 4 Amp glass fuse.

[EastCoastCB]

Originally Posted by charles_m

The welder I use is a Hobart Handler 140--longest I've used it is about maybe 5 minutes of actual welding time. The modsine inverter might have made it not perform perfectly, but I could hardly tell and I had great luck welding 1/8" pieces of 2" flat bar and agle iron. Used about 8% of my battery. The trick is having enough cells to distribute the load and thick enough wires to keep the voltage drop low enough so it doesnt make the inverter think you're out of juice and cut off. I used 0000 gauge wire from the batteries to the breaker (15') and then 00 gauge from the breaker to the inverter (3') with 00 gauge to interconnect the batteries. I also run a 2000 watt electric water heater for about 20-30 mins a day if it's sunny to heat my hot water. Never had a problem

I love your ingenuity, I wish I coulda had some free panels from my work! Best of luck out there. These are my fav projects in building a skoolie. Way more fun than grouting tiles :0

I love the Hobart 140. Easy to use, and easy to power.

[Big11beard]

My feet while standing on top of the center row solar panels. Scary.

[GrantRobertson]

Originally Posted by charles_m

the 300 watt panels im using are about 39x78" run them lengthwise across my bus. figure 40" of length for each panel. I get them from a wholesale installer i met out here who hooks me up with good deals on panels, cc's racking, and cables

with 16' of roof you could easily run 4 panels for 1200 watts

I saw your message--the only short buses i have have the lifts in them and are triton v10 gas engines. probably not what you're looking for

Wow! 1200 watts would be awesome. It would be well over my average expected usage, so my batteries would last a good long time.

You are correct, I would not want those shuttles. Thanks.