Advice to make a 155w solar setup closer to 500watts

[wopachop]

My toyhauler came with a 155watt panel, 30amp GoPower pwm controller and they ran 10awg wire to the batteries that are roughly 20 feet away as the mouse flies. 

At first i thought i would simply add another panel or 2 in parallel and run thicker wire. Get close to the solar controllers max rating of 500watts. 

I briefly read about mix matched panels. To my surprise the one article i read was saying its better to run them in series. Even better approach is to use multiple solar controllers if you have different panels. 

Now im wondering if its best to leave the current setup alone. Then add new panels and a new controller. Negative to that is added costs. Was hoping to get 500watts as cheap as possible. I would like to buy quality wire though so i can upgrade to even more solar down the road. 

I tested my panel years ago and remember it being somewhere in the 18v range. Not at the trailer to test it again. I was reading that will be a big factor in trying to decide what additional panels to buy. 

Ive been thinking about using a separate starting battery for my genny. So if i did have 2 solar controllers i could use my smaller 155watt panel to keep my genny starting battery topped off. Problem for me is waking up in glamis with very low batteries. Sun isnt producing solar yet. I hate putting that big generator load on the depleted pair of 6volts. I have older spare 12v starting/hybrid marine batteries that would be great to use for the genny only. I could then deplete my 6volts a little more than youre supposed to at night.

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So the main questions are:

1. Any cool online stores that have quality wire for decent prices?

2. Do i need to know my exact solar panel voltage before people can help advise on additional panels to buy or what approach will be most efficient? (just remember im a cheapo trying to get to 500watt for now.......once my 6volts die i will go to lithium batteries, big inverter and more solar.....so im kind of hoping whatever panel i buy now will also work down the road)

 

[DTA]

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[Dockmaster]

Never a good idea to mix-n-match panels of different make, size and vintage. Why do you need to replace the 10awg wire? Something wrong with it? 10awg is plenty big enough to handle 500 watts and then some. If it were me, I would get new panels, run them in series and upgrade to a better charge controller. Running the panels in series at higher voltage is much more efficient. I have a large solar setup at my off grid cabin. I have 315 watt panels run in series in groups of 3 (12 panels total). It's a 48v system. Each group of panels (945 watts total) is wired with 10awg and the wire run is from the roof of my shop down to my controller, easily a 50' run. 

 

[kazuaki]

I'm not an expert, but have been learning and installed a system on my fifth wheel this summer. A couple things to consider...while series will generate higher voltage and work better without huge wiring, it is also more susceptible to shading issues.  If one panel gets some shade on it (from a AC unit, antenna, sat dish), the output of all panels will be reduced.  If you are able to place your panels in such a way that they never get shaded, this isn't an issue. Also, solar charge controllers will be limited by how much input voltage they can handle.  Some panels have voltages as high as 65V, so two panels in series would already be more than a 100V rated controller could handle.  With a system of 500W it may not be as much of an issue. I learned a fair amount in the process, so let me know if you need any more info. There are also several members with extensive knowledge in this area.

 

[Punchdrunk Monkey]

I just bought a solar package from @Lord of the Dunes. The price was good and the package was complete. I had a few issues while installing and getting the correct settings. LOTD helped the whole way! I was able to text him dumb questions and call him for more tech questions. He always helped. Sometimes he gets a little more technical than I need. As I am admittingly not a electrical guy. But in the end, the system works great!

 

[wopachop]

I suppose a super cheap way to avoid buying wire would be to move the existing solar controller a few feet away from the batteries. Add more panels in series. 

Should have measured the actual wire distance. Also should have looked at the solar controllers manual to see voltage rating. 

As it sits now the batteries never get fully charged. The trailer came with the wfco charger and it never goes over 13.7v. The solar tries to supplement but the 10awg is just thin enough that i never see 14.7v at the batteries. I used to use my expensive RC plane battery charger. Until one morning like a dummy i rinsed the top of the batteries off. Wanted to check their water. Hooked up my charger without drying off the tops. It fried something inside. Its a funny coincidence it broke a good year or two ago. Plan to take it apart this weekend. That charger was sweet because you could adjust amps on the fly. I was able to do really accurate equalization charges. My 6volts are about 3 years old. So maybe in 2 years go lithium and hit up thee Lord to buy whatever is needed. If he is still selling stuff then. Kicking myself for not thinking about moving my solar controller earlier. It didnt hit me until typing on this thread. 

Thanks for all the advice so far!!

 

[DTA]

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[wopachop]

It seems odd that your batteries never fully charge.

This makes for a tricky topic. You are both right and wrong at the same time. Lets pretend your car had a 20 gallon gas tank but for whatever reason you always filled it up to 19 gallons. Did this for 10 years as your daily driver to work. It traveled fine. You never ran outta gas. Never late to work. 

Charging batteries is similar. Its kind of hard getting a battery to true 100% unless you have a fancy setup with temperature compensation. Gets worse in the winter because you should be charging at a higher voltage to get the same results. 

Technology has really caught up in the RV world with newer inverter/chargers and solar becoming popular. My friend has an 02 warrior. It has the dreaded wfco charger. I dont think its ever gone into 14.4volt mode. The multiple batteries over the years have never ever ever been even close to fully charged. Yet its gone camping in glamis for 20 years and the people inside never really knew. Dont really matter. What matters is they had fun camping together as a family. It just comes down to money. Which also gets tricky. If you can afford new batteries you likely have a charging setup that maintains them better and gives better longevity and value. Where if you go paycheck to paycheck, you likely have a crappy charging setup, which means you will need new batteries sooner. 

 

[Kraut_n_Rice]

A fully charged "12 volt" battery is 12.6 volts.  Where are your other numbers coming from?  Is that the float setting on your charge controller?

If you are taking your batteries down to 3.4 volt, you are killing them

 

[Squatcher]

I suppose a super cheap way to avoid buying wire would be to move the existing solar controller a few feet away from the batteries. Add more panels in series. 

Should have measured the actual wire distance. Also should have looked at the solar controllers manual to see voltage rating. 

As it sits now the batteries never get fully charged. The trailer came with the wfco charger and it never goes over 13.7v. The solar tries to supplement but the 10awg is just thin enough that i never see 14.7v at the batteries. I used to use my expensive RC plane battery charger. Until one morning like a dummy i rinsed the top of the batteries off. Wanted to check their water. Hooked up my charger without drying off the tops. It fried something inside. Its a funny coincidence it broke a good year or two ago. Plan to take it apart this weekend. That charger was sweet because you could adjust amps on the fly. I was able to do really accurate equalization charges. My 6volts are about 3 years old. So maybe in 2 years go lithium and hit up thee Lord to buy whatever is needed. If he is still selling stuff then. Kicking myself for not thinking about moving my solar controller earlier. It didnt hit me until typing on this thread. 

Thanks for all the advice so far!!

don't add in series with that controller.  I think you are limited with that controller to the same voltage panel and Don't run in Series.  It won't handle the higher voltage.

 

[Squatcher]

A fully charged "12 volt" battery is 12.6 volts.  Where are your other numbers coming from?  Is that the float setting on your charge controller?

If you are taking your batteries down to 3.4 volt, you are killing them

depends on the battery,  AGM is 13 volts, wet is 12.6 and my lipo never get below 13 volt and float charge at 14.8 I think 13.8 in the full charge but they are measure in amount of load left not voltage.

 

[wopachop]

A fully charged "12 volt" battery is 12.6 volts.  Where are your other numbers coming from?  Is that the float setting on your charge controller?

I usually reference the Trojan guide. Other brands are slightly different. This is kind of old news because i think it would be a mistake buying flooded golf cart batteries in  2022. I would almost go with a 100ah single Lithium over the dual 6volts i have now at around 220ah. They are similar because of how far you can drain each safely. I bet the lithium would sag less under a quick but heavy inverter load as well. 

Trojan guide pdf

edit: i didnt answer the question. its the charging voltage of different batteries at different stages. 

 

[wopachop]

The approach to boondocking has changed a bit i think. In the past people would run the genny and get to 90% charge. Then shut it down because its not worth wasting the gasoline it takes to taper down the amps and get the battery closer to 100%. You got a giant 5000watt genny trying to gently push the final amps in. (people who went the 2000watt honda route were smart)

Solar changed that because now the sun can handle the low amp finishing charge. 

 

[Lord of the Dunes]

I'll throw my .0005 cents in.

1. The solar panel is only 155w. They only produce 75-80% of rated power, so 116w - 124w actual output.

2. It's a Go Power. That's like the Yugo of the solar industry. Also it's a PWM, so it's using a chopper circuit to reduce 18v down to about 13v, so during the time the circuit is off, the power produced by the panel is lost. So let's assume the PV input is 120w, the PWM is losing 27% of that due to being a POS so max output of this setup is 86.7w. That's under perfect sun, no shade from anything on the roof and no wire loss. Of course we all know the sun's output varies even if the sky is clear and there are always line losses.

3. Flooded lead-acid batteries lose 20% of the power used to charge them just because of the chemistry. Assuming perfect connections at the terminals and the batteries are brand new, we now have a max. of 69.33w charging the batteries. That is the same amount of power my laptop uses in power saving mode and the same amount of power my cell phone uses to charge itself, in case anyone was wondering how little 69 w is.

4. A lot of inverters lose 25w - 40w just sitting there idling, with no load. In case you do have an inverter hooked up to your batteries.

5. 2 x 6v 220Ah batteries equals 110Ah of usable power (100% down to 50%.) That's 110Ah x 12.3v nominal = 1353 wh. Since lead acid tapers down charging current for the last 20% of charge, most people's FLA batteries don't usually get charged above 80% or so.

6. At 69wh into the batteries, it would take 19.6 hrs to charge those batteries up from 50% (12.0v) to 100% (12.6v at rest). Since we only get about 7-8 good hrs of sun per day, let's call it 7.5 hrs. You're only getting about 38% of the daily power you need to recharge the batteries, assuming you used 1353 wh of power in a 24 hr period. You might not use that much, but even still, you're not getting anywhere near 155w out of that setup.

Recommendations. Toss the 155w panel and Go Power PWM controller. Considering how inefficient that type of panel (18v, commonly called a 12v panel) is and how much power the PWM controller is wasting, you have better things to do with that roof space than get a measly 86 or 87w out of it. I like Sunpower panels since they're the most efficient at 20% compared to older panels like that at about 14% efficiency. Always use a good quality MPPT controller, no sense in throwing away 25 -30% of your PV power.

Or if you have a small spot that panel fits nicely in, get an MPPT controller for it and you can get about 120w out of it. Get more panels, either 1 300w panel or 2 300w panels and add those to the roof with a good MPPT controller. This way they can power all of your bilge fans and odd 12v accessories all day and charge these batteries or future LFP batteries at the same time.

What I did was bought a 45 lb ice machine and I run it from breakfast to sunset and it runs off the inverter powered only by solar and the battery bank was full at the end of the day, plus 20 lbs of free ice per day.

 

[wopachop]

Are you using the Ice machine as your fridge? I got a little lost on that last part. I heard people turn top loading freezers into very efficient refrigerators. (it might have even been lotd who posted that a year ago)

I have a mini dorm room fridge. Sucker only uses 70w compared to my absorption fridge that is around 350w and also stays running much much longer. Thinking this winter bring the mini fridge into the trailer. It should help to heat the trailer slightly too. Could put items i use daily in the mini fridge. Keep the absorption fridge on propane and try to keep the door shut. 

Real life scenario the 155w panel only puts 8amps to the batteries. 

edit: his ice maker is making ice so it cant also be turned down to fridge temps. that was dumb. 

 

[wopachop]

Its a funny coincidence it broke a good year or two ago. Plan to take it apart this weekend.

Took it apart. Looked around. Plugged it in and now its working. 

Swear the thing was giving me an error code. I thought i shorted and fried something inside.

It looks like a fisher price toy. Its actually a $300 charger. Highly programmable. Ive done crazy stuff with it. Had a golf cart with dead batteries. I would hook up this charger in a way its like an older "dumb" charger. It doesnt care the voltage. No safety shutoffs. It supplies the amps you tell it and doesnt stop. Was able to salvage some super dead 8v golf cart batteries.

I think i took a good battery and jumper cables. Hooked to the bad battery and then started the charge. Once the charger began running i would remove the cables. The battery was so dead the charger was having trouble recognizing that it was hooked to a battery. So its still kind of smart. But has so many programs you can make it a stupid charger. 

 

[wopachop]

Sorry my phone camera blows. Hurts my head looking at blurry pics. I better not jinx myself....ive been waiting for it to die for years. Even removed the hard cover and left the soft silicone only. I used to play soccer and hacky sack so every time it drops im able to catch it with my foot and lessen the blow. Happens so quick i dont even realize. I also let out a scream so i dont hear the damage. While that cant help, it sure seems to easy the pain mentally!! 

 

[Lord of the Dunes]

Are you using the Ice machine as your fridge? I got a little lost on that last part. I heard people turn top loading freezers into very efficient refrigerators. (it might have even been lotd who posted that a year ago)

I have a mini dorm room fridge. Sucker only uses 70w compared to my absorption fridge that is around 350w and also stays running much much longer. Thinking this winter bring the mini fridge into the trailer. It should help to heat the trailer slightly too. Could put items i use daily in the mini fridge. Keep the absorption fridge on propane and try to keep the door shut. 

Real life scenario the 155w panel only puts 8amps to the batteries. 

edit: his ice maker is making ice so it cant also be turned down to fridge temps. that was dumb. 

No, sorry I wasn't clear. This is on my old solar setup. I had 6 x 6v batteries and the solar panels would have the batteries fully charged and in float mode by 9:45 or 10 am. I didn't like that, because when the system is in float mode, it's not getting any solar power, it's just sitting there. So I added the ice maker to use more power during the day and make 20 lb of free ice per day. I keep 2 ice chests in the back - one full of beer, one full of soda and mixers. The ice keeps those topped off, plus ice for cocktails, and keeping the drinks in the coolers allows me to keep only food in the fridge, which drastically cuts down on fridge traffic, keeping the fridge colder on average.

 

[Lord of the Dunes]

70w for a mini fridge is pretty inefficient. I also have 2 Rovsun 54 qt 12/24 chest type fridges. They only use 43w when running and they run about 15 - 20 min. per hour. I ran both of them off of a 200A LFP "camping battery" for over 5 days with no recharging.

A couple things I like about chest type fridges is when you open the lid, you don't lose all of the cold air like a front door fridge or mini fridge. The other thing is they advertise they can go down to -14*, but when I used an IR thermometer to check, the lower section was at about -30* and if I set the temp to about 20* or so, the lower area is at about -4* (great for ice cream and frozen stuff) and the upper area is down around 24*, which is great for food and beer. My plan is to use these to replace the indoor ice chests and use them for long road trips in the car or car camping/glamping trips.