Solar thread, questions, pictures, and help.

[TucsonAZ]

I have spent a COPIOUS amount of time on solar the past few months, I'm no expert but I would really love to be able to help others thinking of going down that path. If you have any questions, are thinking of going solar and need advice or you want to share your solar build, let's do it here so that we can all gain something from it.

I've found there to be A LOT of false information out there and would really love to help others get their solar project done right the first time.

 

[Zil]

how about a quick outline of what you used and how you did it?

 

[Toes]

Would definitely love to see a rundown of your setup. Maybe with accompanying comments and explanations?

 

[TucsonAZ]

I went with six Solarworld 230 watt panels, they were the best value I could find at $0.69 a watt. I used a MidNite Classic 150 charge controller which was $440 shipped via the big auction site. A Cotek 1,500 watt 24v pure sine wave inverter which was $220 shipped from ABC electronics. CBI QY DC breakers, rated for 125v (same as the MidNite breakers) which were $50 shipped for a box of 12 at 15a each, purchased from the same auction site. And four 125ah AGM batteries, they're old pulls from a UPS but will work for now and were only $60 each.

This was the absolute best value I could find in the wattage I am needing to be with the ability to expand in the future.

 

[Zil]

You have to match the voltage across the system. Volt output of the solar to volt input to the charge controller. Volt output from the controller to voltage of the battery bank. Voltage of the battery bank to volt in to the inverter. You have a 24 volt battery bank?

 

[psytechguy]

Not if you use an MPPT controller. They'll let you use high voltage panels and down convert to 12 volts if that's the system you're running.

I run 30 volt Sharp 230 watt panels into my 12 volt system using a Morningstar MPPT controller.

 

[Mac J]

With the knowledge that running down a 6volt or a 12volt battery below 50% is harmful enough to shorten the life of the battery, is there a way, other than visually looking at a controller and shutting the system down manually, that the battery power will shut off at a set percentage?
In other words: Suppose that on a cloudy or rainy spell the batteries could not boost up via the solar panels, could the batteries be set to "turn off" when the percentage lowers beyond 55% or so (so as not to shorten battery life)?

 

[Zil]

"A Cotek 1,500 watt 24v pure sine wave inverter" will not work on a 12 volt battery.

 

[blars]

There are devices to shut off power under low battery conditions. Don't expect to find cheap and good at the same time. Voltage sensing ones are relitivly cheap, but voltage is not a reliable state of charge indicator other than on a battery that has not had any load or charge for an hour or so. Good ones will log the amp-hours used and charged, and will let you know what your battery condition is.

 

[Mac J]

Thank you blars,
I'm waiting for TucsonAZ to get back to this thread. I'm hoping he can give parts and prices of various controllers, meters, shunts, battery monitors and the shut off switchs you mentioned.

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it would also be most helpful if he could provide a copy of a schematic if available.

 

[AimlessWanderLust]

Not if you use an MPPT controller. They'll let you use high voltage panels and down convert to 12 volts if that's the system you're running.

I run 30 volt Sharp 230 watt panels into my 12 volt system using a Morningstar MPPT controller.

Not all MPPT controllers can handle this. There is still an upper and lower limit of the voltage swing the controller can handle. Case in point, we had an MPPT controller capable of 500 watts, but would only support 12V in and 12V out. It's best to check the abilities of any and all devices you plan to use, instead of assuming blanket statements!

 

[Mac J]

Thank you blars,
I'm waiting for TucsonAZ to get back to this thread. I'm hoping he can give parts and prices of various controllers, meters, shunts, battery monitors and the shut off switchs you mentioned.

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it would also be most helpful if he could provide a copy of a schematic if available.

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http://www.pbase.com/mainecruising/battery_monitor&page=1

This is what I was looking for.

 

[akrvbob]

Very good point that not all MPPT controllers will handle high voltages. Fact is most older ones won't. with Blue Sky controllers only the ones with HV in their name are designed for very high voltages.

Cheap panels are designed for houses and are used in huge arrays meaning they have very long runs. They need higher voltages to keep the cable size down.
Bob

 

[TucsonAZ]

As a rule you want to go one step off, so if you're running a 12v battery bank going 24v into the charge controller is wise, with a 24v bank 48v to the charge controller (I would skip over 36v) works well. You may be able to go 72v from your panels to a 12v system but I would only suggest this if you have a 200 foot wire run between the panels and charge controller. There are some exceptions with everything of course, my panels for example have a VMP under 30v so I wouldn't want to run a 24v system off of them hence running them in banks of 2 which gives me the higher voltage.

Remember, in the world of solar, go cheap on the panels and spend the money needed on the other items like the charge controller. I went with a Midnite Classic 150 because of my voltage/amperage, if I were going smaller I would have much rather gotten a Rouge charge controller, awesome MPPT for the money. Any MPPT controller you see under $200 is most likely a lie and is just a PWM controller.

At about 400w you reach a point where it becomes more cost effective to purchase the grid tie panels (24v) versus the 12v panels and use the money you're saving on the MPPT charge controller. Solar at 12v works but is really less than ideal, so I would say to step up to 24v systems at about the 400w mark or at the very least step up to 24v panels and a 6v batteries in series.

Sorry for the delays, this project I'm working on has been intense!

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This is what my roof looks like right after getting the panels up there, I now have them wired into the combiner box inside so each of the three strings in on a breaker which is more there to act as a switch than an actual breaker. That allows me to keep 4 panels (two strings) in service should some issue come up with one or two other panels.

 

[Fearnoevil]

Hey Tucson, thanks for starting this thread! Although I know I'm far from the point where I'll need to build my system (6-8 months maybe) I do want to get all the important systems designed so that I can set aside the appropriate space and also incorporate the necessary wiring runs, etc. prior to beginning my mod. Also I'd like to get a handle on what it's going to cost.

From your first post, it looks like you've got at least $2k into yours, which is depressing to me, lol, cuz I was hoping to be able to build mine for less than half that . So my big hurdle is trying to figure out how much juice I'm going to need and then figure out how to design a system that'll support it. Yah, there's a hundred ways to go, but basically I'd like to rely mostly on solar and have a small 1600 watt genset for backup. Not planning on using much power, 6cu ft 150w fridge, 5K w ac, 11k w microwave, a small 45w LED TV and some lights, although I would like to occasionally run a small washer and dryer (1400 & 800 watts). So as a guesstimate my peak usage should be no more than say 6500w :huh: So how would I size my battery storage bank and solar panel needs, roughly ;?D

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My initial plan was 400w of solar panels and 6 - 12v deep cycle (used/refurbished) batteries and a 2kw invertor, does that sound like it's in the ballpark?

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Oh yeah and as for the inverter, I know zip about that subject as well, but if I'm 6500w peak usage, then do I need an equivalent sized inverter? I know some stuff could run on dc, but not the washer, dryer, microwave and fridge (not currently planning on using an RV fridge due to cost and efficiency), but I could adjust so that nothing major would be running at laundry time ;?D

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And AC off when running anything else at all, lol.

 

[TucsonAZ]

Hey Tucson, thanks for starting this thread! Although I know I'm far from the point where I'll need to build my system (6-8 months maybe) I do want to get all the important systems designed so that I can set aside the appropriate space and also incorporate the necessary wiring runs, etc. prior to beginning my mod. Also I'd like to get a handle on what it's going to cost.

From your first post, it looks like you've got at least $2k into yours, which is depressing to me, lol, cuz I was hoping to be able to build mine for less than half that . So my big hurdle is trying to figure out how much juice I'm going to need and then figure out how to design a system that'll support it. Yah, there's a hundred ways to go, but basically I'd like to rely mostly on solar and have a small 1600 watt genset for backup. Not planning on using much power, 6cu ft 150w fridge, 5K w ac, 11k w microwave, a small 45w LED TV and some lights, although I would like to occasionally run a small washer and dryer (1400 & 800 watts). So as a guesstimate my peak usage should be no more than say 6500w :huh: So how would I size my battery storage bank and solar panel needs, roughly ;?D

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My initial plan was 400w of solar panels and 6 - 12v deep cycle (used/refurbished) batteries and a 2kw invertor, does that sound like it's in the ballpark?

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Oh yeah and as for the inverter, I know zip about that subject as well, but if I'm 6500w peak usage, then do I need an equivalent sized inverter? I know some stuff could run on dc, but not the washer, dryer, microwave and fridge (not currently planning on using an RV fridge due to cost and efficiency), but I could adjust so that nothing major would be running at laundry time ;?D

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And AC off when running anything else at all, lol.

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Well, the bad news is you are not going to be able to make s system like that work, not with AC, fridge and other needs, you will be using so much power that there isn't a roof in a mobile application that would fit the solar panels needed and certainly not 400w of solar panels for a system like that.

Factor in 52% efficiency (that's the rule of thumb)so at best, on a clear day in a sunny location 400w of panels will get you 1,100 watts put back in your bank.

Start by figuring out what you can get away with not using. The AC alone could devour the 6,000 watts in a day, AC and solar just won't work so figure out another option. Start with buying a Kill-O-Watt and seeing what you're using, you'll be surprised by what some seemingly small things suck up.

Don't get discouraged, just know that solar means a lifestyle change, a different way of seeing your power, like water in a desert not at the beach. Be realistic and work on conserving, then design your system.

Also, for a larger system, plan on at least a 24v battery bank, you'll be much, much happier!

 

[highdesertranger]

fearnoevil not trying to talk smack here but you say 6500 watts is not a lot. that's a huge amount you could run a house off that. you know there are other options. 12v tv is one. hang your clothes to dry(solar dryer). wash your clothes with a hand washer couple of options here. you say no to 12v frig, why cost? a 12v compressor frig is much more efficient than a 120v run though an invertor(believe I have tried the 120v). as has been pointed out on other threads you will be ahead to just bite the bullet and go 12v with the frig it will be cheaper in the long run. I myself have no use for a microwave or ac. get rid of those and you could cut your power consumption by a factor of ten at least. or you could just run a generator when you want to use the ac and micro. highdesertranger

 

[TucsonAZ]

fearnoevil not trying to talk smack here but you say 6500 watts is not a lot. that's a huge amount you could run a house off that. you know there are other options. 12v tv is one. hang your clothes to dry(solar dryer). wash your clothes with a hand washer couple of options here. you say no to 12v frig, why cost? a 12v compressor frig is much more efficient than a 120v run though an invertor(believe I have tried the 120v). as has been pointed out on other threads you will be ahead to just bite the bullet and go 12v with the frig it will be cheaper in the long run. I myself have no use for a microwave or ac. get rid of those and you could cut your power consumption by a factor of ten at least. or you could just run a generator when you want to use the ac and micro. highdesertranger

If you quantify this with watts, you will find that all things being equal often times the 12v items use more power. In the case of a 12v fridge even if less "efficient" than an Energy Star 120v unit they use less power because they're sized appropriate to the need or use.

I want to be able to store ice while on the road and have my 120v chest freezer going via my solar/inverter right now, it's 10 degrees inside, 60 pounds of ice in the unit along with some food and such. It has used 100 watts in the last 5 hours which is very acceptable to me.

 

[Fearnoevil]

Well that's something I'm still trying to get my head around. So a question, if I'm only planning on hitting that peak of 6500w for brief periods, say an hour or two at the most, will having a lot more batteries help, say 12 or 18 instead of 6? And also increasing my solar panels to say 800 - 900w? As I see it, hopefully I won't be spending the majority of my time indoors most days, so say the juice only gets used for an hour in the am, then 3-4 hrs in the pm, but most of that is just a couple of lights, a fan instead of ac whenever possible (I don't plan on spending a lot of time in hot climes in the summer months, not my preference) and either the tv or puter. Peak usage like microwaves or hotplates only for very short cycles, the washer and dryer once a week, and if needed I can turn everything else off then. Does that make a difference, can it be juggled somehow yet still practical??
Yeah, there's just so many gaps in mah lerning, sheesh.

Highdesert, I read somewhere on another forum that there are comparable sized compressor fridges that are, of course, way cheaper up front, and run quite a bit more cheaply then rv fridges which is why I just did a quick search of a 7.3 cu ft fridge/freezer and pulled the watts from that. There may be more efficient ones, idk, plus I've heard you can improve efficiency by adding insulation and venting the heat with fans, still an area I'm self-educating myself in for sure

And sorry, no handwashing for me, if I have to plug in once a week to shore power to do laundry, then so be it, but I'm not into that kind of make work. It's like mowing lawns, as a homeowner it's necessary, but I HATE it, never been the lawn-proud type, it's just tedious imo and when I finally cut free from my current moorings, I'd prefer to keep that stuff to a minimum so it's one "luxury" I'd like to keep. I will hand wash dishes tho, how's that for a compromise . Hanging laundry to dry is an option - I'm trying to work out a sort of wind-powered tumble-dryer - it'll sit on my back porch and look sort of like a really big bingo-ball cage, except it'll be on its side and have little fins that stick out and catch the air as I cruise down the road, spinning and air drying my clothes, easy peasy

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Oops, I made a big mistake in my calculations, lol, and put Btu's in place of watts for my AC, lol, so drop that 6500w by 4000w, so about 2500w peak, sheesh. :dodgy:

 

[highdesertranger]

well that's a big difference. 2500 watts is almost doable. although still a lot off of solar. have you thought about how much 12 or 18 batteries weigh. and what about the water to run a washing machine. just a suggestion but maybe I would try to do a little more of a minimalist approach, if it was me anyways. of course I am not a rich man, so I always look at the minimalist side, hell I drive a 36 year old vehicle. highdesertranger