Help figuring out solar requirements offgrid

[vyserage]

As title says, i could really use some help! Anybody out there completely versed in solar and electricity?
My lights are 12x panels of qb132 using 600watts max usually, but i can pump them up to 900watts via adjusting the pots. I plan to double down eventually which would make it 1200 watts(600w for both sets of lights)so lets say i need 2000 watts of power per 18 hrs, max.

Im confused about how many watts i need on solar panels, like i see a diy kit for 1000w but i dont know how to factor in power drain when the sun isnt up, so not only do the panels have to power my lights but also provide additional power to charge batteries and prepare for the night. Its all beyond me haha. I'm trying to find the best cheapest deal. I need/want it compeltely off-grid so ill just plug my lights directly into it. I figure i can build the frame or something to hold panels in the backyard where theres PLENTY of sun and just route an extension cord right into my bedroom window and into the power strip for the lights/extras like fans and airpumps. Please help

i've come across this so far:
"Tiny Home" Off-Grid Solar PV Kit
Kilowatt-Hours =8.4
Output Watts =2000
Price =$3295.00

 

[TorturedSoul]

I don't know anything about such things, but my home's total electrical load is less than 2,000 watts, constantly, for 18 hours even when I average that same gross amount of electricity out over the entire 24-hour day. Which causes me to wonder if, instead of your backyard, you'll end up completely covering the roof of your house in solar panels.

Where you live is going to be a big factor. I don't want to know (and you, likely as not, probably don't want to tell the world in the same conversation in which you've mentioned growing cannabis ), but you'll need to figure out your area's average number of "sun hours" per year.

I just used one of those online solar power calculator webpages, entered a 2,000 watt load for 18 hours per day, then entered my zip code... and it told me that my area's daily average number of sunlight hours... is less than five - and, that if I plan to run such a setup year-round, that I am supposed to deduct an hour-and-a-half from that to account for possible Winter issues. That calculator informed me that I'm looking at requiring 36,000 watt-hours per day - 46,800, "assuming inherent efficiency loss."

It was at that point that I found myself thinking, "This looks like it could end up being very expensive, very quick," lol.

Years ago, when I first started hearing about solar power, I saw a thing on PBS about it, and there were solar panels that "tracked the movement" of the sun throughout the day. In other words, they'd align to be as perpindicular as possible to the sun at all times (during the daylight hours) in order to generate the maximum amount of electricity. I assume that this would help significantly - but would also add significantly to your expenses and the complexity of your setup. Also, if I remember correctly, the panel movement was only along one axis - so, while it would track the sun throughout the day, it couldn't adjust for the varying "path" throughout the year. In regards to that, I assume that one was supposed to initially install the panels so that they would basically give the best yearly average performance. But that is just a guess.

Anyway, since (presumably) you have done me the courtesy of reading my rambling, here are some solar calculator webpages. I hope at least one of them can help you figure out your location's yearly average number of sunlight hours per day, and your (projected) actual panel requirements:

https://www.wholesalesolar.com/solar-information/start-here/offgrid-calculator
https://www.gogreensolar.com/pages/how-many-solar-panels-do-i-need
https://us.sunpower.com/blog/how-many-solar-panels-do-you-need-panel-size-and-output-factors/

One of the comments at the third link mentions that there is still a 30% tax credit available (if you live in the USA). That would offset some of your equipment expenses. And it might provide a little "warm and fuzzy" feeling, lol, knowing that Uncle Sam helped pay for your cannabis-growing operation .

Good luck, and please keep us updated! I'll "step away" now, in hopes that one or more people who use solar electricity-generating devices can help you.

 

[Weaselcracker]

I suspect you can find much better sources of info on the subject than this forum, but you never know. Where I live in the middle of nowhere there are usually one or two local wandering ‘off grid’ ‘’experts’ at any given time, making money off helping people set up solar and wind generation systems. Maybe that’s because I live in the middle of nowhere though, I’m not sure.
One guy who seems interested in this subject is BoBrown. He mentioned at one point he may be converting his grow to solar soon. You can find him here: Cottage 420's Organic Perpetual Indoor Garden

 

[TorturedSoul]

I suspect you can find much better sources of info on the subject than this forum, but you never know.

Someone - might have been you for all I know, the mind is near the low point in its uneven cycle - discussed solar power from a position of experience in a relatively recent thread... Oh, yeah, the "why aren't there battery-powered grow lights" (or something like that) one. If you can find it, maybe you can have a conversation (either privately or in your thread here) about it. If you can't find that thread, let me know and I'll hunt for it sometime tomorrow.

 

[Weaselcracker]

There was some talk of it here. Might be the one you’re thinking of TS
Using generators to power grow lights

 

[TorturedSoul]

That thread title does ring a faint bell (all bells are faint when you have severe tinnitus). Thank you for remembering.

 

[DrDoob]

I have 26 large solar panels on my roof and according to the app this week they produce about 30 kWh a day here in San Diego, in August it was almost up to 50 kWh. Your 2000w at 18h a day is 36 kWh so you’d probably need a larger system than mine.

My system doesn’t have any batteries which an off grid system requires so I have no idea about that, but they seemed very expensive when I did a little checking. Seems like they don’t hold a ton either so you’d need a lot of them. For instance looks like “the 13.5-kilowatt-hour (kWh) Tesla Powerwall 2.0 has a list price of $5,500” and seems like you’d need at least three of them.

Good luck

 

[PapaSmurfAU]

Have a read of this article. This dude is travelling Australia in a motorhome and is a total off grid genius. His articles are very easy to read and very educational. Motorhome and Caravan Info Australia » Blog Archive » What appliances can I run from my motorhome or caravan solar power system?
I hope this helps.

 

[TurboBucket]

As mentioned solar ain't cheap, and truly off grid is even more expensive with the addition of batteries.

If you want lights you don't have to pay for but your willing to drop that much coin on the gear you could use a generator and a trash/wood gassifier.

 

[TorturedSoul]

If you want lights you don't have to pay for but your willing to drop that much coin on the gear you could use a generator and a trash/wood gassifier.

I saw an old pick-up truck modified to run off of gassified wood once. Seemed like an interesting novelty to me at the time, but the guy said he hadn't paid for fuel in a long time (owned a huge chunk of timber, though).

My only real concern is that such a setup would liberate a great deal of carbon. But so does burning gasoline or diesel, I suppose. IDK.

 

[Weaselcracker]

The wood waste generator is a very inefficient system, or at least very problematic, for anything but a small scale operation. Maybe not even then, if you need it running constantly and don’t have a battery bank for backup. For any operation that needs constant power you need to either continually feed wood to the hungry beast, or else have a backup system for the times you want to shut it down. It usually ends up meaning removing (potentially a lot of) material from the forest and turning it into smoke and ashes. Material that would better serve to feed the natural processes of the forest. It’s a bit of an environmental disaster especially when implemented on a large scale.

 

[TurboBucket]

It was meant rhetorically, no one wants to run a gassifier for a 20 hour light cycle,but glad to see it got your wheels turning.

I come from a land of wood burning boilers and wood stoves so your carbon footprint arguments fall on deaf ears. The local University used waste wood chips in its power plant until a few years ago when the natural gas Genny came online.

The system is designed to keep us dependent on the grid. Why do you think the guy with the water powered combustion engine disappeared? Haha. Anyways.

If you're really serious about getting off grid it's obviously feasible but it WILL cost you a pretty good chunk of change that won't necessarily be recuperated monetarily. What it will provide is a continuous, invisible (to the utility company not the neighborhood) though slightly variable source of energy. For atleast 10 years (excluding batteries) assuming you used decent components throughout.

A grid connected system will cost less and provide similar output.

So before purchasing a system determining your needs for said system are paramount.

 

[Weaselcracker]

I live up by Alaska and have a mill. I burn a lot of wood, as does everyone else around here. At one point the town closest to me considered moving over to wood waste generated power. It became really obvious that it would be a total disaster in terms of the amount of biomass that would have to be shovelled through that thing to keep it running year after year. It always comes down to trying to choose the lesser of whatever evil choices are available. I’m quite impressed with the solar system belonging to the place I’ve been working on lately. Even though they paid a premium to install it, they run year-round using pretty much any amount of power they want, just needing a bit of generator backup in the middle of winter.

Having said that, you could easily pay for running an entire large grow here for the rest your life on-grid and never spend as much money as you would on a solar power system, at least the way the technology stands right now, and with our local prices.

 

[vyserage]

Thanks guys It would seem after doing the research, it would cost me quite too much haha. My power requirements would run upwards of $20k i believe, and that's just not happening lol.

I'll wait another 10 years haha.

 

[Mars Hydro]

Check the real wattage of the light and the voltage range, then choose one solor system which can be suitable.

 

[LEDXpert]

Calculate total power you need. Say its 1000W and you need it 12 hours. You need 12kWh of electricity in a day. Then google your latitude and longtitude to figure out how much sunlight you get for where you are if you point the panels at a given direction and angle. There's charts and almanacs for this. Use winter daylight so in winter your aren't cut short. Winter is usually shorter. Or you can pick a spring day light time if you are in cold area and don't use AC in winter but don't pick a summer day light time as it will be much too short and AC cooling costs aren't 1 to 1 with input watts.

So lets say you get 6 hours of "good" sunlight then you'd need 2kW of solar panel to run for 6 hours. You've now just calculated what you need in a perfect world. Then you suffer from the laws of thermodynamics.

So from solar DC, you pulse it with electronics which is a loss step and then the battery itself heats up as you charge it because of its internal resistance so charging the battery isn't efficient. (lithium ion will be better than lead acid but much more expensive). About 80% of the power will make it in to the battery so divide you panel KW but .8. In this case 2kW/.8 = 2.5kW of panel. You can ignore battery drain because it isn't sitting there for very long until you are charging again. Now you have to take that stored DC power and make AC. Plan for a 10% energy loss step here. So 2.5/.9 = 2.78kW of panel.

So now you've calculated what you need in a perfect sunlight environment with your hardware. Now you have to account for cloud coverage, rainy days etc. Also have to calculate for birds on your panels, dirt collecting, etc. The watt rating of your panel is for optimum conditions. Also heat will reduce efficiency. You also want to make sure if 2.78kW is your exact usage that you have a little extra so you can top the charge off or recover. This de-rating you pick is subjective. Spit balling but maybe 20%. 2.78/.8 = 3.475kW. So maybe 3.5KW or whatever the nearest panel size is.

When you figure this for yourself you'll need to obviously change the watt draw and number of hours per day etc. The 20% I added on you can skimp on but if you're playing it safe I'd put something for that. The inefficiencies for each energy change step you can't get around. Also I'd have plenty of extra battery so you don't wear the battery out by draining it super far every day. So have like twice the kwH in the battery than needed. If you have DIY LED modules you might be able to use a DC to DC supply on those and go straight from the battery and save the inverter step to pick up 10% but don't look at DC air conditioners they are expensive and inefficient.

So with all that power loss you see why people just put it straight to the grid rather than in to a battery and back out. You only have 1 energy loss step from HV DC to AC.