diy solar

diy solar

Off Grid with 2hrs winter sun. Doable?

squarpeg

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I realize this is a very broad question. I am building a small house. Have always wanted to try off grid solar. Unfortunately land is heavily forested, slopes north. I got one of those solar pathfinders and tried various spots. November, December and January look pretty grim in terms of direct sunlight. I am working on clearing what I can, but thinking I will max out at 2hrs of direct light during those 3 months. The house will be pretty spartan on electric devices, essentially led lights, laptop, small tv, small fridge, well pump. Initially thinking I could afford 5k worth of panels. Can anyone offer thoughts on getting through the winter with that setup? I do have a generator, prefer not to run. solar3.jpg
 
If you want to do solar under those conditions consider.
1. make certain no shade can get on your panels.
2. consider a 2 axis tracking, or a single axis tracking adjustable tilt polar type mount.

A fixed array will get about 72-74% of one that can track the sun.
 
Go to an Insolation calculator, find out how may hours equivalent full sun you would get, with panels tilted to catch that sun. Multiply by PV panel PTC or other real-world ratings (or assume 75% of STC ratings). See how many panels it takes to produce the Wh you need.

5kW of panels? Like $2500, maybe $1250 used? (mounting hardware may cost more than panels.)

Cold weather? Either select a battery that can be charged in extreme cold, or keep it warm.

Tracking? :ROFLMAO:
Not for 2 hours sun!
 
A 10kWh power budget for winter is not too bad if you have another source of power for heat, hot water, and cooking. Unfortunately you will have to live with about 5-6kWh average when you factor in weather, or run your generator to make up the difference.

Small fridge should be ~0.7kWh/day, TV and other bits and bobs might add 1kWh, lights about 3Wh/SF is a good budget.

The well pump could be a challenge though. A storage tank could reduce the problem-- run the well pump once a week on generator and use a small booster pump from the tank. I assume you would need some form of heat though for the storage tank.
 
Fridge and well pump are the biggest hurdles. The size of the fridge isn’t an issue, they all operate about the same average Wh daily… ya need kWh… and to get that in 2h~ Is an issue… pump operation load can be mitigated with dc pumps, and above ground water storage and transfer pump…
Find out how many kWh ya need a day, and see how much solar you will need in only 2hr… I’d guess you need around 10kWh a day, so you’d need 5kW of solar to do it… however it is more complicated even than this…
What angle is the sun to the horizon for those 2 hours? Directly overhead? Low on the horizon? It makes a difference in solar gain… you might be hard pressed to exceed 400W/m2 so panels may only produce 40% their rated output…
Then weather losses… light clouds and the irradiance drops, down another 50%. You will need additional power source during those times… heck, with only a 2hr window, minor cloud passing can cut production massively.
 
The typical 230V submerged deep well pump would be impossible. I would research and find a very efficient DC well pump, and having a shallow well would be a huge plus. You would also want the option to power your pump with a gas generator.
 
The typical 230V submerged deep well pump would be impossible. I would research and find a very efficient DC well pump, and having a shallow well would be a huge plus. You would also want the option to power your pump with a gas generator.
You can run a 1/2hp without much of an inverter if it is a PSC (permanent split capacitor) two wire type pump. I have one of these PowerJack LF inverters that is rated at 3000w (230v). I ran two different PSC 1/2hp pumps on it without issue. They also run on my pair of Growatt 3000s. The Powerjack wouldn't run a 1/2hp that used a start capacitor and relay (3 wire pump). So it does matter what type of pump, which largely determines that starting amps.

edit:pair of Growatts
 
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Branches of course provide some shade, but not as much as those leaves in your photo. No leaves unless you have evergreens in winter.
 
You can run a 1/2hp without much of an inverter if it is a PSC (permanent split capacitor) two wire type pump. I have one of these PowerJack LF inverters that is rated at 3000w (230v). I ran two different PSC 1/2hp pumps on it without issue. They also run on my part of Growatt 3000s. The Powerjack wouldn't run a 1/2hp that used a start capacitor and relay (3 wire pump). So it does matter what type of pump, which largely determines that starting amps.
With the 3 wire pumps, you can try and replace the control box starting capacitor with a slightly higher value capacitor. You can drive the inverter with lead acid high amp batteries and super capacitors. With my pump you need a low frequency 230V inverter that can surge to 5K watts. Power Jack makes "8000" AMG inverters that can do that. My pump needs 20.5A @ 230V inrush, in a short burst.
 
The Trees are all hemlock and pine so I am stuck with shade year round. A lot of that is on my property line so I am limited to what can be removed.., but there is some I can cut. I am in Vermont, lots of cloudy days, also generally snow on the ground during those months. I heard that reflective light can help but not sure how much that really makes a difference. I have not figured out the well issue yet. I do not have a well at the moment. Have been considering going with a shallow well, which there looks like a good spot for it. Otherwise it will be a drilled well. I do have a basement so could set up a tank in that for pumping periodically with the generator. Heat, hot water, cooking is all wood or propane. Have considered getting a propane refrig but they actually seem to use a lot of propane. For the cost I could probably run the generator.
 
Will you put the panels on the roof or ground? Pushing them up in elevation and designing the roof for good orientation might help you gain an hour in the winter. Not sure where your best return on investment is though.
 
Will you put the panels on the roof or ground? Pushing them up in elevation and designing the roof for good orientation might help you gain an hour in the winter. Not sure where your best return on investment is though.
The panels will be on the ground mounted. The house is closer to the tree line, I looked at it, it won't work during those 3 months despite panels being higher up.
 
I realize this is a very broad question. I am building a small house. Have always wanted to try off grid solar. Unfortunately land is heavily forested, slopes north.

PLEASE STOP RIGHT THERE !!!
YOU ARE BEING LED DOWN THE GARDEN PATH !!!!!!!!!!!!!!!!!!

I live in a 1700 acre protected forest,
near Algonquin Park Ontario Canada - deep North rural & remote. similar but more harsh.

First: review THIS THREAD.

Currently out of date But you'll get it!.
- 240VAC Pump = horse pucks !
My well is 280' deep in banded granite, 6" bore & casing. I use a Grundfos SQ5 DEEP WELL PUMP @ 200' DOWN it's a soft start 120V unit. Pushes to a 50 gallon pressure tank, then another 75' to house through a dual filtration system with only 3psi loss. Starts @ 550W draw & terminates @ 1100w @ 55PSI WHEN DONE. You NEVER notice pressure drop.

I VERY RARELY DO THIS NOW, BUT WATCHING THIS THREAD !!!

Use SERIOUS critical thinking on advice given. I'm one of the originals on this board and don't theorize or bs.... No garden path distractions!

Hope it helps.
Steve_s.

Btw:
I use 3.7kwh for 24hours virtually year round.
Have 24V/1190ah battery Bank with Samlex EVO-4024 Low Frequency Inverter/charger 98% efficient.
10 days reserve power & triple redundancy for heat,water & power generation as. I can be snowed in for up to 7 days before plows show up. Plus plus plus.
 
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can you take down some of the trees to open up to more production? that's going to cost a heck of a lot less than trying to make 2 PV hours work. plus you'll have a bunch of fire wood.
 
PLEASE STOP RIGHT THERE !!!
YOU ARE BEING LED DOWN THE GARDEN PATH !!!!!!!!!!!!!!!!!!

I live in a 1700 acre protected forest,
near Algonquin Park Ontario Canada - deep North rural & remote. similar but more harsh.

First: review THIS THREAD.

Currently out of date But you'll get it!.
- 240VAC Pump = horse pucks !
My well is 280' deep in banded granite, 6" bore & casing. I use a Grundfos SQ5 DEEP WELL PUMP @ 200' DOWN it's a soft start 120V unit. Pushes to a 50 gallon pressure tank, then another 75' to house through a dual filtration system with only 3psi loss. Starts @ 550W draw & terminates @ 1100w @ 55PSI WHEN DONE. You NEVER notice pressure drop.

I VERY RARELY DO THIS NOW, BUT WATCHING THIS THREAD !!!

Use SERIOUS critical thinking on advice given. I'm one of the originals on this board and don't theorize or bs.... No garden path distractions!

Hope it helps.
Steve_s.

Btw:
I use 3.7kwh for 24hours virtually year round.
Have 24V/1190ah battery Bank with Samlex EVO-4024 Low Frequency Inverter/charger 98% efficient.
10 days reserve power & triple redundancy for heat,water & power generation as. I can be snowed in for up to 7 days before plows show up. Plus plus plus.
You need to work on reading comprehension. I wrote "the typical 230V submerged deep well pump" would be almost impossible. You are using a 120V pump that costs $2500.
 
One of the insolation calculators that @Hedges was referring to may have been PVWatts. It will give you a good sense for the difference in estimated production you will get for a hypothetical system at your latitude in winter and in summer. It cannot account for trees or weather phenomena for your site but it may have a reasonable prediction using a weather station nearby. That is the production or generation side of things. Others have given you ideas how to look at the consumption side of things.
 
You need to work on reading comprehension. I wrote "the typical 230V submerged deep well pump" would be almost impossible. You are using a 120V pump that costs $2500.
I know what I paid for pump and it wasn't no $2700. BUT it was before Covidus Stupid which made everything ludicrous. I paid $1300 Canadian.

A split phase 240 pump with Soft-start isn't that severe either with an appropriately sized pressure tank.
 
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