diy solar

diy solar

newbie planning offgrid cabin

tlstumpf

New Member
Joined
Feb 22, 2021
Messages
7
Hi everyone,
Me and my brother are building a new cabin which is mile back in the woods on a logging road with no ability to get power run to it. location is Leeper PA. Which I show gets about 2 3/4 hours of average sun in the winter. Our current cabin is on the last legs of its life and maintenance was getting to be more costly than building an new camp. Plus becoming more a pain for senior citizens (grin). About 8 yrs ago I put a 100 watt relogy panel, inverter, battery to run lights. This has been great but we still run generator anytime we need water. fill buckets to flush toilet which the woman folk are not happy about. 2 key things we want is running water and a fridge. Also may want to consider a minisplit system in the future so ability to expand is likely needed.

I would like to be able to figure out what I need to order in one to two months for the new cabin. We just finish framing and closing in the cabin. Metal roof and siding to keep maintence to minimum. The panels will mount on a 30x12 roof in the back facing south. If that not big enough we would add panels on the west.

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We plan to heat with wood burning furnace. Water heater will be propane. Below is what I have for load estimate. Main loads are all new so I can not measure.

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I live 10 hours away from the cabin so reliability is a must.

I'm kind of a jack of all trades, I've been a general contractor and a software developer and recently retired.

Been reading and really get hung up on AC coupled versus DC coupled. Also we close the cabin down and winterize it Jan/Feb/March.

Any thoughts and question to get me thinking on the right track would be very welcomed.

Terry
 
What is your budget?

18 panels (2 rows of 9) 250-400 watts each (whatever is the best value/inexpensive in your area) would give you 3500-7000 watts an hour on a good day. I would consider trying to have a couple arrays pointing SE, S, SW if possible to extend your usable sunlight hours.

Run that into a big ass charge controller/inverter and then feed as much battery storage as you can fit/afford. I am thinking minimum 400ah at 24v would get you through one day of no sun. Maybe think about having a generator to charge the batteries if the sun decides to hide for a while. The well pump might be an issue depending on how much power it pulls on start up surge.

Might be a good idea to build a small power shed to put all this stuff in, maybe combined with your well, so you can insulate though whole deal?
 
iamrich, Thanks for your response.

Budget like most projects is over. So trying to save where we can and not overspend needlessly on things we don't really need now. but want flexibility to add later without doing complete tear out. That seems to be one of the advantages of an AC coupled system. Add panels or more storage easily as long as inverter is large enough.

Equipment will be inside on second floor of camp. Plenty of room there and short runs to panels.
 
My system is small and simple, so that is my experience. You might get a lot better advice from those that are doing the same thing. I would probably go with something like:

MPP 6548 or some similar all in one unit $1500
2 rows of 8 panels (should fit perfect and leave a little roof on either side ~12x27 feet. I would go used 250w panels (~$60 shipped from Santansolar or local) 4kw worth $1000
Batteries is the big question mark. DIY from China, something plug and play locally? This could be $2-4k, but I would suggest at least 200ah at 48v to get you through at least 1 complete 24 hour period with no sun.
Racking, wiring, combiner, fuses, misc $500

If you can somehow time all your needs to when you are getting max PV, you could probably run less battery and stretch it farther. Like if you could only pump water to a storage tank when you have solar, and maybe put the fridge on a timer to run max during solar, and maybe cut off after.
 
You seem to not use it much in the winter. Your first half of the loads table could probably be zeroed over the winter. Note that sun is low, and few hours when it's cold. The best you can do it put 1 100W panel with a battery and load (low voltage protect the battery), and see what you are getting for power. It may be 10-20% of the maximum solar available in the summer, but it may power some of the lower power usage devices.

Can you collect rain? If that back shed roof is 30' x 12', you have a good sized roof. Look at the average rain in your area and determine how much falls on your roof. An underground water collection sistern (ie a 2000 gallon septic tank) could run most of your water with a 3-5 GPM RV pump at 12V. Very little water is used for drinking. You can filter or disinfect that small amount.

I have a camp above Utica NY and the December 21st solar tilt is about 23 degrees from vertical. You may be about 30 degrees for PA. Your rear shed roof may collect snow and have no power collected for the winter. There are calculators and US surveys on what the solar power is that hits your panels. I've done some, but really rely on a plastic roofing square on the panel. At exactly solar noon (mid way between sunrise and sunset) set a roofers square on the panel and tilt it to be perpendicular to the sun. You can move an object from the top of the square to the bottom and the shadow shouldn't move.
 
Nice cabin ,
I would go with a 48 volt system , a good quality inverter charger I use out back equipment
But snider or magnum would be just as good I think .
I would start with a 3600/4000 watt inverter out back fm80 / morning star / snider charge controler .
4000watts of solar .
try 8 golf cart battery’s 215 amp hour at first And see how you do ?

I use 16 GC battery’s in series parallel configuration

I think extra batetery capacity will allow you to keep the battery’s a little longer / discharge less ,
Run the generator less and not have to worry about power and if you have a accident and kill your batteries
They don’t cost a Fortune to replace.
I run my place on 120v with no 240 at all .
I don’t need A/C at all , the house dosent get above 67o at all , all summer long I have r60 ceilings r40 in the walls ,
2 and 3” Dow blue board under the slab .
It takes 4/5 days to warm the house up in January with the wood stove cooking .
But once it gets warm I burn 2 of 3 firess a day a few splits at a time And stay around 68o
I don’t burn a over night fire at all the house temp stays up around 64o and a fire in the morning warms the place in 20 minutes .
It looks like you could build a utility area under the house on the front right side , I would rather see your solar equipment in a cool location .
My system is very small and dosent take up much room ,you can read about it below .
I paid 2700$ 4 years ago but it really makes diy power easy .
once I powered up my system I use it to finish up the house .
It ran my compressor , table saws ,chop saw , and hand tools even with no sun in the winter.
I screwed the power panel to the wall and hooked a string of 8 battery’s
To my inverter then propped up a string of 3 295 watt is solar panels on a south wall and we where
Back in the 21 Century with power .
I would gather equipment at home and work on the solar install a little bit every week end .
I mounted my panels to the roof on iron ridge 1000 mounts .
I have 15 more panels that will be ground mounted with a second out back fm80 CC soon .
My well is @ 735’ and my pump will be set at 700’+- I have a grundfos 6-3 sqf solar pump .
I’m just getting ready to slip it into the center of the earth to get some water .
I’m in a cold snowey place and burn wood 10 months a year .
I just got 3” of snow this morning .
I’m 3 hours north west of NY city on a Mountain @2400 feet .
the snow is the one thing the solar guys don’t talk about ☹️ My panel where covered for 10 weeks this year .
The truth is if I look at my power panel I use 200/300 watts a hour with the frig freezer rv pump and every thing else I use day in and day out .
My Radiant floor heat is not hooked up yet and I dont do Landry there yet .
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Thanks for the replies, been away a few weeks working on the camp. Headed back up soon. Currently I'm leaning on a Sol Ark 12k all in one. Pricy but will give me lots of room to expand if needed. I also decide to use 3 48V GYLL with a cabinet that can add 3 more if needed. 14 310 Watt panels.

I will have to deal with Snow. Is there a good way to clear the panels without damaging them?
 
I have a extendable pole in the pic above with a plastic squeegee , it works good if you clean them before the snow freezes on the panels .
I do have a plastic Windshield scraper that I can put on the pole to scrap ice ,
But this year I had 3’ of snow on the panels .
 
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