• Post Reply Bookmark Topic Watch Topic
  • New Topic
permaculture forums growies critters building homesteading energy monies kitchen purity ungarbage community wilderness fiber arts art permaculture artisans regional education experiences global resources the cider press projects digital market permies.com private forums all forums
this forum made possible by our volunteer staff, including ...
master stewards:
  • Nicole Alderman
  • r ranson
  • paul wheaton
  • Anne Miller
  • Mike Jay
  • Jocelyn Campbell
stewards:
  • Devaka Cooray
  • Burra Maluca
  • Joseph Lofthouse
garden masters:
  • Dave Burton
  • Greg Martin
gardeners:
  • Mike Barkley
  • Shawn Klassen-Koop
  • Pearl Sutton

Off Grid Solar  RSS feed

 
Posts: 6
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
As a man of squishy sciences (biology, mycology, medicine- all squishy things) I’m less informed with things electrical. I’m setting up an 11kW solar system with PV to power my off grid home. Any helpful design sites out there? I’m having a hard time figuring out the best way to “plug it all together” including cables connecting the panels. YouTube has failed me. Much appreciated!
 
Posts: 29
Location: Huntsville, AL
17
  • Likes 3
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator

Jeremy Allen wrote:As a man of squishy sciences (biology, mycology, medicine- all squishy things) I’m less informed with things electrical. I’m setting up an 11kW solar system with PV to power my off grid home. Any helpful design sites out there? I’m having a hard time figuring out the best way to “plug it all together” including cables connecting the panels. YouTube has failed me. Much appreciated!



Jeremy,

There is an lot to learn to successfully design and install a off-grid good Solar PV system. If you end up doing it wrong, the results can be anywhere from wasting a lot of money to burning your house down (yes, I have seen this).

So if you don't have a reasonable amount of expertise in electrical work in genera,l and Solar PV in specific, I would first advise that you work with somebody who does. And my experience is that the folks who are experienced in off-grid Solar PV designs (which requires sizing out batteries and figuring out discharge curves) are a small subset of the professional solar installers I run into. Most solar installers I have met specialize in installing grid-tied systems since this is what they can sell the most of.

(As for YouTube, it has a mix of good, bad, and ugly advice, so I wouldn't recommend using that as a primary source of information).

When you work out the economics, the payback period for grid-tied systems looks a lot better than off-grid or grid-interactive, and they require much less maintenance or thought from the user. So the sales team for most Solar PV companies have an easier time selling the typical homeowner a grid-tied system.

That being said, I actually prefer off-grid systems (possibly with grid fall-back if a grid connection is easy where you are located). They just take careful design and some thought and care to operate.

I actually teach a 20-hour Ecological Solar Design course that is designed to teach regenerative designers how to work with Solar PV professionals to add solar to their designs in as sustainable and regenerative a way as possible. (Please notice that this course doesn't try to teach you to actually be a certified installer yourself. That is normally a week-long hands-on course for just the basic certification that only covers grid-tied. Off-grid is at least another week of school.)

My first piece of advise is to start by figuring out how to reduce your electrical loads by 90%. Then the rest gets much easier, and usually much cheaper.

If you are thinking about an 11 kW solar array, I would want to know what you are planning on powering with the array and how many kWh of total consumption per day you use on average.

If you do chose to tackle this project on your own, please understand that there are a large number of tasks you are going to have to handle to end up with a good result. These include things like:
*Decide on the optimal mounting location and orientation for your array
*Do a solar insulation survey to determine how much solar radiation is falling on the site during the day for each season of the year
*Do a complete load analysis that accurately reflects you peak loads, average loads, and worst-case energy consumption through the different seasons
*Decide on array voltage, whether to use power optimizers, the best serial/parallel arrangement to meet your goals, the proper gauge of power wire to handle the current load and minimize voltage drops
*Analyze your load requirements to determine the total size of battery array needed, pick your battery chemistry, and figure out your discharge curves so that you don't destroy your batteries in short order
*Pick the best equipment to meet your goals, including sizing your charge controller and inverters
*Install everything to full electrical code (if you don't and something bad happens, your insurance company will probably use this as an excuse not to pay)
*Configure the equipment to run in the required modes and then monitor and maintain the system to insure proper operation

All of these tasks are much easier for a smaller array than for a larger array. This is another element that recommends towards starting by figuring out how to reduce your loads.

If you decide to go forward, I would certainly recommend doing a lot of your own ground work and research and then finding a good Solar PV designer and installer who has done a bunch of off-grid work to help you out. If you find somebody good to work with, you may be able to keep costs down by doing certain things yourself. You just will want help at certain critical phases unless you have the proper expertise yourself.

 
Posts: 323
Location: Pittsburgh PA
12
chicken duck forest garden fungi trees woodworking
  • Likes 1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
11kW is pretty big. I would like to believe that I could have installed my 12kW system myself...but.

With the federal tax discount/return (which you can only receive if installed by a professional) I could not buy the materials cheaper. Not even counting the labor. We also have a 7 year maintenance plan and it saved us money on home owners insurance. The company who installed my system also tweaked the system to be more efficient and cheaper than i had planned. Using equipment and programs which I couldn't afford.

All being said...I would equate installing a system of that size, to require a skilled level of roofing knowledge, to at least be familiar with installing a whole home 220 volt system (assuming you're running conventional appliances due to the size) knowledge of local codes, and if you require Suplimenterary heat ditch your gas and invest in heat pumps, and heatpump water heaters.

Any questions lmk. 12.7kw system in sw Pennsylvania.
 
Jeremy Allen
Posts: 6
  • Likes 1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Alan, Chad, thanks for the replies.  I was trying to keep it generic so it'd be more helpful to others looking for starter guides on this.  But maybe it's more helpful to be more specific about my situation?

Firstly, Alan, can you talk more about your Ecological Solar Design course?  What are the skills taught to a non-electrician like myself?

Anyway, my situation is that I am moving into an off-grid yurt in the coming months.  It would cost >$80k to have power brought in, and then I'd get the pleasure of a monthly power bill and the company assuming ownership of all of the equipment I'd need to install to get the power to my yurt (and future house) site.  So off-grid just made a ton more sense.

I already have most of the equipment.  I got a killer deal on the Clean Energy Storage Powergrid PG11, here's the stat sheet.  It contains the AIMS 8kW Power Inverter Charger, the Outback FlexMAX 80, and the Nuvation NUV300 battery controller.  It's supposed to be "plug and play" but I don't have the skills to know the minutia required.  I also got a crazy good deal on Canadian 275w solar panels, so have 20 of those.  I don't have anything to connect the panels to the inverter/charge controller.  I see the schematic in the Powergrid instructions, but wanted to make sure I was doing everything properly (as you pointed out, small mistakes can be big problems).

I have a southern exposed area that's close to the yurt for the panels.  I ultimately want some type of pole mount, since I could more easily shed the snow and change the angle to catch the sun in winter better.

Hmm, what else?

I will reach out to the local contractor who does off-grid systems, but felt like I had most of the work done and just needed to "plug it all together."  Of course, I'm not so naive to think that's really all I need to do...  :)

Thanks for your, and anyone else's, advice.  Trying to save money, but like not exploding.

Jeremy
 
gardener
Posts: 535
Location: SoCal USA
88
bike cat composting toilet dog solar trees wofati
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator

chad Christopher wrote:With the federal tax discount/return (which you can only receive if installed by a professional)



Is there a specific form the installer fills out, or is an invoice part of the form to give the IRS? Reading their rules for the credit and instructions for the tax form, I don't see anything where it says a pro must install it, or what documentation if any to submit with the return (you obviously need receipts to keep for your records, or the audit would be very painful!).
 
pollinator
Posts: 2385
Location: Massachusetts, Zone:6/7, AHS:4, Rainfall:48in even Soil:SandyLoam pH6 Flat
122
forest garden solar
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
These guys will sell you a pre-assembled/pre-wired and tested power center that is truly plug and play.
https://www.wholesalesolar.com/1891316/wholesale-solar/complete-systems/the-ranch-11.34-kw-36-panel-mission-solar-off-grid-solar-system
$12,000 for a 11kW Solar System (solar panel + railing + support + misc)
$10,000 for a 9kW/Power Center (pre-wired & tested charge controller+inverter+combiner box)
$10,000 for a 61kW Battery System
$1,000 for Shipping (this includes everything=solar panel+railing+power center+battery+misc)
Total = $33,000

For $5,000 more they have a 12kW solar panel + 12kW power center + 61kW battery bank upgrade.
https://www.wholesalesolar.com/1890750/wholesale-solar/complete-systems/the-ranch-12.6-kw-45-panel-astronergy-off-grid-solar-system

Let me know what your thoughts are with this kind of setup. How does it compare to the price that you paid? Can you post or link to the diagram that came with the system that you bought.



 
Alan Booker
Posts: 29
Location: Huntsville, AL
17
  • Likes 4
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator

Jeremy Allen wrote:Alan, Chad, thanks for the replies.  I was trying to keep it generic so it'd be more helpful to others looking for starter guides on this.  But maybe it's more helpful to be more specific about my situation?

Firstly, Alan, can you talk more about your Ecological Solar Design course?  What are the skills taught to a non-electrician like myself?

Anyway, my situation is that I am moving into an off-grid yurt in the coming months.  It would cost >$80k to have power brought in, and then I'd get the pleasure of a monthly power bill and the company assuming ownership of all of the equipment I'd need to install to get the power to my yurt (and future house) site.  So off-grid just made a ton more sense.

I already have most of the equipment.  I got a killer deal on the Clean Energy Storage Powergrid PG11, here's the stat sheet.  It contains the AIMS 8kW Power Inverter Charger, the Outback FlexMAX 80, and the Nuvation NUV300 battery controller.  It's supposed to be "plug and play" but I don't have the skills to know the minutia required.  I also got a crazy good deal on Canadian 275w solar panels, so have 20 of those.  I don't have anything to connect the panels to the inverter/charge controller.  I see the schematic in the Powergrid instructions, but wanted to make sure I was doing everything properly (as you pointed out, small mistakes can be big problems).

I have a southern exposed area that's close to the yurt for the panels.  I ultimately want some type of pole mount, since I could more easily shed the snow and change the angle to catch the sun in winter better.

Hmm, what else?

I will reach out to the local contractor who does off-grid systems, but felt like I had most of the work done and just needed to "plug it all together."  Of course, I'm not so naive to think that's really all I need to do...  :)

Thanks for your, and anyone else's, advice.  Trying to save money, but like not exploding.

Jeremy



It sounds like you have a number of good components, but putting it all together properly takes a little work. I have worked with the Outback FLEXmax before, as well as Lithium Iron Phosphate batteries (although not the PG11), but I am not familiar with the Nuvation NUV300.

Since you have the charge controller and the inverter from different vendors, there may be a bit of trickiness is making sure they play together nicely. When you buy both from the same vendor, they usually have some way of talking to each other to do a few "smart" things that help out and let you manage them in a unified fashion.

On the Ecological Solar Design class I do go over a lot of these concepts in a fair amount of detail, but don't get into all the specifics that an installer would need to know. I concentrate more on covering the concepts a permaculture designer looking to integrate solar into a larger regenerative design would find useful.

I also take a much bigger-picture approach to what "solar" is. In my mind, your garden is the most sophisticated use of solar power. Sticking up solar panels to create electricity is dirty and inelegant in comparison. And how about a solar clothes dryer (aka a clothes line) instead of an electric dryer? Or passive solar gain from a properly designed building?

You would probably get a lot out of this class, but I am not going to have time to teach it again in the near future. Fortunately, the EAT Network had me do an early version of the class as a series of 14 webinars which they recorded. The first one is free at the EAT Community website and you can register for paid access to see the rest if you think it would be helpful. (They have recently changed around their paid access plans, so you will have to look at the details if you are interested.)

Good luck with the project and please report back on your progress and what you learn!
 
pollinator
Posts: 541
Location: Michigan
41
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
5500wp and 11kwh is serious yurt power. You will likely have room for solar electric heat domestic hot water, rock tumbling irrigation, etc., on many days. Looks like good stuff.
 
chad Christopher
Posts: 323
Location: Pittsburgh PA
12
chicken duck forest garden fungi trees woodworking
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator

Mark Tudor wrote:
Is there a specific form the installer fills out, or is an invoice part of the form to give the IRS? Reading their rules for the credit and instructions for the tax form, I don't see anything where it says a pro must install it, or what documentation if any to submit with the return (you obviously need receipts to keep for your records, or the audit would be very painful!).



You can just hang onto your recipts, i think the pro install has to do more with grid-tied and SRECs. So you are correct.

Its Its highly unlikely residental systems would be looked into by the IRS anyways.
 
Mark Brunnr
gardener
Posts: 535
Location: SoCal USA
88
bike cat composting toilet dog solar trees wofati
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
My coworker directed me to altestore.com which has some pretty good prices on parts relative to other sites I've seen so far. I picked up a temperature set thermometer at Amazon for $25 so I can convert the used chest freezer I have to a refrigerator instead, I haven't attached it to the kill-a-watt to test yet but the average energy use I've seen for that size is in the range of 100-300 watt hours per day. I'd also have a couple 8-12w led bulbs, a laptop that runs between 50-100 watts based on whether I'm playing a demanding game or running something like Blender vs web surfing, and probably a clothes washer that runs once a week or so. Assuming a surge when the fridge compressor kicks in while I'm also washing clothes and gaming will need something like a 500w inverter that can handle a surge in the 700-1000w range. They have a 24v 600w Samlex for $250 which can surge up to 1000w which seems like a good fit.

My estimated use (once I confirm the fridge power use) is around 750 watt hours per day. The site's calculator gives me 8.97kwh battery capacity for going 5 days of cloudy/rainy weather, assuming 2 sun hours per day in winter for the area. But that's allowing 50% depth of discharge, while I'd prefer keeping them over 80% for the extended life if possible. But essentially a 9kwh set as 3 strings of 250ah each at 12v, for 750ah total, or if I went 24v 3 strings of 125ah for 375ah total.

For panels, the calculator claims just 487.5 watts is necessary for charging the system, so 2 panels at 300w each will be "overkill". I was thinking at least 4 panels wired as 2 strings of 2 so they would also be at 24v, but would get the Outback Flexmax 60 which can handle different voltages in and out, and 4 panels might be more insurance on cloudy days for partial charging.

So the costs would be:
4x300w panels @ $208 each: $832
Outback Flexmax 60: $399
Samlex PST 600 inverter: $249
4x215ah, 12v FLA batteries @ $296 each: $1184

Total: $2664 plus tax, shipping, and wiring costs. I expect to purchase batteries in person to avoid the transport costs, and wouldn't know about wiring costs until I have the distances figured out but several hundred bucks as a guess there. So $3000+, plus a few hundred for a charger and a few hundred for a generator perhaps, compared to the estimated $24000 to have grid power brought to the property, seems like a good deal. Plus I'd get to deduct 30% of that from taxes as well so even better.

What about things like a dump load for when the batteries are fully charged, and lightning arrestors or other bits and pieces, say a breaker box and breakers that then run in the house for the outlets? Can you use a normal box for that, or is a special type needed for solar?
 
Mark Brunnr
gardener
Posts: 535
Location: SoCal USA
88
bike cat composting toilet dog solar trees wofati
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
I found this calculator very helpful for determining the size for an off grid system, where I won't be selling surplus to the grid so my goal is maximizing gain in the short winter months with a much steeper angle than you'd use for year-round generation back to the grid:

https://pvwatts.nrel.gov/pvwatts.php

Ends up 67 degrees tilt and 180 azimuth provides the best gain in December and January for my site, and while I could adjust the tilt for more gain in the summer it would be wasted unless I were to use power tools or something during the summer to benefit from all the extra power. There's no planned AC unit for the Oehler/wofati design!
 
Posts: 2
Location: Trafford, PA, United States
1
chicken food preservation homestead
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator

chad Christopher wrote:11kW is pretty big. I would like to believe that I could have installed my 12kW system myself...but.

With the federal tax discount/return (which you can only receive if installed by a professional) I could not buy the materials cheaper. Not even counting the labor. We also have a 7 year maintenance plan and it saved us money on home owners insurance. The company who installed my system also tweaked the system to be more efficient and cheaper than i had planned. Using equipment and programs which I couldn't afford.

All being said...I would equate installing a system of that size, to require a skilled level of roofing knowledge, to at least be familiar with installing a whole home 220 volt system (assuming you're running conventional appliances due to the size) knowledge of local codes, and if you require Suplimenterary heat ditch your gas and invest in heat pumps, and heatpump water heaters.

Any questions lmk. 12.7kw system in sw Pennsylvania.



Hi Chad,
I am also in SW PA and dying to know who put your solar array in?
Thanks!
Cari
 
Posts: 5
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
study electrical theory or get someone you trust that has and I don't mean trust money wise, I mean trust mathematically. Don't be afraid to start small either. Collecting energy is one thing, whether solar, wind, water, manual horsepower etc, but sustaining it, storing it and transferring it to what is needed and when it is needed can vary greatly in difficulty depending on your needs. If I just need my green house a few degrees warmer for an early start and a late finish on a green house I don't even need to store or convert power but if I need to power a single wide trailer with house hold ammenities I need to store and convert at probably a higher cost than the form of collection i.e. solar panel.
 
Posts: 107
Location: Nomadic
2
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
FYI. Last I read Electrodacus has plans to run his home in Canada entirely on 13kw PV with his own design non mppt controller and low voltage PV. As a owner of a high voltage mppt system I am intrigued. And I’d consider it if I was to do it over and if low voltage wire runs were not very long. But you haven’t installed anything yet so you could sell your equipment and start designing from scratch. Many people are not satisfied with their first system and build another. But some plan so carefully they are satisfied. And if one is shopping for bargains then one gets by with what one finds.
I’ll second the suggestion to study theory and principles.
 
frank li
pollinator
Posts: 541
Location: Michigan
41
  • Likes 1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator

Jeremy Allen wrote:As a man of squishy sciences (biology, mycology, medicine- all squishy things) I’m less informed with things electrical. I’m setting up an 11kW solar system with PV to power my off grid home. Any helpful design sites out there? I’m having a hard time figuring out the best way to “plug it all together” including cables connecting the panels. YouTube has failed me. Much appreciated!



I would download or refence and read the manuals for all of the equipment you have and the stuff you might buy.

From there you should have a better understanding of the system and its requirements. The manuals usually have a glossary of terms and  explain function and relation of equipment within the system, generally.

The do's and dont's are quite important.

Get on altestore.com and backwoods solar electric and read/watch the tutorials and explanations there.

There are actually not many major components to relate to and understand. There are not many different types of connection to be made.  Integration into building electric or yurt electric and other facets will add some areas to know.

Have enough battery.
Have enough charger.
Have enough inverter.
Have proper size wiring/cabling and overcurrent protection.
Have a minimal backup system and or spare components, especially in remote settings.
Make observations noting the system, usage and weather and operate accordingly.

 
Mark Brunnr
gardener
Posts: 535
Location: SoCal USA
88
bike cat composting toilet dog solar trees wofati
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
I'm using altestore.com for purchasing my own gear, and they do have a turnkey system that will produce 10kwh or more for most of the US, depends on the number of sun hours in winter (and they have a map showing that) from this 7.4kw system: https://www.altestore.com/store/solar-power-systems/off-grid-home-solar-power-systems/base-kit-3-off-grid-74kw-residential-solar-power-system-p40620/ for just over $12k, plus the cost for batteries. Purchasing batteries locally to avoid the shipping costs could save you a lot of money if that's an option. This setup is already wired up and on a plate for you can mount it on the wall, then plug in the panels on one side and your batteries on the other. You are paying extra for them to do that but you'll know it's correct and working when it arrives.
 
frank li
pollinator
Posts: 541
Location: Michigan
41
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator

Mark Brunnr wrote:I'm using altestore.com for purchasing my own gear, and they do have a turnkey system that will produce 10kwh or more for most of the US, depends on the number of sun hours in winter (and they have a map showing that) from this 7.4kw system: https://www.altestore.com/store/solar-power-systems/off-grid-home-solar-power-systems/base-kit-3-off-grid-74kw-residential-solar-power-system-p40620/ for just over $12k, plus the cost for batteries. Purchasing batteries locally to avoid the shipping costs could save you a lot of money if that's an option. This setup is already wired up and on a plate for you can mount it on the wall, then plug in the panels on one side and your batteries on the other. You are paying extra for them to do that but you'll know it's correct and working when it arrives.



Turn-key is a pretty heavy term here, as with most kits.

Hardly alte's or your fault, nobody could account for mounting and wiring options.

They have an option list. The system could easily cost an additional $8k-$10k with a moderate battery, mounting, electrical enclosures, wiring, battery enclosure, screws, conduit, sealants, zip ties, fuses, breakers, disconnects, comm cable, routers, etc.

Even if you mounted it on wood and went spartan on stuff, wire and screws and incidentals would run a couple thousand unless you are thrifty and have access to stuff. A battery could be from $2500 and up, likely.

It wants at least 200ah per inverter.
 
Mark Brunnr
gardener
Posts: 535
Location: SoCal USA
88
bike cat composting toilet dog solar trees wofati
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Yeah I've been looking at buying parts separately, as their smallest systems seem like overkill for my estimated needs. But there are lots of bits and pieces to include it seems. I stopped by a local store that sells the deep cycle batteries, what I save in shipping I lose to California pricing... I'm planning to get a pair of lower AH 6v Trojan batteries that I can use for learning, and hopefully when I'm ready to build I'll pick up 4 of the big Rolls FLA batteries (assuming there aren't any new battery breakthroughs by then). The 683AH 6v models are $1k each online, $1200 each locally, hopefully buying them locally when not in California will be the best of both worlds, lower price and no shipping costs. It'll take 4 of the beasts for enough kwh to limit the DoD to 20-25%, and Rolls says that will get you into the 7000 cycles lifespan range. $4k for 18-20 years of useful life out of a 16kwh battery system seems pretty good.

Still trying to work out storage for the batteries and gear, seems keeping the batteries in that magic 70-80 degree F range for the best capacity and lifespan is key, and with FLA off gassing having it outside any living space and properly vented is important. A separate garage/shop positioned for best solar gain, that I mount the panels to and store the batteries and gear inside, seems simplest. I could also have the well and water storage in there, get it insulated and maybe have a RMH for winter heating. A small, insulated room would be easier than an insulated enclosure, when the batteries get into the 300-400 pound each range... while I can lift that now, the 60-70yo me likely won't! So dolly access is also key.
 
pollinator
Posts: 206
Location: North central Ontario
19
books chicken dog earthworks homestead kids cooking solar wood heat woodworking
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Hi Mark,
When you do go down the road to a better Battery try to balance out total storage capacity with amount of solar array so that you can spend a good amount of time in a day in absorb. What can happen with an oversized battery is it can spend a great deal of its life in float or on heavy discharge days it will spend several days in bulk trying to catch up. For smaller arrays the amount of amps it can put into the battery at absorb is not ideal for that sized battery. I would choose a smaller battery bank and spend the difference on a larger array. The Surrette/Rolls 1450 size batteries are a nice compromise and one man can lift the damn things!
Cheers,  David
 
Mark Brunnr
gardener
Posts: 535
Location: SoCal USA
88
bike cat composting toilet dog solar trees wofati
  • Likes 1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
I've seen mention of aiming for 10-20% of battery capacity when sizing panels, so i was thinking 6 panels at 300 watts each and something like a 15-16kwh battery bank. My calculated use is around 1500 watt hours a day so the idea was sizing it for staying at 20% depth of discharge on a given day or better, and most likely I'd be topped off most of the time. But since this sizing is based off of worst case of several heavy cloud days in winter maybe a smaller bank and a charger/generator for cloudy weeks is a better option.

The Rolls S-1450 would definitely make it easier to move around, but I'd need 6 of them in series to hit 12v and they get a bit over 2000 cycles at 20% DoD. The Rolls 6 CS 17P is a 6v battery so just 4 needed to hit 12v and similar total AH doing 2 parallel strings of 2 in series. A bit heavier per battery but in the easy enough for me range, and at 20% DoD they are rated for just over 7000 cycles. Prices seem to come in 2-3 times greater, so perhaps a little better or a wash overall, and the shorter life of the smaller batteries allows revisiting other options more often.

Then there's options like the Tesla Powerwall, 13.5kwh capacity and 100% DoD, and I've read they last around 5 years beyond their 10 year warranty... how can anyone know that, when they've been on the market for just 4 years?!? They run $7800 including the gateway which is a big investment, could just look at the old iron Edison batteries for that price. That Tesla system could be located in the house and doesn't require monthly watering. But the Rolls battery options claiming 7000 cycles is a bit over 19 years at half the price of Tesla-checking the distilled water monthly isn't that big of a deal assuming I can keep them the proper temp and ventilated.

It's amazing to me to consistently read how the average US family is using 30Kwh of electricity per DAY, so "a Powerwall can only provide a few hours of battery power..." My current electrical use is just under 3Kwh per day, and that's with a window AC unit, large TV and fridge in a poorly insulated house. But no kids makes a big difference too. I expect I could go a week in my future home on over 13Kwh of storage, especially with partial charging on cloudy days. But that's without needing any AC, using a RMH and rocket oven/hot water, and converted chest freezer.
 
Well don't expect me to do the dishes! This ad has been cleaned for your convenience:
Soil Testing: Genius or Snapshot of the ever-changing?
https://permies.com/t/113090/Soil-Testing-Genius-Snapshot-changing
  • Post Reply Bookmark Topic Watch Topic
  • New Topic
Boost this thread!