Solar on a budget

[wpmasterdesign]

Just more questions:

How do you obtain water? A well pump requires power. A cistern for hauled water requires a pressure pump system.

Do you use/need a refrigerator or freezer? They need power. An energy star rated full size refrigerator may need about 1.2kW per 24 hour period.

Is the current generator designed for thousands of hours of use? The generator needs to be large enough to charge the final battery bank and durable for years (industrial duty). I have a liquid cooled 4 cylinder genset of 20kW capable of about 80 amps for the 24 volt battery bank. It has 4,500 hours on it.

Definitely develop a spreadsheet listing all your power needs and size accordingly. If you are in a northern climate you are going to be using light bulbs more than 5 hours per night. You can not read in the dark, and sitting in the dark from 7 pm is going to get boring real fast, and the old lady is going to nag you to no end, or leave you..

How many days of autonomy do you want in the battery bank?

There are solar system suppliers with (cabin/house kits) pre-sized with material takeoffs available online. You may get an idea of total costs real fast by their listed kits. I suggest you search the web find some vendors and talk to them. Take a home loan to buy a complete solar power system, and build it once.

As some have said, once you get a battery bank, you get to start a new hobby. You get to refill those fla batteries with distilled water every month! And you need to stock pile (gallons) of distilled in your 400 sqft house to keep it from freezing.

I live off-grid on a remote homestead surrounded by national forest. The off-grid 24-volt solar system is a deterrent for potential buyers. They don't want it.

1. Water is obtained from a combination of a gravity fed rain catchment system and occaccional visits to a fresh water sprinf not far from my homestead.
2. As previously stated, I have a solar fridge/freezer that runs on it's own solar panel.
3. Admittedly no, I do need to upgrade my gen
4.I have already done detailed calculations of my power needs. That is why I know these smaller setups will work. My power use is (and will likely stay) so minuscule that I will never be likely to use over 2.5kwh in a day. And most days will not even reach that.
5. Lighting, again as I already mentioned, is provided by solar lighting systems that are already in place and they have their own solar panels. In the year I have used them, they have NEVER failed to provide the amount of light we need.
6. I would like to have 2-3 days autonomy. I am ok with running the gen if that runs out.

See, one of the reasons I think the modular setup is so great for us is the fact that we do not need to power everything with these systems. A percentage of our power needs are provided by the devices themselves with built in panels. So literally all I need additional electricity for is 2 computers, rare quick printer use, and charging our mobile devices. Thats it. I think alot of folks find it hard to believe that we can thrive on such a low amount of electricity. People have gotten so dependent on it, that is SHTF and the almighty power grid fails/collapses, most folks would be screwed and would have no cluse how to survive without electricity.

This is a big part of why I chose to live offgrid. When (not if) the grid fails we will be fine. I am not dependent on the grid. I am completely free of those constraints. I will still have the power I need. Your grid tied system will have to be completelty reworked when it happens. And since you are relying on the grid primarily, will the supplemental solar you have be enough to power your needs?

I also live off-grid on remote homestead. I have Mark Twain National forest on 3 sides of me. We moved here a year ago and we have been quite comfrotable with the amount of power we have been able to produce. The only thing that is changing, is we are working towards producing more of that power with solar than the gen. As is, I have built 2 of these modular systems so far and for the past 6ish weeks, I have had to use the generator an average of 1-2 times a week. Where as before this, I was using it daily, for 10 hours a day. I have just over $900 invested into this setup, and so far, it working great.

[SunEagle]

It wasn't so long ago, the entire world lived without electricity. I view then as a struggle to stay alive another day, with
hardly any time or energy to spare for anything else. Sort of like avoiding drowning in the water. Certainly not my choice.
Bruce Roe

Unfortunately the world is enjoying the technology that makes their life easier (or some like to think that) but the side affect is they need more electrical power to keep their toys running.

30 years ago 99% of correspondence was done with pen and paper. Now it is done with a few thumb strokes and a # sign. People are addicted to social media and the technology that it comes from. A power outage in a technological society would drive most people up a wall.

[bcroe]

It wasn't so long ago, the entire world lived without electricity. I view then as a struggle to stay alive another day, with
hardly any time or energy to spare for anything else. Sort of like avoiding drowning in the water. Certainly not my choice.
Bruce Roe

[jflorey2]

I live off-grid on a remote homestead surrounded by national forest. The off-grid 24-volt solar system is a deterrent for potential buyers. They don't want it.

I find that many people enjoy the abstract concept of living off the grid, but don't like the work associated with it.

[citabria]

Just more questions:

How do you obtain water? A well pump requires power. A cistern for hauled water requires a pressure pump system.

Do you use/need a refrigerator or freezer? They need power. An energy star rated full size refrigerator may need about 1.2kW per 24 hour period.

Is the current generator designed for thousands of hours of use? The generator needs to be large enough to charge the final battery bank and durable for years (industrial duty). I have a liquid cooled 4 cylinder genset of 20kW capable of about 80 amps for the 24 volt battery bank. It has 4,500 hours on it.

Definitely develop a spreadsheet listing all your power needs and size accordingly. If you are in a northern climate you are going to be using light bulbs more than 5 hours per night. You can not read in the dark, and sitting in the dark from 7 pm is going to get boring real fast, and the old lady is going to nag you to no end, or leave you..

How many days of autonomy do you want in the battery bank?

There are solar system suppliers with (cabin/house kits) pre-sized with material takeoffs available online. You may get an idea of total costs real fast by their listed kits. I suggest you search the web find some vendors and talk to them. Take a home loan to buy a complete solar power system, and build it once.

As some have said, once you get a battery bank, you get to start a new hobby. You get to refill those fla batteries with distilled water every month! And you need to stock pile (gallons) of distilled in your 400 sqft house to keep it from freezing.

I live off-grid on a remote homestead surrounded by national forest. The off-grid 24-volt solar system is a deterrent for potential buyers. They don't want it.

[Sunking]

See SK's post. You have to dig into the manufacturer's specs to get the actual AH ratings. Good batteries give you AH ratings over different loads - i.e. 220 amp hours at a 100 hour discharge, 190 amp hours at a 10 hour discharge.

Jeff is referring to Peukerts Law which states the faster you discharge a battery, the less capacity the battery has. Box Store Batteries will not publish Discharge Curves aka Peukert Factor.

Look at these two Trojan Batteries. One is the well known T-105 and the other is the T-105RE. Look at the Electrical Specs, the second row down and note the 5, 10. 20 and 100 Hour capacity ratings.

What do you see?

Both are exactly the same.
5 hour = 185 AH, 37 amps
10 Hour = 207 AH, 20.7 amps
20 Hour = 225 AH, 11/25 amps
100 Hour = 250 AH, 2.5 amps

So what is different? Well the 105RE is heavier, cost more, has Carbon Technology which allows the battery to perform better in the PSOC range thus longer cycle life, and has a better warranty. The T-105 carries a 2 year warranty and the T-105RE carries a 5 year warranty makin git the best value for your money. A T-105 will cost you $135 and you replace them every 2 years. A T-105RE cost $160 to $170 and you replace them every 5 years they say. That makes the T-105RE is a superior battery and better value. You get what you pay for, and you had better know WTF you are buying.

Also note the T-105RE or any of the RE Premium Line are not Trojans best battery. That title goes to the Industrial Line and come in 2, 4, and 6 volts with an 8 year warranty.

However never ever parallel batteries or mix old with new. If you do you buy new batteries every year.

[jflorey2]

But wont a marine battery last longer than golf cart batteries?

"Marine battery" is a marketing term.
"Golf cart battery" is mostly a marketing term. All it really refers to is a form factor (GC2) which is common to golf carts. Many types are popular (like the venerable Trojan T105) because they are cheap, you can get them anywhere and they last a reasonable amount of time.

Correct me if I am wrong, but although golf cart batteries do have higher AH ratings, aren't they rated under a lower amperage use? Maybe I am way off and I appreciate being educated if I am. I honeslty know nothing about golf cart batteries.

See SK's post. You have to dig into the manufacturer's specs to get the actual AH ratings. Good batteries give you AH ratings over different loads - i.e. 220 amp hours at a 100 hour discharge, 190 amp hours at a 10 hour discharge.

[Sunking]

But wont a marine battery last longer than golf cart batteries?
And wont they give me longer load times than a golf cart battery?
Correct me if I am wrong, but although golf cart batteries do have higher AH ratings, aren't they rated under a lower amperage use? Maybe I am way off and I appreciate being educated if I am. I honeslty know nothing about golf cart batteries.

Simple answer no. Both are hybrids. Neither are true deep cycle batterries. .

Example Trojan makes the best 6-volt 225 AH battery money can buy model T-105. Many use it for solar because it is available most everywhere. It is a two to three year battery if you give it TLC. It is a Hybrid battery.

Trojan also make a T-105RE which is a deep cycle battery. Same exact form factor and ratings. It comes in a BCI GC form factor, 6 volts, 225 AH. It has 7 poinds more lead and last 4 to 6 years. It cost more than the T-105 and has a longer warranty. FWIW RE = Renewable Energy.

Trojan also makes a line of L16 batteries made for Floor Machines and Zambonis. They also make it in an RE versions. Again heavier, more expensive and longer warranty.

So here is your first lesson.

With Pb batteries (lead acid) there are 3 types out there..

SLI (starting-lighting-ignition) are typically Lead Calcium alloy made with very thin sponge like textured plates to maximize surface area which reduces the battery Internal Resistance. The plates DO NOT extend to the bottom of the jar to allow space for corrosion and debris to settle in the bottom preventing shorted out plate. SLI batteries are made to deliver very high short burst of currents to crank and engine, and then recharge very quickly. They should not be used for cycle applications. If forced into cycle service they will be dead after 50 to 100 cycles. Less than a year. With each cycle you shed plate material and thin plates do not have much material to spare. SLI batteries are only specified with CA, CCA, and MCA. They will not have an Amp Hour rating.

Deep Cycle batteries typically use Lead Antimony plates. The plates are very thick, heavy, and fill the jar. They are made to be deep cycled. Maximum life is obtained if you limit discharge to 50% DOD. The thick heavy plates allow for hundreds up to a few thousand cycles. It is the thick heavy plates and Lead Antimony that give them deep cycle ability. A true deep cycle battery will NOT have any CA, CCA, or MCA spec because of their higher internal resistance does not allow high amounts of current to be delivered without severe voltage drop. You will only see a Amp Hour spec and maybe a Reserve Capacity (RC) specified in minutes @ 25 amps.

Hybrid batteries try to be both SLI and Deep Cycle. Their plates can be either Lead Calcium, Lead Antimony, or pure lead. Their plates are not as heavy and thick as Deep Cycle, but thicker and heavier than SLI. Hybrids have all kinds of catchy marketing names like Golf Cart Batteries, RV Batteries, Leisure Batteries, Marine Battery, Trolling Motor Battery and the list goes on. They can deliver fairly high amounts of current required to start an engine, but not as much as SLI batteries. They can be cycled but do not have the cycle life of a true Deep Cycle battery. The dead giveaway you are looking at a Hybrid battery is they will have both CCA, CA, and MCA ratings plus Amp Hour and RC ratings.

Bottom line here is you need to educate yourself and quit listening to Green Mafia. Anything you take off-line is going to cost you BIG BUCK$, many times more than buying power. That $150 battery gives you $30 worth of electricity before it dies. You need to understand and learn that now. Or else you are going to learn the hard way loosing money.

[littleharbor]

But wont a marine battery last longer than golf cart batteries?
And wont they give me longer load times than a golf cart battery?
Correct me if I am wrong, but although golf cart batteries do have higher AH ratings, aren't they rated under a lower amperage use? Maybe I am way off and I appreciate being educated if I am. I honeslty know nothing about golf cart batteries.

Earlier I was referring to "marine/RV deep cycle" 12 volt batteries which aren't true deep cycle batteries. They are a kind of hybrid battery designed for starting as well as light cycling use. Not sure what you mean by "lower amperage use" but they have higher amp rating than a 12 volt , similar sized battery because they are half the voltage, hence twice the amp hour rating. If that same sized battery had 6 cells and 12 volt instead of 3 cells @ 6 volt it would have approx. half the amp hour rating because of it being twice the voltage. They both have equal watt hours, which is amp hours times voltage

The quote of mine in question is simply stating to another, Badley, that when you are referring to 8 golf cart batteries being about 2000 amp hours isn't accurate and only close if you are using them in a 6 volt bank

In by book I consider golf cart batteries to be deep cycle batteries. They are intended for golf cart usage as opposed to renewable energy off grid use but still are designed to cycle down from full to whatever percentage they get discharged, then recharge and do it all over again on a daily basis, if needed. They are relatively inexpensive and a good choice for a first , learner set. If they have the capacity you need for your usage there would be no need to move up to larger RE batteries. You might spend extra and get yourself a set of , say Trojan T-105's and possibly get longer cycle life.

[SunEagle]

But wont a marine battery last longer than golf cart batteries?
And wont they give me longer load times than a golf cart battery?
Correct me if I am wrong, but although golf cart batteries do have higher AH ratings, aren't they rated under a lower amperage use? Maybe I am way off and I appreciate being educated if I am. I honeslty know nothing about golf cart batteries.

Hard to say. A marine battery as well as a golf cart battery were really not designed for daily cycles with longevity in mind. A quality battery will provide data indicating how many cycles you should get at a specific DOD under lab conditions. Real life can throw in an unknown (such as bad connection or high resistance in circuit) and cause the battery to fail early.

To be smart you may want to then multiply the posted cycle count by 80% although some people have actually gotten more cycles then advertised it is very possible they never discharge more than 10%.

In the end when it comes to batteries I would say "you get what you pay for". Cheap no name batteries will probably not last 50% of their nameplate rating.

[wpmasterdesign]

* 220 Ah (typical) golf cart batteries is 1760 amp hours AT 6 VOLTS. 880 Ah @ 12 volt and 440 Ah @ 24 volts.

But wont a marine battery last longer than golf cart batteries?
And wont they give me longer load times than a golf cart battery?
Correct me if I am wrong, but although golf cart batteries do have higher AH ratings, aren't they rated under a lower amperage use? Maybe I am way off and I appreciate being educated if I am. I honeslty know nothing about golf cart batteries.

[wpmasterdesign]

advice - dont 'bank' on a battery bank .. batteries are the wear item in a system and a large bank is expensive and very hard to take care of properly especially with limited panel, taking them to even 50% on a regular basis will be very problematic, reduce their life, and require alot of attention in a multiple batt setup, think more like 75% to be realistic long term .. you need to 'design' your conditions around the farm there so you need little battery at night .. let me try to put it into perspective - with about 2000ah of battery, which is about 8 or so golf cart batteries, the max load your going to want to support overnight is going to be less than 200 watts if you want them to last and be worth a dam if its rainy for several days straight .. and thats assuming you have at least 1500 watt of panel .... so 'strictly my opinion', invest money into enough panel and charger to take care of things during the day and only enough battery to get by overnight with things set up for max efficiency .. in another words go to sleep and have a very efficient fridge at night ...

Not to be rude, but have you even read through this thread? I mean, everything you mention has already been discusses.
1. I stated clearly that I never let my batteries go below 80%
2. I have also stated that nothing is ever plugged in that is not being ACTIVELY used. Thus, nothing over night, aka, no night load at all.
3.2000ah battery? I have mentioned multiple times this is goign to remain a small, modular systems. I have 2 DC marine batteries, (identical in brand, siz, and purchase date) per modular setup. No single setup is likely to ever have more than a 300 watt load at any given time.

I have a solar fridge that has its own panels and battery backup, so no worries there either.

[littleharbor]

[QUOTE=badley with about 2000ah of battery, which is about 8 or so golf cart batteries,...[/QUOTE]


* 220 Ah (typical) golf cart batteries is 1760 amp hours AT 6 VOLTS. 880 Ah @ 12 volt, 440 Ah @ 24 volts and 220 Ah @ 48 volts..

[badley]

advice - dont 'bank' on a battery bank .. batteries are the wear item in a system and a large bank is expensive and very hard to take care of properly especially with limited panel, taking them to even 50% on a regular basis will be very problematic, reduce their life, and require alot of attention in a multiple batt setup, think more like 75% to be realistic long term .. you need to 'design' your conditions around the farm there so you need little battery at night .. let me try to put it into perspective - with about 2000ah of battery, which is about 8 or so golf cart batteries, the max load your going to want to support overnight is going to be less than 200 watts if you want them to last and be worth a dam if its rainy for several days straight .. and thats assuming you have at least 1500 watt of panel .... so 'strictly my opinion', invest money into enough panel and charger to take care of things during the day and only enough battery to get by overnight with things set up for max efficiency .. in another words go to sleep and have a very efficient fridge at night ...

[Sunking]

One of the reasons I left the city to live off-grid. I am willing to pay as much as I am able in order to do so.

OK we agree than. You willing knew and made a choice to pay 5 to 10 times more for power the rest of your life and spend several days of the year without power. You can escape the city, but no reason to move off-grid.

Modular is not going to work as Jeff and other professionals have tried to tell you. I can tell you how to make as economical as possible, but it i snot cheap, it is what it is.

1. To start with you must choose a panel that will be available and supported for years to come. The Solar boom has gone bust. Panel manufactures are going bankrupt everyday. Soon there will be no US manufactures if there is any left. Stay away from companies that only make solar panels. Stick with companies you know and solar is just a fraction of their biz like Panasonic, Kyocera, Bosch, and Sharp. Those companies have been around a long time and will continue to be around a long time. Use only Solar Panels made for Grid Tied applications. For Off-Grid Solar 250 watt, 60 cells is your best building block to grow with. You must keep the Voc, Vmp, Isc, and Imp equal and matched. If you stick with 250 watt 60 cell panels does that.

2. Next in line is go with a high quality 80 to 100 Amp MPPT Charge Controller. It is going to cost $600 to $1000. If you screw up and say buy a $200 15 Amp MPPT Controller today limits you to 400 watts maximum input battery at 24 volts. To grow will require you to throw it in th etrash and spend $400 for the next small upgrade. Don't make that mistake. A good 80 Amp model today can grow up to:

1000 watts @ 12 volts, DO NOT USE .12 volts for anything. Huge mistake, extremely expensive, inefficient, and dangerous. In short just plain stupid.
2000 watts @ 24 volts
4000 watts @ 48 volts

3. Now for the bad news, Batteries and Inverters. What makes off-grid systems so expensive is batteries. You will be replacing them every 3 to 5 years like it or not. Just the battery cost alone is what makes it 5 to 10 times more expensive the rest of your life. You made that choice and now have to live with it. That is your problem and expense. You cannot add new batteries to old batteries. If you do you make your new batteries old. So with each upgrade comes new larger batteries you replace every 3 to 5 years or you go dark. If you take anything away from this, let it be this. NEVER EVER PARALLEL BATTERIES & BATTERIES ARE NOT 12 VOLTS.

4. With each upgrade likely comes a new Inverter Upgrade. When you select a Inverter, unknowingly you have selected a minimum battery and panel wattage. In other words you cannot say I will just buy a 4000 watt 48 Inverter today and grow into it. Does not work that way. To support such a beast of an Inverter requires a minimum 48 volt 800 AH 2200 pound $7000 battery you replace every 3 to 5 years. A 48 volt 800 AH battery requires a minimum 4000 watt solar panel and 80 Amp Charge Controller. Understand this relationship. Inverter Size shall be no larger than panel wattage. No problem is you have 4000 watts or panels and a 1000 watt Inverter.

5. Now there is one thing you can buy and let the system grow into. Every Off-Grid system must have one or you will destroy your batteries and spend days and weeks in the dark without one. Have you guessed what it is yet. Yep a GENERATOR and a good battery charger. Be sure not to use gasoline. Use LPG or diesel.

6. Lastly there is one thing you cannot have or tolerate. Any shade on the panels. They will need clear view of the horizon to the east, south, and west. If not you wil need much larger panel wattage.

You got what you asked for. A new part time job with no days off and a huge expensive PIA.