I have been gone for a bit again. Mainly just surviving and enjoy life up here. While today is a bit chilly (17F), most days have been warm and sunny. 30s and up. Even the lows lately have been pleasant. (Teens and up)
My solar system is really holding up. It produces more than I need. The weather to date has mostly been sunny/spotty cloud days. Today marks the third time I have seen it Cloudy a few days in a row.
A few weeks ago, I spent all evening watching movies on Netflix with the 42in HDTv. So, was using some power. On the computer there is an app that shows all the data for the solar system. I use it to monitor how much I am using in relation to its charging (During the day). Well, the previous day I sort of used a lot of juice and didn't entirely have enough sunlight outside to charge it fully...
OK. Let me start again. I only use about 20% of what is available from the system. Say, 2KWh a day. 2000 watts. That is the same size as my entire array but when you factor in multiple hours of daylight you begin to see that I am 'wasting' sunlight by not using it. A few weeks back, my neighbor, Judy, gave me an Electric heater. One of those oil filled types. During the day, I let the sun warm the house through the south exposed glass. It does a beautiful job. However, it does take a bit of time to get it all going after a chilly night. So, there is a few options to speed it along. I can either just wear a light sweater and let it gradually come up through the 50s and into the 60s throughout the day naturally or I can burn wood. Burning a single box full of willow will heat the place enough to get it into the 60s (starting in the high 40s (Small house has little mass to hold the heat regardless of insulation) when I wake up) and allows the sun to hold it there for the day.
Another great idea is when it is sunny outside, battery full, turn on the electric heater (1500Watts) and the fan behind it to blow it around. Works out great. First time I did that, I went out for a few hours with the neighbor to do laundry and grocery shop in town. Came back and it was 80F inside. Yuck. I also managed to 'use' 8kwh worth of juice instead of the normal 2. Plus, had a full battery to enjoy for the evening (5kwh worth). Over the next few days I continued to use the heater. The average usage (in kwh) proceeded to shoot up. I was a happy clam. I was using all of that 'wasted' available electricity. Plus, there was no longer a need to burn wood to heat the house in the mornings. Saving it for the evening. Greatly extending my stockpile of willow in the creek on the northern portion of the property.
Side note: I have been using the willow since Sep 22, 2013 when I moved in. Aside from the occasional bits of 'real' wood I've had over the last few months. Still, there is more to be harvested in the creek. I find it amazing. :)
The electric heater... Many people tell you, you cannot use resistive heating appliances on Off-grid systems. It uses too much juice! What are you, Stupid?? HAH!
Problem is, those people either use a lot of power to begin with and do no have much available for extra or simply have smaller systems than mine.
My first idea still is to create a gazebo with glass walls and dump the excess electricity into a hot tub, but, until that gets going I might as well use it to heat the place up. :)
So, a few weeks ago, I left the heater on all day. It was a Tuesday, so I went out on my usual boys lunch date out with my friend up the street. This time, Instead of returning after a few hours, I spent some time at his place. Came back a little after 3pm, which is around the time the sun falls behind the mountain range and the solar output drops to next to nothing.
Hmm. I messed up. See, that day happened to be a "Spotty Cloud" sort of day. Clouds would cover the sun, then it would blow off, intense sun would hit the panels then shoot 40 amps into the battery, but another cloud would come say hello, get in the way, impede those 40 amps actually getting into the battery... and so on. Well. I used 5-6kwh that day and the battery was only charged up to 3/4ths or less. Probably less.
It is difficult to determine State of Charge based on voltage. I still need to purchase an Amp-hour counter.
That night I settled in. Proceeded to fire up netflix. Carry on watching movie after movie on the big screen.
Oops. Looking at the computer app. My voltage dropped to 46!! I have a 48 volt system. It is actually 54v when fully charged. The cells (16 of them.) have to each be above 2.5 volts and less than 3.65v. Otherwise you over charged them or over-discharged them.
I am not using lead acid batteries. Practically everyone uses them. I do not. They are heavy. You cannot routinely use more than 50% of their capacity if you want any sort of life out of them. Plus they produce hydrogen gas. Meh.
I use LiFePo4 (Lithium) batteries. The stuff they use in creating electric cars. My entire 5Kwh bank is 150lbs. Each cell is about 10. They do not gas. They can be discharged 80% daily and still have over 3000 cycles. You can just let them sit and they will not self discharge over time.
I love them, but they are expensive.
What you have to do is balance them. So the minor difference in capacity of each cell doesn't have you over discharge or charge one cell amongst the others.
I did that around 7 months ago when I first set it all up. However, I must have not done it perfectly.
That 46v I saw. Meant that when I took a volt meter to each battery, most were 2.8v but one was 1.7!!! EEKs
I completely shut the system down. It was midnight. Then went to bed. Hoping that my poor battery would come back. Remember we arent supposed to bring it lower than 2.5!
Woke up. Feeling better. The cell recovered to 2.2. Good sign.
I proceeded to spend the next two days (willingly) without power other than my solar powered lamp. With a volt meter I lined up the cells with the highest voltage to the lowest. 16 in a row. Then took number 16 and connected it to number 1. Positive with positive. Negative with negative. Then 15 with 2. 14 with 3. 13 with 2. So on and so forth. Thus averaging out the voltages. The high ones would slowly bring up the lower ones. After 30 minutes. I would take them all apart. Re-order them based on voltage. Then do it again. Again. Again. Again. At night. I would let them rest. Not connected to anything. Slowly the voltages averaged out. Nothing more than a few milivolts apart.
When I woke up the next day. I would do it again. (The voltages change over time as they rest and bounce back). After two days of messing with them (I could have just charged the one low cell and been back up the next morning but decided to really go at it) I had them all within 4 millivolts. It was spectacular! (0.004) (Hence one cell would be 3.333 and another 3.337)
Then I hooked them all back up and let the precious sun, bake the heck out of them. :)
It has been weeks since that incident. I keep checking them with the voltmeter. In the morning before they charge (hence at rest), while they are really getting charged up, and at night when they are resting after charge.
The voltages range between 2mv and 10mv difference. Cell #6 is still happy as ever.
I'm elated. The batteries are so tightly in tune that I will never have to re-balance them again for the life of the bank. :)
(The funny thing with batteries. When you get them new, they are not fully developed. It takes a few cycles before their capacity is fully established. So, those balanced differences change a bit, but over time, they grow tighter together, fluctuating much less. )
I haven't been using the Electric heater much lately. Although I could. I'm just happy as I am. The house has been warm. Sun doing its thing.
Today is a chilly one. 15F outside. Normally its the 30s-40s. I have a fire going. 75F inside. A window is cracked open for fresh air as the firebox consumes its little inferno.
I've been using pine logs lately. It has been a couple weeks since I've had to go into the creek.
Oh, how easy it is to burn logs. Rarely having to get up to add more to keep the fire going. The house gets unbearably hot. I have to fully open a window and shut the damper on the firebox in order to keep it 78-80F inside. Sometimes, depending on the outside night temperature, I may even open the door a little while! But. Life is cozy.
I am a happy man.
What about water? :) Oh, that. I have been lucky that my neighbor lets me tag along with her to get some. She has a well to her house but for drinking water she prefers to go fill up at this free artesian well down the way. It is just this spigot that comes out of the ground with naturally flowing, beautiful water. Many people around the area use it for the free water. I fill up several 6 gallon buckets and good for a few weeks.
My long term solution for water. Rain. I am starting to love mathematics. Since building and determining everything, I have 're-learned' all the geometry and algebraic formulas from years ago. There was the time I wanted to figure out the exact volume of my building, even with the triangular ceiling portion in order to figure out how many btu/hr was needed to keep it 70F inside when -20F outside. (It made me much more comfortable knowing it was possible and quite easy to do with wood) Now with water.
The mathematics goes as such. For each Inch of rainfall, on a hundred square foot 'roof' (10x10) you can collect 60 gallons. Or 60% (.6) So, from that, you can determine how many inches of precipitation your area gets a year on average. Determine what you need in gallons a year to live your lifestyle, and poof, you find out how large a roof you need plus a cistern to hold it. (water generally comes in seasons so you need to hold it in large quantities to average out the year)
For me, just showering, food, drinking, etc my tiny house of 200SF roof area can get me by as soon as I hook up gutters to it, plus purchase a 1500 gallon cistern. So far I use about 1500 gallons a year.
BUT. Here is the fun part about math. Take it to the extremes!
I have 2.88 acres. That is 125,450 SF (about 44k per acre) If I put a liner over everything, pea gravel on top and sloped it all to a giant lake cistern.... with 13 inches of rain (although another website says we are closer to 16)
= 75,271 gallons per inch
= 978,531 gallons collected (13in annual)
Guess I am a water millionaire! What are you going to do with your millions??
Be safe everyone!
Ps. I've been pondering building some earthen/cob with lime plaster structures on the property. Plenty of ideas are running through my head as winter carries on. ;)
|Meh. Not a happy indoor Temp. Crack a Window!|
|My new pretty stack of wood for $70. 3/4Cord|
|Did some moving around. The Power Center.|