Creating power for your home, off grid.
Emphasis on nuts-n-bolts, hands-on projects.
I went through the "batteryless/battery-based" decision process some few years ago when I returned the borrowed equipment that I had been using for a number of years. At the time, the utility power where I was living in the city was very reliable. I thought it would be nice to have the higher efficiency that the batteryless inverters produce.
I also recognised that I would eventually be installing any inverter I bought into my bus conversion, and that I would need batteries to make that work properly. In the end, I chose the Outback 24 volt 3KW inverter that was capable of grid tie, even though this meant having to purchase MMPT charge controller for the eventual need on the bus or when the power failed and I lost my "dump load".
In my case, the "grid tie" was a de facto arrangement. I used the "don't ask, don't tell, just press sell" method, running the old disk-type utility watthour meter backwards as fast as I wanted, and consuming conservatively to spin the meter the "wrong direction" (counting up) when solar production was nil. This is called "Guerilla Solar" here in the states. It works fine as long as you never produce more than you consume, and that the utility is the typically oblivious bureaucracy that most are, nobody notices.
After moving out of the city, I set my solar power system up at my new property and once again began enjoying utility bills that were below the minimum billing amount. The old disk-type utility meter was happy to spin either direction. Unfortunately, the new utility was paying more attention than the old, and they decided after a summer of minimum billings (less than 128 kWh per month), that either I was cheating, or the meter was defective. One day I came home to find that my beloved disk-type meter had been replaced with a shiny new plastic all-digital kilowatt hour meter. Oh, this meter was smart, it could tell which direction the electrons were flowing, indicated by arrows on the LCD display, but regardless of the direction the power was flowing, the digital display continued to increment, counting up for each kilowatt hour I put back into the utility grid. I was being charged for giving the utility clean renewable power!
This wasn't going to work. I went off-grid for almost two weeks while I figured out a solution.
What I needed was a way to dump the excess power into the bottom element of the electric water heater, consuming only the excess PV power without attracting any electrons from the utility side of the meter to join the party.
In the end, I cobbled together an old disk-type kilowatt hour meter, a motor-driven 60 ampere autotransformer (trade name: Variac or Statpower), and a small circuit board full of electronics. Two optical sensors read the kWh meter's disk motion and turn the autotransformer either up or down, depending on which direction the disk is moving. if the disk is standing still, nothing changes, the autotransformer sits idle at whatever position it is at. The output of the transformer is fed as a 0 - 130 volt AC current into the bottom element of the water heater. The top element is connected to the mains as normal, through a wind-up timer and high current contactor so that it can be run from utility power when needed.
Obviously, this system has some lag time, it reacts in a fairly slow manner to varying loads on the house AC system, but it is actually quite effective in keeping my power off the grid. When I have good PV production, I power all the single-phase loads in the house, housetruck, garage, bus and yard and still ahve some left to burn. When consumption exceeds PV production, the autotransformer turns itself down and eventually off, and I consume grid power. I'm back to minimum billing in the utility's eyes.
Using PV is a dingbat, dumbbell way to produce hot water, but I have to dump that stuff somewhere, or I get charged for it!
I've always thought that the system could be adapted to use the inverter to feed excess power into the dump load when the grid is down, controlled by battery voltage instead of a kWh meter. The trick is finding a motor-driven Variac.
In one of the other threads here ("Taming Lester" in the EV forum) I describe using a phase control IC to vary the charging current into the batteries. There is no reason that the same chipset couldn't be used to regulate power going into a water heating element. Depends on how adept you are at circuit design and construction. It doesn't amount to more than a handful of components.
Good score on the batteries, they look to be in excellent condition. Remember that gel-type batteries are very susceptible to sulfation if left discharged for even very short periods (days). Try to keep them topped up whenever possible. The low self-discharge rate is amazing, I have quite a number of these type of batteries, and I give them a top-up charge every few months, it takes them only a minute or two to come up to full charge after sitting for all that time.
The gods of cheap Chinese solar panels intervened yesterday. I was pondering where to put my two latest 80W Sharp panels and then noticed that the array output was a bit off for such a sunny day... Time to get busy with the test meter (again).
One of the 15W panels on the patio was stone dead (again). So I was 30W short even though the other panel in the pair was fine.
So that settled it, the whole lot came out and I made up a couple of wooden rails for the Sharps to go on and screwed the tops to the wall (to prevent any wind toppling disasters). I've left the bottom loose so I can change the angle. At the moment it's on its Winter setting and in the Summer I can put a couple of blocks under the feet to raise them up, making the panel angle lower.
It takes up a lot less space and puts out much more power.
I still need to figure out where to put the other two new panels and what to do with the 15W ones that still work. Maybe time for another car boot sale. Luckily, two of the sets are still in warranty so I can get the dead one replaced but these are pretty unreliable panels so it may be best to get shot of them as fast as possible. The aluminium framed 12W panels (from the same maker) are still going though, so it must be something about the ABS plastic frames of the 15W ones (water ingress?) that makes them fail quite often.
I could replace those eight 12W panels with the other 80W pair. That would give me a net increase of 64W from the same space. Then again, I haven't tested the other six 15W panels on the garage roof to see if they're still alive... Time for the big ladder tomorrow.
I'll also need to look into burying that overhead cable as it casts a line shadow on the panels below it.
Earlier this year I found a 3A 24V charger at a car boot sale and they are pretty rare things but like buses, two turned up at once at the last car boot! There was a 7A one for Â£2 and then I discovered a brand new, still in the box Yuasa switch mode 6A one for Â£10.
The switch mode one has now replaced the original 3A one as it has some intelligence (it counts the bulk time and adjusts the absorption time proportionally), has higher efficiency than the transformer based one and doesn't have any AC ripple on the output. The transformer ones haven't got any capacitors in them so put out full wave rectified ripple chopped by SCRs to limit the absorption voltage... not ideal for gel batteries (even though both claimed to be for sealed batteries). If I can find some cheap big caps, I might upgrade them but flooded batteries aren't so fussy (and as all the old flooded batts I have kicking around are pretty rotten already, it doesn't matter).
I now use the old 3A one to dump what little excess charge there is on sunny days into the old flooded bank that is still in the living room . As it will be charged as a secondary bank via the solar mains, it can be some distance away from the main system. Just as soon as I get some racking for the store room, I'll put the spare bank out there. It can then be used to support the main bank at night by using the old spare 1kW 24V inverter to run the new 6A Yuasa charger to support the gel bank. I can slave the small inverter from the SoC alarm output on the SmartGauge. Obviously, it wastes a fair bit of power using inverters and mains chargers like this but it does allow me to store more power that would otherwise be lost altogether. In the summer, when there's more spare power available, I can substitute the 3A charger for the 7A one (or even run both in parallel for 10A).
I got the pricing on the new Morningstar TriStar MPPT controllers. They cost more than the Outback FM60's but have better communications. One thing I'm trying to confirm from Morningstar support is if they have current limiting. The tech guy from Deka recommended that I not try to charge the gel batteries faster than their 5hr discharge rate, to stop them from heating up. That's only 29A charge rate. The Outbacks have a programmable current limiter so that although the controllers are rated to 60A, they recognised that only large batteries (or AGMs) can actually accept that much current so you can program any current limit between 5A and 60A to suit smaller batteries but using an oversized array for better performance in variable weather.
I've also been beta testing the new version of the Morningstar MSView logging and control software for their software guys. I'd had trouble with the published version on their web site on my old Windows 98 laptop that I'm using to program the chargers and monitor how well they are charging the new gel batteries.
I may possibly just get another SunSaver 15 MPPT. It has some potential advantage anyway to have three 15A charge controllers as then different segments of the array that are in shade at different times of the day can be tracked individually for maximum power. It would also get around the current limiting problem as I could stagger the charge set points so that as the battery voltage rises, the chargers would gradually drop out (once the battery voltage has risen above each set point). That way, absorption current could be limited to the 28A that my two chargers can put out but if a large load was turned on, that would cause the battery voltage to sink towards the lower set point and so the third charger would automatically cut back in to take up the load.
I got some news back from Morningstar. Both the Sunsaver and Tristar MPPT controllers can have a user set current limit but they forgot to include the parameter in the programming wizard in the MSView software. He said their testing team isn't so sharp at spotting broken or missing things... Funny that I managed to spot these things in a couple of days playing with the software on three different OS PCs (Win98, XP and Vista) - and I've also got a day job that isn't software testing.
Actually, it was and the day wasn't much better. So, it was indoor tinkering today. The Yuasa charger is not quite ideal for gel batteries as the Yuasa SLA batteries are a type of AGM battery. So they set the voltage a little high at 29.0V for absorption. If I wanted to leave the thing unattended while charging the Deka batteries, I'd have to fix this.
The helpful folk at Yuasa had riveted the case shut but I could see three preset controls on the circuit board and the one closest to the vents was labelled "FV Adj", which I presumed to mean the float voltage. So it was worth a closer look inside...
After drilling out the rivets, I found that the other two presets were for the absorption voltage and a current limiter.
The fan cools the heat sinks with the input and output transistors but this isn't what gets hot. There are some damping resistors on the mains side of the SMPSU that get very hot (measured 130'C) and on the output there's a couple of current sensing resistors (145'C). The fan doesn't have its intake against the vents so it only sort-of cools the inside. More like just stirring the hot air rather than any forced ventilation .
Apart from the dodgy cooling arrangements, it looks like an intelligent charger, using a PIC micro-controller as it's brain.
So I connected the charger up to the old flooded battery bank (as it wouldn't mind if I got the voltage a bit wrong) and let it charge up. When it got to 28.2V, I started tweaking the absorption preset control down and kept an eye on the meter. Not having any remote temperature compensation and thinnish output wires meant that as the current reduced, the absorption voltage at the battery terminals kept creeping up. So I adjusted the thing so that it stayed at 28.2V near the end of charge before it went to float.
Actually, at the present room temperature of about 19'C, I should be charging at 28.56V but at least this way I can't overcharge the gel batteries with this thing. The solar chargers are temperature compensated so they will top off the last few percent safely. This thing is only for bulking up the bank to somewhere near full in mid-winter so it's better to err on the low side.
We've had a load of snow here (more than in the last 30 years)... At first I managed to keep the panels all clear of snow as they are only on the ground / garden wall / garage roof. But in the end the snow was falling thick every day and so much piled up on the garage roof that I couldn't get to them so I had to just content myself with the ground and wall ones. Not that it made much difference, the sky being nearly black each day.
The charge controller data log told the story. 20Ah in 5 days. On a clear sunny winter day I can make 50Ah in an afternoon.
This picture is from December (before the big snow of earlier this month). I've got one more 40W panel to go with the spare one I picked up in the summer and so they could finally enter service. Hastily made wooden runners and bolted nearly vertical to the wall. They pick up the winter sun that comes in at only 15 degrees above the horizon at this time of year. I also wheeled out the spare 48W array that I'd mothballed when I put together the second 160W array that I'd bought with the gel batteries a while ago.
What happens to it if I install it on the ruff and have for period of time no power drawn out of it because it will take some time to get all connected and ready.
Will it get hotter?will it damage the cells?What happens to the generated power if is not used and the panels jut lay there on the full sun day after day?
Could I presee any problems or damage?
You might consider covering all or part of the array with black plastic when you are working on it to prevent any voltage from being developed. This would lessen the possiblity of electric shock or short circuits when it is being handled. The rest of the time, it actually would be better to just leave it uncovered, no harm will come of an open circuit PV system.
The voltage generated by a PV system that isn't connected can be compared to a storage battery that isn't connected to anything. There is voltage present, but no current will flow without conductors connected to a load. Just be respectful of the voltage when you work on it and all will be well.
What is the other crucial components to good solar system.
I'm planing to use batteries from golf carts(deep cycle) and large tractor batteries converted to alkaline.
Then there should be something that controls the charge between panels and batteries .
Then there should be something to convert the battery power tp 220v (usa) standard.
Planing to power water heater for start.
And if possible my well pump.(all 220v).
Imagine some control that will allow the water to pump any time on demand but not use the heater heating when water is pumping to minimize size of the draw in one time.
It will be combined with solar thermo heating system.
So what components is that i'm looking at. here.
Some diodes,do hikies ?
A charge controller is necessary to insure that the batteries are kept fully charged without overcharging them once they are full, rather like the regulator on an automotive charging system.
Converting DC battery power to AC appliance power is accomplished by an inverter.
Neither charge controllers nor inverters are devices that are easily made at home. Even I purchased manufactured units.
Making hot water with PV power is not a very efficient use of high quality electric power. The only reason to dump PV electric power into water heating is because you have more power then you can consume with appliances. A direct water heating panel is ~much~ more efficient at making hot water, and much less expensive as well. If you are going to use a water heater to dump your excess PV power, no inverter need be necessary, the electric elements in a water heater can run on DC, but the thermal cutouts that stop the water from boiling have to be rated for DC or they will fuse and burn up.
If you are going to integrate water pumping, battery charging, water heating, etc, some dedicated electronics for controlling the flow of current into the various loads would be required. It can all get very complicated rather quickly.
My advice would always be to start small, get practical experience in building and installing, identify your needs, then plan for bigger and more sophisticatd systems as your confidence grows. Solar is not a trivial expense. I wish I had invested in hydro power equipment instead of solar. Now that I have a source of water, I could be be making a lot more power for a lot less investment if I used hydro instead of solar.
If you did not touch on converting lead acid battery to alkaline then you are up for surprise.
There is whole community (much like here) that is oriented on this subject.
You can take old week sometimes dead battery that utilizes lead/acid and with inexpensive chemicals convert it to alkaline with longer life time and better cycling capabilities.IF YOU USE LEAD /ACID BATTERY IN YOUR LIFE THIS IS MUST TO DO PROJECT!
Water heating is the biggest chuck of energy in the house.
Using thermo solar to preheat the water and then the rest to top it of with electric heating is my plane.Why?
Water is more likely to use in day light.
It will simplify the project as only one unit is powered with solar system.
As you mention may by be even power converter is not needed to heat the water with PV, so auxiliary heating circuit/system can be installed separate from the original one to have redundancy.
If something goes wrong the worst case you just do not have hot water.
It will create larges savings in long run.
The water pump runs only when water is in use,in day light more likely.Also possibility to install 12v water pump so inverter will not bee
If installed properly and functioning right thys system provides one puzzle to self sufficient home.That is if power grid power is not available you will have water and you will also have hot water.The rest is fire place to cook on /heat , and you set to roll power or not power.
Not mentioning that the water system can also utilized heat exchanger in the fire place and adding wind mill power will add more energy to your established system .All totally do it your self project.
Further it can be expanded that hot water is used to heat your in floor piping system to provide heat.
All this i found as the plane for me.
I hope that fro start the 800w would be enough to start topping of the water heater.The thermo project have to be finished first,the Finnish on the battery conversion that so far is going well,then solar pv system,fire place...........
It would take a snap to have it done with some money.
But it will take little by little to do on the no budget i have available.
I learned with more time more improvements and simplifying ideas will come.So no budget is not a bad think after all.
I have no means of water source like energy that is on my property.
But if you describe your idea and possibly how to make something like the hydro generator I'm in to install it on neighbors/state creek near by.
some people have done some experiments here.
Bottom line is:
Drain the battery (careful ! you can get hurt,recycle acid)
Fill with h2O shake and drain few times over to clean it out.
Use baking soda to neutralize any spills and flushes.
fill back with solution of this:
http://www.chemistrystore.com/Chemicals ... lfate.html
4oz to 10 oz to gal of h2o (more alum in lower temperatures to lower freezing point)
Fill the battery up with it.
charge and discharge few times(up to several actually) to bring it to full life.
It IS A LIFE!
Use at your own risk. Yah, right like I head to put this line here for some reason.
It is alum but there is so much types of alum that you better stick with this one i posted as the youhoogroups rocky recommended and tested for years.(like 30+ years)He head some 15 years old batteries tat re still hot.
Although I guess it shouldn't make any difference if I gave them the acid in a dead battery or just decanted into something else. After all, it would be more environmentally friendly to re-use the battery than recycle it.
There's one really old battery that is still sort of ok that might be the first candidate and if that works, I might try the bank of half-killed batteries I took out of my solar system.
The stuff I read at Sepp Hasslberger's blog was fascinating.
Does beg the question though that if it works so well and is cheaper than using sulphuric acid, why don't they just make them like that in the first place? Some did say it didn't work well with new batteries. A guy tried it with a dry bike battery that had never had acid put in it and it didn't work well at all, so maybe it only works for eeking out some extra life from nearly dead batteries.
The answer might be the same reason that a couple of years after Edison sold his NiFe battery tech to Exide in 1972, they canned it and nearly nobody makes them now. NiFe batteries can last 20 years and are pretty much indestructible (can over charge, under charge, deep cycle for thousands of cycles and be rejuvenated just by replacing the electrolyte). Who'd want to sell a battery that would last you a lifetime? Much more cash to be made out of selling lead-acid batteries that need to be replaced every 4-5 years
Also skip the Epsom salt and do the chemical I recommended earlier.
The used battery have sediment of sulphate that function as catalizer when new alkaline electrolyte is introduced.
That is why new batteries are unsuccessful.
Also they are more prong to freeze so store accordingly.
I pure the acid in 5 gal buckets.Recycle or save cose after while it completely clears out and is crystal clear acid again to be reused in batteries or anodising.
I'm definitely gonna have to upgrade my charge controller now that I'll have over 1.1kW wired up to that 400W controller - lucky it's not sunny yet!
I knew it was a good idea to go overboard with buying that 3kW inverter... gives you a target to aim for .
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