John B's posts

$4.60 per watt is not a bad price for less than 200 watts, but as your system expands you want to be sure that the panels you add on will have the same specs as the original panels otherwise you will need to add a new charge controller for each new type of panel that you add on to your system.

A 15 watt ungrounded panel is not much of a hazard when it is the only source of power, but when it is included into a system where power may be fed back to that panel in a fault situation then you have a problem because you are violating electrical codes that are in place for your own safety.

Actually a 120/240 step-up transformer will work just fine. I have one (Outback X-240) running my 1HP well pump and 1HP pool pump.

If he opens the connection to the pump it is very likely that it has an option inside to be wired either for 240V or 120V. Note that 230V and 240V is within the same tolerance and can be used interchangeably.

My 1HP pumps use about 1200 watts when running (10 amps at 120V or 5 amps at 240V) with about one-and-a-half times that at start-up, so I would estimate that his 3/4HP pump would probably draw around 8 amps continuous at 120V or 80amps at 12V from the batteries.

As for the rest of the advice, I'm inclined to advise Patrick to go back to the drawing board. Perhaps he can get Canadian Tire to exchange those ten 15watt panels for a single 150watt panel or two 75watt panels. Those 15 watt panels were designed for trickle charging batteries and he will only give himself a headache trying to build a system 15 watts at a time.

Jerry,

This site is worth a read. It should answer many of your questions.
http://www.batteryuniversity.com/

John

I agree with you that price is no guarantee of quality. Even Mercedes Benz have made their fair share of lemons. However, when you're spending a large sum of money it doesn't hurt to have a warranty. That's why I still buy my tools from Sears. When I break a tool they replace it, no questions asked.

Walt,

Your spreadsheet is comparing the initial costs of the batteries whilst you really need to compare costs over the useful life of the battery.

The Rolls Surrette for example has a useful life of around 15 years and I believe the manufacturer will warranty the battery for 10 years. If the cheapest battery in your spreadsheet is only warrantied for 1 year, then it has to cost less than one-tenth of the price ($/Kwh) of the Surrette to be a better deal.

$/Kwh/Years of expected life is a much better way of measuring your true costs.

http://store.altenergystore.com/Enclosures-Electrical-and-Safety/Overcurrent-Devices/Circuit-Breakers/Outback-2-Amp-Din-Rail-Mount-Breaker/p5811/


According to the specs they accept AWG #6 through to AWG #14. If you can pull the AWG #18 wire out after the screw has been tightened, then just twist another small piece of AWG #18 wire around the exposed tail of your connecter to "fatten" it up before terminating it into the breaker.

Eric,

I believe that the "Whisper Controller" is a charge controller of sorts. The Whisper Controller and the pv charge controller should be able to connect to the same battery bank if they are the same voltage. Charge controllers for wind turbines usually have a "diversion load" to dump any excess current once the batteries are fully charged since spinning blades in high winds do not turn "off" as easily as pv panels. Heating elements in water heaters make good diversion loads.

James,

I hope we haven't put you off by giving you the worst case scenario, but you should know it and you can decide for yourself what amount of risk you can live with.

Typical battery efficiency is usually given between 70 and 80 percent, but I was quite surprised to read a report on the Sandia Labs site somewhere that under certain conditions it can be as low as 50 percent. It's a very good site for research.
http://www.sandia.gov/ess/

Now on to a practical answer to your question. The first thing that a charge controller does is take whatever energy it has available and put the battery through a charging cycle. Once the battery is fully charged, the charge controller will actually turn "off" the pv panel so that no current is flowing. Now if you put a 40watt load on the battery then you interrupt the charge controller in its single-minded pursuit of charging the battery, and knocks it off its bulk/absorb/float cycle.

So if you have a pv panel capable of delivering 7 amps (84 watts for easy math) at 12v, and say your fully-charged battery requires 1 amp to maintain the float, then your 40 watt load would be drawing its 3.3 amps directly from the charge controller. The charge controller would also be delivering 1 amp to maintain the float voltage, so it will effectively be "de-rating" your 84w panel down to about 50w.

Now if you add a second 40w load, the charge controller would turn the panel power back up to 72w and service both loads while still maintaining the 1 amp battery float current. Add a third 40w load and suddenly you are drawing more current than the pv panel can deliver so you start taking current out of the battery and the battery voltage drops. The charge controller "sees" the drop in battery voltage and says "hey, I'm not in float mode any longer. It's time to re-evaluate the situation".

For practical purposes you can think of the charge controller as dumping everything that it gets from the pv panel into the battery, and the load as drawing all of its current from the battery, but in reality it is slightly more complicated than that.

For a 12V system your math is easy. Just divide your watt-hours by 12 to get that will be taken in amp-hours from the battery. In your case, 240/12 is 20AH.

One small caveat is that the efficiency of a lead-acid battery can be anywhere from 50 to 80 percent. So in order to recharge a lead-acid battery that you have taken 20AH from, you may have to put back the equivalent of anywhere from 25AH to 40AH from your charging source.

As for the PV panels, I would recommend (without having used them myself!) a couple of CIGS modules such as this one that will work well in low light conditions, and is attractively priced at $5 per watt.
http://store.altenergystore.com/Solar-Panels/51-to-99-Watt-Solar-Panels/Global-Solar-60W-12V-Framed-Solar-Panel/p5574/

Voltage drop calculations are really only applicable in situations where you have fixed voltage, such as 120V in a panel box or the output from your charge controller.

Lets say for example that the output from your turbine is 50V. Any loss at all from that, or even 50V itself, would not be able to charge a 48V system.

Now lets say that you can crank up the output voltage of the turbine up to 80V. Here you have a situation where even a 10% drop in voltage is not going to prevent the turbine from charging the batteries. What you will have is power losses in the wire because of the resistance of the wire. The less ohms per foot, and hence the larger AWG number and more expensive the wire, the less losses you will incur.

In pv systems, the voltage drop has much greater relevance for the distance between the charge controller and the battery, and is not that important between the source and the charge controller. Remember in PV systems mppt charge controllers actually vary the incoming voltage along the I/V curve to maximise the power gain.

I would imagine that the Whisper Controller acts in a similar manner to a MPPT charge controller for the wind turbine to give you a bit more flexibility in keeping the costs down.

For the purpose of this "experiment" you can consider the pv panel to be dumping its power into the battery, and the 40watt load to be taking its power from the battery.

What you need to be careful of is if you have no sunshine for an entire day then the 40w load will discharge your battery by 40/12 * 24 hours or 80AH. This would be a significant drain on a decent 100AH deep-cycle 12V battery.

On the other hand, if you have no load for a couple of days and your pv panel is pushing 60/15, or 4 amps continuous (with 15V being the charging voltage of the pv panel) into your battery. Once the battery is fully charged you could end up damaging your battery if you do not have a charge controller in the system.

Robert,

Maybe it is a bad or loose connection between the battery terminals and the pv panel. I would have expected that the batteries would have prevented the voltage from rising above 15V. That's why I suspected a bad battery or faulty inverter when you were able to measure 16V+ if the batteries were still connected to the pv panels. A charge controller would still be a good investment for long-term life of your batteries.

Entiendo un poco James. Solamente un poco.

Otra posibilidad para Javier es de vender el SolarWorld y utilizar el dinero para comprar más Evergreen de los mismos 180W. Eso es probablemente más barato que comprando otro controlador.

Pienso que necesitas dos controladores. Uno controlador para cada tipo de PV panel.

You will have to give us more details, but it is unlikely that there is anything wrong with your panels. A reading of 16V (open circuit) would be normal for a nominal 12V PV panel.

Connecting the PV panels directly to your batteries without a charge controller may eventually damage your batteries, but it looks to me like you just had an inverter failure.

In order to have power in the event of a grid failure you will need to have a system with battery backup. Here is a packaged system from this store.
http://store.altenergystore.com/Kits-and-Package-Deals/Grid-Tied-with-Battery-Backup/Grid-Tied-w-Battery-Backup-Package-2/p6076/

With this system you get about 600 watts of pv power for $9,000 or you pay about $15 per watt of pv power. If you go with more pv power then the price per watt will come down and should approach the $10 per watt mark for around 5000+ watts of power.

You may be able to get a grid-tied system without battery backup for as little (did I really say little?) as $6 per watt for a large system, but when the grid drops so does your pv power.

As a rough guide, multiply the number of kilowatts of pv power by 4 to see how many kilowatthours of power you will generate each day.

You probably have sticker shock to find out that it would cost your more than $60,000 (or one thousand months of utility bills) to get all of your power from pv, but at the other end of the spectrum you can probably get one solar panel, a charge controller, one deep-cycle battery, and a small modified sine wave inverter for about $1,000 that can keep your refrigerator running for months on end if you should lose power completely. You will have to look at your own budget and decide where to dive in.

When you connect panels in series, the current remains constant and the voltage goes up by the measured voltage of each panel. Thus if you had four panels rated at 7A and 12V each and joined them in series you would get 7A at 48V coming into your combiner box. If they were connected in parallel you would have 28A at 12V, so that is why each "string" of your base voltage has it own dedicated run back to the combiner box.

Stephen,

I don't know which diagram you are referring to, but all grounds, and hence negatives in a negative-ground system, have to be tied together.

A shunt is usually placed between the -ve of the battery and the rest of the -ve grounds, bus bars etc. so that you can accurately measure the current flowing into and out of the batteries using a Trimetric or similar battery monitor.

If you do not have a battery monitor then you can simply ignore the shunt.

Ronald,

What you're asking for is achievable, but give us some details on what you mean by "*very* dirty power".

I would hazard a guess that 99% of the electrical equipment in your house will work just fine (but maybe not as long!) off a cheap (<$200) 12VDC/120VAC modified sine wave inverter.

Pure sine wave inverters carry a premium price, so you want to be sure that the interference on your power is not from a source within your house before going to too much expense.

Travis,

I don't know where you live, but I believe that the black shingles also help to warm the house in the winter months for those who live at higher latitudes. Maybe a local builder could advise you on that.

I live in the tropics, and can be considered almost fanatical about keeping heat out, so I have white aluminium shingles put down on a reflective "Peel and Seal" coating.

If your black shingles are an advantage to you in the winter months, then another option would be to vent your roof in the summer months, but have it on a switch that you can turn off to keep it warm and cozy up there in the winter.

With a 30w panel it should not be a problem. Your approach is a good one, don't spend a lot of money until you're sure of what you're buying.

Gordon,

For two or more power sources to share the same load they have to be in phase. That is what grid-tie does. The best thing to do is find a small load that you can transfer to your inverter, and once you are happy with how that works then keep adding new loads until you are getting the optimum amount of power out of your inverter.

I use simple 3-way light switches with one pole connected into my main distribution panel and the other pole into a second distribution panel that is my inverter's output (mounted next to my main distribution panel on the wall). The third pole on the switch is then connected to the load (re-routed from the main distribution panel). This allows me to easily change (one load per switch!) between grid and inverter. UP for solar and DOWN for grid.

The description may sound confusing but it is really quite simple, and after a year I only need to take a glance up at the sky on any given day to know which switches I am going to throw.

If you are not going to connect your inverter to the grid then you will need a system that includes batteries.

Your math is correct. However, to get 600 watts of power from the alternator, the wind turbine that you are using to turn the alternator must be capable of generating in excess of 600 watts of power. The maximum power of a wind turbine is determined by the swept area of the blades and wind speed. Any other inefficiencies in your system will bring the total power generated down, so don't be surprised if you build a wind turbine capable of generating only 50 watts of power and it fails to deliver the power you might have expected out of the other end of your 600 watt alternator. Here is a good place to read about wind power:
http://www.awea.org/

Jerry,

I use a single 3' x 7' AET flat panel. Evacuated tubes are more efficient (and expensive!), but when you live in the tropics there is not a great deal of need for hot water. Other than the washing machine and dishwasher we could easily get by without it.

I have a single pressure/temperature relief valve installed at one end of the AET solar collector. When I first installed my system I got some air in the lines and the El Cid pump was just spinning and not actually pumping the water. After a short while the temperature reached 210F and the valve opened up spraying hot water everywhere. Luckily nobody was near it. This also cleared the air out of the lines and it has not given a single problem since the day that I installed it.

You might want to run a piece of hose from the pressure/temperature relief valve into a gutter to avoid a similar problem.

The El Cid pump is very quiet and you almost have to put your ear next to it to hear it running, although it does have small led lights to indicate that it is on. If you can hear the pump (as I now know!) then it has air in it and you are probably looking at the situation described above.

My system just circulates water from the hot water storage tank through the collector so it is a very simple setup, whereas you will probably need some sort of heat exchanger and also have to take freezing temperatures into consideration.

Jerry,

I've been using an El Cid to circulate water here in the Cayman Islands for over a year and it works great. I pump using PV power only, and in my case I have found that it works best to use only the 10 watt panel that is matched to the pump. When the sun is shining bright and the water is hottest then the pump is operating at max throughput, and on cloudy days when the panel gets shaded and the water not so hot, the pump circulates the water much slower.

I haven't purchased any yet, but in your case I would recommend a couple of sensors and a temperature differential switch to prevent the water from circulating early in the morning before it has heated up, and again late in the evening after the sun has stopped heating the water but is still light enough for the PV to operate the pump.

John

Keith,

One easy test would be to unplug the charger after the battery is fully charged, but leave the battery in the charging cradle. If your battery discharges overnight without any use then leaving it plugged in with a timer is not doing you any good. I think the instructions on some of the cheaper B&D models actually tell you to remove the battery from the charger after the battery is fully charged. This is usually indicated by the light changing from red to green. If the instructions for your chargers do not specifically tell you to remove the batteries after charging then you might be OK with what you are doing.

The 3-stage chargers that John D mentioned are the best. I have a Makita 18V cordless drill and that can be left plugged in at all times because the charger is a 3-stage model. After the battery is fully charged the light on the battery charger switches to blinking green and very little energy is being consumed. I was a bit reluctant to purchase it because of the higher price, but in the two years that I have been using it I probably would have gone through 2 or 3 B&D cordless drills.

John

Rich,

Never mind that I can't find the batteries, I just wanted to know what the ampere hour rating was for them, and I certainly would be interested to know what you paid for them. However, I still don't understand why an El Paso business would have their phone answered in Illinois? I might be coming to El Paso and just wanted to know if I could take a drive by and have a look at your WindMaster?

You can email me directly at jbodden @ candw.ky if you don't want to post your home address on this message board.

John

Keith,

I believe the Intermatic electronic timers draw less than 3 watts, and they should be available at your local hardware store.
http://www.intermatic.com/

You just need to make sure that your chargers have good diodes to prevent the batteries from discharging back through the charger when the power is switched off.


John

If you're getting 25 kilowatt hours of energy out of them I might be interested. lol.

I have 8 Concorde PVX-1080T 12V 108 A-H deep cycle solar batteries.

108 ampere hours at 12 volts is 1294 watt hours or 1.294 kilowatt hours at 120V ac without taking any losses into consideration. Eight of them thus gives me 8 x 1.294 or around 10 kilowatt hours of storage.

My electrical usage is a bit less than yours at around 600 kilowatt hours per month or 20 kilowatt hours per day.

I ran my house overnight (without A/C loads) off the batteries to test how long it would go on fully charged batteries after a long day of sunshine and my inverter cut out due to low voltage when the batteries reached 42V about 5am the following morning.

I would estimate that my 8 expensive Concorde deep cycle solar batteries will give me about 5 kilowatt hours before failing, so if you can get four or five times the amount of energy from the "worst possible deep cycle batteries" from Sears them I sure am interested in them.

John

Rich, I'm having a hard time getting the numbers that you have given me to add up. I'm not aware of any Sears DieHard battery that is 6V or any voltage other than 12V. Golf cart batteries are usually 36V or 48V.


Get a good meter so that you can be confident of your readings when you show a customer something.


820 KWH's per month is between 25 and 30 kwh per day that you are using. For easy math let's use 24 kwh for what you are getting from a charged battery. That would be 1000 ampere hours (24,000 watt hours divided by 24 volts) from four batteries at 24V, or 4000 ampere hours at 6v. That means that each 6V battery is a 1000 ampere hour battery minimum, or say 2000 ampere hours if you only discharge your batteries by 50%.

Those would be some massive batteries!!!!!!!!!!!

I know that you are in El Paso, but the telephone number on your website is area code 309 which is in Peoria, Illinois. Can I call you in El Paso to get some more details on exactly what you have and what you think it is producing?

John