Solar That Really Works

[pkmesser]

Originally Posted by Nuge

Now I'm wondering if an alternator driven by an electric motor powered by your generator might be a little more efficient and quicker way to get an occasional charge??

If you are thinking of efficiency in terms of power conversion, this isn't too good, if you are relateing it to the time it takes to charge the battery pack, then it would be. I thought about this back in the late 80's with a prior MH, but decided not to because of the space it would take up.
For a 130 amp alternator, you would need a minimum of a 2.5 hp motor.
And then get the belt sheves correct for a proper alternator speed.

[Kathy_MD]

Originally Posted by Happycarz

Kathy,
I, like you, have 405 watts of solar and 440 ah of storage and, since following Handy Bob's guidelines on setting up the solar correctly, the solar now brings my battery bank up 100% by early afternoon. I used to bulk charge my batteries and the let the solar finish. Not anymore. I used always start the generator to use the microwave. But now if I'm heating something for 2 minutes or less, I just use the inverter.
You may not have as much sun as I do, so your results may differ.

Happy, I have my panels mounted flat and, based on my locations, I most likely get less sun-hour than you. Also, my power use is based on years of being spoiled. I like my hair blower, curling iron, microwave, wide-screen TV, DirecTV, cappuccino machine, blender and other absolute necessities of life.

After reading Handy Bob's blog (thank you sir), I decided to put a 50amp switch in-line for the solar. I take the solar off-line before starting the genset. Now, when I start up the genset the PD charger/converter is not tricked into going to float stage early due to the solar input. Although I do not get the 14.8 I want, I do get 14.4 for the duration of genset run. When the genset run is over ( based on the converter going to float or alloted time for genset running allowed at campsite is over - whichever comes first), I switch the solar panels on-line to finish the job.

So far, so good. Not THE perfect solution, but better.

I'm working up a circuit to do this automatically. Upon genset start (run position), a 40 amp DC relay(normally closed) will open and drop-out the solar panels before the converter comes on-line since there is a built in delay on the genset output. Simple circuit really.

My preferred solution is to get a Magnum Converter/Charger/Inverter because it is adjustable. But right now the price of that unit severely eats into my shoe budget. I have my priorities.

Even with the Magnum, I would still keep the solar drop-out circuit in place so the Magnum is not tricked.

[Happycarz]

I will be boondocking Friday - Tuesday and will see how much power I can use. As I redid the solar in December, Quartzsite in January was my first trial. I used the generator for long meals in the convection/microwave. Other than that, I didn't try to conserve. Well, maybe a little.
The big factor was replacing 10 ga wires with 4 ga and moving the controller to within 3' of the batteries. And eliminating 10' of wiring. Then I set it up to charge at 14.8v. Now the battery specific gravity is 1.300 instead of 1.250. In the morning I am only down 30%. (70% remaining) Sometimes 35%
My panels are flat on the roof also and I've seen 23 amps going into the batteries with my setup, a Blue Sky 2512ix with IPN Pro remote. I'm happy.

[Kathy_MD]

Happy, base on the Lat of Quartzsite, and taking into consideration your panels are flat mounted (computing cosine effect), I can see where you are getting plenty of power. This time of month in that location with 405 watts of panels should yield you about 170+ ah per day (theoretically) and 23A out of your panels at noon makes perfect sense. You have an efficient set-up. Az and Solar were made for each other. Heck, even in mid January at Quartzsite your set-up should be giving you 85+ Ah per day (theoretically).

I only boondock in the spring and fall and at a higher lat (44deg) my flat mounted panels are not as efficient as yours due to location. If I see 140+ ah per day (and about 18A at noon) then it is a good day. For me, the theoretical(computationally derived) power available is within 2% of what I am actually getting. I could tilt or add another panel. Tilting is out..not gonna climb up to do that. I might add another $350 (135w) panel to compensate for the location (lat) loss. My solar wiring effeciency is 1.8% loss at 50% battery SOC and improves to 1.5% loss at 14.8V. Thoses losses are at optimal output (that I never see) so my actual % loss is about 1%. Because my run (12ft) is short, I used #6 thick strand from panels to controller, then #2 to for the short run (16") to the batteries.

[Happycarz]

I go to QZ only in January with a Monaco group, while the RV show is in progress. Not a comfortable place to be this time of year. The past 4 days I was in Happy Jack, AZ (34.684993,-111.414435) in the pine trees, with afternoon thunder storms.

As, my batteries weren't charging up as rapidly as in the past, I had to think for a minute. Hmmm, I have a BIRD system to tie my coach and chassis batteries together while charging. I had forgotten to interrupt the BIRD circuit so the coach batteries would be the only ones on the solar. Once separated, I was charged 100% by noon (the last two days.)

So, I didn't get to put my system to the real test this trip, as I ran the generator for microwave use and charging in the A.M., until today. This morning when I awoke, I was at 83%.

With both battery banks tied together, I was in the mid 90's, percentage wise. I wanted to see 100% each day. I'll just have to remember to isolate the battery banks from now on.

[Kathy_MD]

Harry, Thanks for that little tidbit.
I was wondering about the occasional clicking from my battery control center. It was the BIRD kicking in. From the documentation, when ever the BCC/BIRD senses that either of the charging circuits is above 13.1V for more than 14 seconds, the BIRD will engage to charge both batteries (ties them together via a solenoid). Since your post, I have installed a switch on my dash to control the the BIRD circuit (the side benefit is zero current draw from the BIRD sensing circuitry and the solenoid). Thanks!

[Wetboy5776]

[QUOTE=Kathy_MD;944074Tilting is out..not gonna climb up to do that..[/QUOTE]


May I suggest that instead of another panel, you start getting a return on your sizable investment....with an remote control tilting frame. They are out there, or can even be made. You can also get crank ones like your TV antenna if you wanna go cheaper. At the latitudes you boondock in, this should be option #1, IMHO.

My single 200 watt panel handles all my charging, but only because I keep it tracking the sun all day.

[Happycarz]

Westboy,
How about some pictures and links, if you have them?

[Kathy_MD]

Westboy,
I did some searching, but the ones I found (all manual) were single axis. Meaning, I would still need to climb on the roof to raise/lower and I would be required to find a site where due south was directly port or starboard of the RV. In any case, these mounts were much more than the cost of an additional panel. I am sure, if I found any, motorized or crank up mounts would cost considerably more than a panel. Your idea did cause me to dust off my CAD program and play around a bit with cranks, slides and levers. It was a fun cerebral exercise, but even if I designed the thing it would still need to be built/installed by someone other than me.

Based on my boondocking areas, I experience a 30% to 23% loss (cosine effect and sun hours) from the optimal angle with flat mounted panels during the fall and spring months. That loss can be compensated by mounting another panel.

Thanks for the suggestion. It was an idea worth some google'n.

[yyzlxo]

Hi there
I am new to this Green Energy ( Solar Power ) concept and was shocked to find out how little the Harbour Freight 45 Watt panels can do. I was given this as a gift and went ahead and , a bought a Charge controller, Inverter, and was calculating what Battery storage capacity I need together with Fuses between Solar Panels and charge controller, Charge Controller and Battery and battery to Inverter. I am not sure if one is needed between Inverter to outlets. I was planning to use this in my Camper at the cottage.

This is what I have;

1. Harbour Freight 45 Watt Solar Panels ( 3 in all ). Guess it is 15 watts per panel.
2. Royal Power 12V DC to AC 400 Watts Inverter PI-400
3.Solar Panel Charger Controller Regulator 10A 12V/24V

While trying to workout Battery and Fuses requirement, I came out with the following results which means I only have power for 1 to 2 Light Bulbs. Where am I going wrong. Could someone help me out on these figures and what Fuses I would need.

Calculations:
Appliances Watts
1 x 40 W Light Bulbs 40
315W per day 45 W panel ( 7hr Sun )

Usage watts per hour 40 watts 5 hrs a day = 200W per day/ 12 = 17 Ams/Day.
Battery size required for 7 day cycle:.

7 day 315W 2205 W hrs / 12V = 193/ 50%= 386 Amp hr battery.

Does this make sense? This kit is only for two bulbs?

Assuming these calculations are correct, I need to know what type of Fuses I would require and where can I get these from? Yes I don’t have to use Inverter in this case but since I have already bought one, I want to use AC power into the camper. This would be an experiment and if confidence builds up that may try a bigger project but seems an expensive venture.

Will appreciate help because the more I read on this subject, the more confused I am.

[John Hilley]

Originally Posted by yyzlxo

Hi there
I am new to this Green Energy ( Solar Power ) concept and was shocked to find out how little the Harbour Freight 45 Watt panels can do. I was given this as a gift and went ahead and , a bought a Charge controller, Inverter, and was calculating what Battery storage capacity I need together with Fuses between Solar Panels and charge controller, Charge Controller and Battery and battery to Inverter. I am not sure if one is needed between Inverter to outlets. I was planning to use this in my Camper at the cottage.

This is what I have;

1. Harbour Freight 45 Watt Solar Panels ( 3 in all ). Guess it is 15 watts per panel.
2. Royal Power 12V DC to AC 400 Watts Inverter PI-400
3.Solar Panel Charger Controller Regulator 10A 12V/24V

While trying to workout Battery and Fuses requirement, I came out with the following results which means I only have power for 1 to 2 Light Bulbs. Where am I going wrong. Could someone help me out on these figures and what Fuses I would need.

Calculations:
Appliances Watts
1 x 40 W Light Bulbs 40
315W per day 45 W panel ( 7hr Sun )

Usage watts per hour 40 watts 5 hrs a day = 200W per day/ 12 = 17 Ams/Day.
Battery size required for 7 day cycle:.

7 day 315W 2205 W hrs / 12V = 193/ 50%= 386 Amp hr battery.

Does this make sense? This kit is only for two bulbs?

Assuming these calculations are correct, I need to know what type of Fuses I would require and where can I get these from? Yes I don’t have to use Inverter in this case but since I have already bought one, I want to use AC power into the camper. This would be an experiment and if confidence builds up that may try a bigger project but seems an expensive venture.

Will appreciate help because the more I read on this subject, the more confused I am.

Your calculations are correct. You could help by going to LED lights. You can help your situation by adding additional panels. The Harbor Freight aren't a real good value, but you could add a 135 watt panel for $325 to $350 and still probaly use the charge controller you have. You would then have 180 watts of solar panels and close to 10 amps in full sun light. You can't really count on 7 hours of full output per day unless you move the panels to track the sun.

[Kathy_MD]

Let's go with what you have (equipment) to what you will have available at the end of the day (starting to use power).

First, lets make some assumptions that you will use adequate size wire for the distance between the panels to the controller and then from the controller to the battery. Let's assume zero loss for now - it will make this less complicated. Also, let's assume that you only want to consume the amount of power that your solar can provide back the next day.

Your panels, although they say 15 watt, are really only 15 watt under optimal conditions. Meaning, they are 15w if directly pointed at the sun...all day..tracking the sun and they are hooked to a system that is at the panel voltage (the Topray solar panel 15w is about 17v Topray is Harbor Freights supplier). Running these panels at less than their system voltage (meaning running them at 12V) will yield about .9 amps per panel, or 2.64 amps for all three. You will actually see about 32 Watts from them in optimal conditions (pointed to the sun all day and low temperature).

As to hours of sun, unless you are moving them to track the sun, you will not get this 2.64 amps every hour of sunlight. Lets assume that you only get 6 hours (rather than do a cosine loss formula because I do not know where you live).

Now, using the above you have about 15.9 amp hours (2.64 x 6 hours) available from your panels per day.

Lets say you have a 100ah 12V battery (just throwing out a battery here for this example). You want to use power from the battery at night(lights) and put it back into the battery during the day(solar).

Let's compute (hypothetically - actually all of this is hypothetically because many variables are missing) the amount power you can use from the battery during the evening (lights) so that it is equal to the power put back into the battery during the day (zero sum).

Now, lets add the battery into the system. A battery is not a perfect storage device - it takes more energy to fill it up than you can get back out. A high figure for a good battery is 98%. Now that 15.9 amp hours is down to 15.5 that you can use during the night.

You have 15.5 amp hours available per evening (see above). Lets say your inverter is relatively efficient at 90%. Meaning, that it uses 100 watts to make 90 watts. I will not include idle current usage - but be aware it exists.

A 40 watt light bulbs uses .33 amps per hour at 120V. Running it through the 90% efficient inverter, it will use 3.6 amps per hour at 12V.

Now we have 15.5 amp hours divided by 3.6 amps.

So, the bottom line is that you could use a single 40 watt light bulb for about 4 hours during the night and the solar panels would charge the battery back the next day for net zero loss.

As to fuses. For your use you are only drawing 3.6 amps, but I would fuse at 15. This would allow you to pull 100 watts or so. If you go higher than this (up to the rated output of your inverter) you will need much larger wires and fuses.

Suggestion. Using the inverter for lighting is not effecient. Using a 12V light would be more effecient. A 1142 (12v light bulb) uses about 1.44 amps per hour. You could run two of these for over 5 hours straight from the battery - no inverter loss. Even more effecient is to use LED fixtures. Using 12V LED bulbs (the 1142 types) use about a third of an amp so you could run 10 of them for 5 hours with the amp hours you have available and still be zero sum.

Hope this helps.

[yyzlxo]

Thanks John and Cathy,

Your response is excellent. Before I put extra pannels, I want to see this small project work.

Cathy you mentioned

"use adequate size wire for the distance between the panels to the controller and then from the controller to the battery"
Given my sitution what would be the adequte size wires and distance between;
1. Panels to the controllers and would I need combiners for the Panels?
2. What would be an adequte size of Fuse?
3. Distance and wire size between controller and battery.
4. Fuse size between Controller and Battery.
5. Distance and wire size between Battery and Inverter?
6. Fuse size between Battery and Inverter.
7. Do I need Fuse between Inverter and usage outlet. If so what size?
8. Finally can I put more batteries and charge all of them over longer period of time continuously and use later. What I mean is let the batteries charges for three to four weeks from Solar pannel and use most of the stored energy on weekends? What are the limitations in doing this?
Agains thank you very much for sharing your knowledge with me.
Regards
Ossie

[Kathy_MD]

If you are determined to work within the bounds of what you have, then I will suggest the following. And, we will do it with economy in mind.

1.
Get a waterproof junction box from Lowes or Home Depot. Bring all the wires into the box through waterproof connectors. Tie (crimp or wire nuts) the Negatives to Negatives and Positives to Positives. This is your combiner box.

2.
One set of wires coming out of the box above will be the one to your charge controller. Based on your amperage, you could buy a 12 AWG extension cord and use the wire. The 12 gauge would be good for 12 feet of run from the combiner to the controller with less than 1% voltage drop. Since you have less than 3 amps from the panel I recommend being very conservative with loss. Keeping the % of loss low will help you. Going into the controller, fuse the positive line from the combiner with a 5 amp fuse (this will give you a %50+ safety factor). You can get an ATP fuse holder with pigtails at an autostore. Just butt connect one of the pigtails to the plus line from the combiner and connect the other pigtail to the controller.

3.
As I stated above, 12 feet is the max I would go with #12 AWG. Extension cords are not that expensive and made for a harsh life outdoors. You can increase the distance, but to keep the voltage drop low (in this case below 1%), you would need larger (more expensive) wire. The fusing would be the same amount.

4.
From the controller to the battery. Again, keep the distance short. I will assume that your controller is a PWM (Pulse Width Modulation) charger. Simply put, it is a electronic switch that connects the solar panels to the battery for a period of time...then turns off....measures the battery....then connects the battery again. During the time it is disconnected it measures the battery voltage to determine how much to charge (basically, how long to close the switch). There is more to it than that, but that is close enough explanation. This switching and measuring happens many times a second. A short run from the controller to the battery pays dividends as well. Too long a run you are not getting all the voltage and amps (power) to the battery due to voltage drop. Again, for a short run #12AWG should be fine. Lets keep it to under 6 feet. Fuse this again at 5 amps.

5&6.
Inverters use lots of current. Lots of current requires larger conductors. For 400 watts (if you were to use it full power), it would require conductors capable of carrying 35 amps. Keep the distance to the batteries short. Let's plan for 3 feet. To carry 35 amps safely with a 1% voltage drop will require 6 guage wire. This wire is available at Lowes. It is used for low voltage wiring for landscaping and is stranded to make it easy to manipulate. Three feet will cost you less than $10. For a fuse, go to an auto store and get a MAXI fuse holder with pigtails - the bigger the wire the better and I have seen Maxi fues and pigtails with #8 wire available. The short use of a lower gauge fuse/pigtail will not affect the system. Butt connect this fuse holder to the #6 wire and put the fuse as close to the battery as possible (Safety item). Then, buy a 40amp maxi fuse for the fuse holder.

7.
The inverters in this size have internal short circuit protection. No GFI, but they will shut down.

8.
More batteries....? That depends on the batteries. In fact, I don't know how well this system will do unless I know the batteries in the system. To be honest, you are on the low side of amps when it comes to getting a deep cycle battery full up with the amount of amps in your charging budget. Your system is more of a battery maintainer than a full charger. Given enough time 3 amps will charge a bank of batteries. There is a point where the bank is using all the amps to maintain (trickle charge), with nothing left over to actually bulk charge.

Batteries will self-discharge - it is a chemistry thing going on. Normally, after a battery is charged, a maintenance charge is applied to the battery to counteract this self discharge. Some call it a trickle charge. In your case, you might have enough amperage available to charge a good size Amp Hour battery over a long time and then trickle charge it, but if you add more batteries to the string then you might only have enough current to trickle charge that bank. Like I stated. Unless I know the type and number of batteries you are going to use I am guessing and I cannot answer this question accurately.

I can approximate. Let's say you have a 150ah deep cycle 12V battery. Typically, a flooded battery loosed 4% of its Amp Hour capacity a week due to self discharge. For this 150ah battery, you loose 6ah. If you are away from you cottage for 4 weeks your batteries will have lost 24ah (meaning you now have a battery at 84% charge). To trickle (maintenance) charge you need to apply about 13.2 volts at some current. You have 6 hours of sunlight so you have enough to easily trickle charge one 150ah battery.

Another way to look at this. You are away from you cottage for 3 weeks. You have (lets average down) 15 ah per day from you solar to put into you batteries. So, 21 days at 15ah give you 315 ah to put into your battery bank. Now, this is assuming nice sunny days. You could easily install 4 deep cycle batteries (6v) 440 AH total and discharge them to 50% (no more than that - it is bad for the batteries) on you vist to the cottage. It would take two weeks to recharge (put back 220 ah) the batteries, but the last week would be on trickle charge.

There are other factors involved such as temperature, your location, battery type, weather, etc. I took none of those factors into account. Some impact the results a great deal, others not so much. But, the above should give you some guidance to explore/experiment a bit. Solar energy has a bit of black art to it. Welcome to the dark side.

And....it is Kathy....with a "K"

Good Luck