Solar Panels for Beginners: 60 cell vs 72 cell solar panels 

Thank you again. I now plan on watching all your videos, and getting much more *great* information about ALL things solar. Like and subscribed. ***

Agreed

Thanks so much. Let us know if you have any questions you want us to address. I'm always looking for ideas for videos and blogs.

Angela Fiebelkorn welcome dear Angela good knowlege

We have done several videos that talk about the fact that grid-tied solar goes out when the grid goes done, as well as how to add battery backup to an existing grid tied solar system. Here's one example. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-6WRLdZQeK9c.html

Hubby.......................

@@CarlosAlberto-ii1li yes, and an awesome one too! ❤️

Thank you. And you are half right, Irish/Canadian French.

Amy,you have BIG hair. Thanks.

There is a good diy green energy guide on EzBatteryKit ( . ) com that can help you save huge on batteries

Rich Machten i see your comment in almost every solar electric related video i watch

zodiacfml

Nourished by solar panels.

ElectroDacus builds a nice PWM controller for charging LFP batteries for up to 3KW of solar. However several problems arise with his comments above regarding costs, using PWM v. MPPT and Panel types. Electrodacus's comments are valid ONLY for smaller solar systems, those built and wired very close to panels, charge controllers and the batteries. Not everyone will do that. When you get above 3KW of solar his numbers don't work. For example, having MPPT controllers connected via high voltage (low cost) wiring and solar array strings many metres apart yields significant DC cable cost reductions which are not available when using PWM charge controllers in the same situation. ie many metres far away in a field. 1) Efficiency is not only about matching the output voltage of 60 cell panels to meet the limitations imposed by using PWM controllers. An MPPT charge controller allows the use of either 60 or 72 cell panels and when there is not much sun about you need every watt of power you get into your batteries. 2) Loading down a solar panel and operating it outside the manufacturers recommended maximum power point profile (whether 60 cell or 72 cell or otherwise) is just plin dumb. You are paying for capability in the panel you can never use because a PWM charge controller is too "dumb" to manage the panel properly. You don't see PWM controllers used in professionally designed systems (3KW and above) for very good technical reasons. That said, I would love to see Electrodacus design and build an MPPT version of his LFP PWM controllers. The only reason he said he did not I believe was the electronics would then have become more expensive and it would have taken him longer to design and build. With modern Off Grid solar systems (going north of 3KW of installed solar panels) just for an average house, using several high voltage panel strings coupled with an efficent DC wiring design, multiple MPPT controllers and new LFP batteries... That is the way professionals do it. PWM controllers are not used by professionals for good reasons.

So,both are right; that is what i thought; i have a 1 kw setup (at full sun...) at 24 volts (60 cells each panel) and the batteries charge well, via cheap PWMs, harnessing the panels` full Amps .

Or should I say great vid muffin top

No, you shouldn't

@@AltEStore Bwaaaahahahaha

Your expanded system would need multiple controllers managing the system. The 125W panel should stay on its own controller, and the new larger panels should have their own MPPT charge controller. If shading is not an issue, then they should be wired in series for higher voltage and lower current, thus lower voltage drop. Then the MPPT controller will drop the voltage to the correct charging voltage for the 12V battery bank. When sizing the controller, take the total watts it is controlling divided by 12V for the amps output needed. For example, if you add two 300W panels, you need 600W / 12V = at least a 50A charge controller. With the wind controller, if it is charging at a higher voltage, you may need to put in a diode to prevent backfeeding to a lower voltage charger.

​@@AltEStore That is pretty much what I thought. I don't plan on more than 300 Watts. The batteries are golf cart batteries, (Trojan t-105). Currently, the 125 Watt panel charges them up fine in the summer but when the shorter days of winter set in, I have to run supplemental charging (generator tied in that I use for cooking). Four 100 Watt 12 Volt panels would be ideal, wired for 24 Volts, 400 Watts is still close enough for my purposes, (14 Amps) I'll never see that here in reality, feeding the 30 Amp MPPT controller. The 125 Watt panel can go back on the PWM controller in parallel with the auxiliary charger. (on the inputs) I am still looking for something that can handle the voltages of the wind turbines, which get higher than 130V in high winds. I knock it down right now with a 500 Watt halogen lamp in series to limit the current but in lighter winds, it absorbs most of the power that could also go into the batteries.

ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-P3YtBrymJdA.html

Norrbob thank you. That video is for mismatched solar panels. I want to optimize output for matched solar panels

Yes. Just make sure the charge controller can handle at least 80Voc input and remember the amps the charge controlelr is rated for is the output, not the input. So if you have two 250W panels, 2x250W = 500W / 12V battery = 41A output. So the charge controller has to handle at least 40A.

altE Thank you, didn't know it related to output amps, very helpful. Have subbed 👍🏼

Sorry, we haven't seen the specs for the transparent cells, so don't really know. It's important to remember that a lot of the cool new technologies you read about are either still in development, or so inefficient it doesn't make financial sense yet. But work goes on, they'll get there.

+Chris DIYer Anything you can do to keep the connections to the battery strings the same, thus provide even charging and discharging, is a good thing.

Thanks.

yep...the hair's hot

Exactly, that is the setup i have,works well.

While you technically can charge a 24V battery with a 20V panel, it is not a good option. When it gets hot, the voltage of the solar panel drops, so in the summer or any hot weather, you may not have a high enough voltage to completely charge the battery. That can cause the battery to be in a partial state of charge for months, which is not healthy for most lead acid batteries. Keep in mind a 12V panel has 36 cells, and a Voc of around 22V. So a panel to charge a battery voltage twice as high should have twice the cells and twice the voltage, thus the 24V 72 cell panels. You can see a demo of it here, ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-4hU6FUiFI2I.html

Great, the 36 cell panel is a 12V panel, designed to charge 12V battery banks. If you need more than one panel, then wire them in parallel to increase the amps. To determine if your PWM charge controller is big enough for the panels. Look at the Short Circuit Current (Isc) of the panels you are using, and multiply it by the number of panels, times 1.25 for safety. So if your panels have an Isc of 8A, and you are using 3 panels, that is 8A x 3 x 1.25 = 30A charge controller needed.

+Maxid1 One of our most popular videos is on the differencees between mono and poly. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-TCq0K3DlFdc.html However, for such a small system as yours, I would not concern myself with it. The difference is going to be so small, just get whatever panel you can get that fits, don't worry abut mono vs poly. An MPPT charge controller will likely be able to generate more power for you, but make sure you use panels that are very similar to each other. An MPPT charge controller works best when the panels are similar. If you are planning on replacing your battery bank, I suggest getting higher amp hour batteries to minimize the number of parallel strings. It is much better to wire batteries in series than parallel, due to uneven charging and discharging of parallel strings. For example, it is better to wire two 6V batteries in series than two 12V batteries in parallel. Also be careful about adding too many batteries and not enough solar to fully charge them. If you don't have enough solar, you may end up with the batteries in a partial state of charge, shortening their life. I wouldn't go much bigger than a 400Ah battery bank with 390W of solar, unless you are going for days without using it, and you have multiple days to fill the batteries back up.

Here, waiting for you to find us ;)

A 30W solar panel would most likely be a 36 cell 12V panel.

Terrific. Keep in mind you also have the option of wiring two 36 cell, 12V panel in series to make the 24V. Sometimes that works out better space-wise, if you need to work around a skylight or AC unit. Also shipping a 72 cell panel can be expensive, as it has to go by truck. Another thing to think about is not overpowering the batteries. Most batteries like being charged at about a C-10 rate (plus or minus a couple), which means, for example, if you have four 12V 125Ah batteries wired in series/parallel, you would have 24V 250Ah. You should aim to charge it at about 25A. 25A x 24V = 600W of solar.

Come on by! We are here Monday through Friday, 9AM to 5:30PM. We don't have a storefront, but have some of our technical sales reps and lots of inventory here in Boxborough, MA. I suggest calling first just to make sure we've got what you are looking for in stock, and have someone ready for you. 877-878-4060.

We currently have a bunch of Made in USA SolarWorld 325W 24V panels in stock. www.altestore.com/store/solar-panels/solarworld-325-watt-solar-panel-sunmodule-sw325-mono-v40-frame-p11919/

Thanks so much! You take the hard work out of the researching!

Totally different technology. That is molten salt, this is salt water.

I'm not sure I understand your question. Will a microinverter work at night? No, it needs the sun. Newer microinverters can be used with a battery system allowing you to use the energy made at night. www.altestore.com/store/deep-cycle-batteries/lithium-batteries/enphase-energy-ensemble-energy-storage-system-p41457/#ENPENCHARGE10

+Adrian Cheudan That can be normal. Some installers will sort their panels as they come off the truck to make sure that they are closely matched per string. But don't worry too much about it. When calculating the expected output from a solar system, mismatched panels are factored in, so don't worry that 2 of them are 5% lower voltage, they should be fine. I suggest you also test the amps out of each with an amp meter and compare with rated Isc, but that should be don't with them facing the sun and at mid day on a sunny day. That will give you a good idea if the panels have a problem.