Solar Panels - Whats The Latest News?

[newhaul]

Originally Posted by funjohnson

But in any install, you're now wasting sqin to extra frame of smaller/multiple panels. There's a entire row of cells that could be in that space of two frames butted together.

Matt



Sent from my LG-V410 using Cruisers Sailing Forum mobile app

Actually matt that's not really true. The cells are 6x6 sq and the frames on the panels I use are only 1/2 inch so you would loose an inch between panels however just an example here I installed 2 of t 100 watt panels on a hard dodger one on either side of the boom and 2 more on the push pit. The larger panls would not be practical for most of my installs.

[socaldmax]

Originally Posted by newhaul

Actually its a bit different than that . 22% efficient mono panels will provide usable power earlier in the day ( lower light ) than the 17% efficient poly flexible panels . So that equates to more power produced per day . Also several small panels also reduce the effect of shading on any one panel.

??????

I'm not disputing your claim, but her quote was in reference to battery bank performance based on battery bank size vs rate of discharge. The statement is true.

Your reply was about solar panel efficiency and sizing, not battery bank sizing.

[newhaul]

Originally Posted by socaldmax

??????

I'm not disputing your claim, but her quote was in reference to battery bank performance based on battery bank size vs rate of discharge. The statement is true.

Your reply was about solar panel efficiency and sizing, not battery bank sizing.

Max if you read her other posts to put it into perspective I thought she was trying to make an analogy between that and different solar panel types and charging

[socaldmax]

Originally Posted by newhaul

Max if you read her other posts to put it into perspective I thought she was trying to make an analogy between that and different solar panel types and charging

I realize this thread is about solar panels, but her post was about battery bank size. Threads drift, people ask ancillary or tangential questions. The fact is that you did not answer her question. Your response was about solar panel size.

No big deal, just making an observation and answering her question.

[StuM]

Originally Posted by GoingWalkabout

On another thread dealing with electric motors, someone made the following statement. I haven't seen any reference material to the this claim but would sure like to understand if it is correct.

"One large bank will provide more usable power than two smaller ones. Battery output capacity drops as a function of how quickly you pull power out see Pukerts laws."

It's known as "C Rating". It is generally written as C5, C10, C20, C100 etc.
where the number is the number of hours to fully discharge the battery.

If you have a nominal 200Ah battery bank and you discharge it at 10A, it will last for about 20 hours or to put it another way, you are discharging at 1/20 th of the Amps of its rated Ah capacity. That is C20.

If you discharge it at 20A, i.e. at 1/10 of it's rate Ah that would be C10.
If you discharge it at 40A, i.e. at 1/5 of it's rate Ah that would be C5.

Battery capacities are usually stated at a C20 rate. If you discharge them faster than that, you get less Ah out of them. Discharge them slower and you get more Ah out of them.

Take for example a fairly common deep cycle 6V L16 battery which is nominally 370 Ah. Reliant L16-AGM | Trojan Battery Company That page gives the actual Ah capacity of the nominal "370Ah battery" at various discharge rates.

If you fully discharge it at 18.5A (C20), it will provide power for 20 hours and put our 370Ah.

But if you discharge it at 74A (C5), it will only put out 290Ah and last less than 4 hours, not 5.

Conversely, it you discharge it at 3.7A ( C100), it will put out 392Ah and last 106 hours.

So to go back to the original question.

Assume you have two batteries each rated at 100Ah and you have a 10Amp load.

Connect the batteries into one 200AH bank and your 10Amp load is discharging at the C20 rate and will give you 200Ah.

Run your 10Amps through one battery and you will be discharging at the C10 rate and will probably get about less than 90Ah out of it. So the two batteries only give you a total of 180Ah.

Assume you are cycling your batteries down to 50%, in the first case, you have 100Ah usable. In the second case, only 90Ah usable.

[mitiempo]

The above is correct.

A large bank is also more efficient during charging than 2 smaller banks.

Interesting point - The easiest way to improve your battery system is to make it larger. For the same load you will receive more AH than the battery's stated 20 hour amp rating. You will also discharge them less making for longer life. The longer life will be better economically even considering the cost of the extra batteries.

The following is from one of Mainesail's posts on another forum:

[Sonosailor]

I notice that Amazon now sells flexible panels by HQST, Allpowers, and Kingsolar. Anybody have a favourite? I am looking at a 100 Watt panel to supplement what I have, and make up for the slow deterioration, and something I can just stitch to my bimini. I notice that they all seem to have MC4 connectors. How do you feel about these?

[socaldmax]

Originally Posted by Sonosailor

I notice that Amazon now sells flexible panels by HQST, Allpowers, and Kingsolar. Anybody have a favourite? I am looking at a 100 Watt panel to supplement what I have, and make up for the slow deterioration, and something I can just stitch to my bimini. I notice that they all seem to have MC4 connectors. How do you feel about these?

They all seem to be using Sunpower cells. Make sure they are using the Sunpower interconnects between the cells also, that is part of the efficiency and durability of Sunpower cells. Apart from that, I'd use price and reviews to help me decide, since they all seem very similar in construction and features.

MC4 connectors are great, easy to crimp, easy to install, weather proof. They also sell combiners, etc to wire up panels in whatever configuration you like.