Help with using Sharp solar panels in series

[catokus]

I'm installing a automatic gate opener that runs 24 volts. I'd like to use 3 Sharp solar panels that I already own and I'm hoping that someone can help me with the configuration. The panels I have are Sharp ND-62RU1 they are 62 watts with a maximum power voltage of 8.61volts. Can I series three of these together for a 24volt system. Also does anyone know where I can get adapters for the end of the wires that come off the panels. I have photos of theseSharpsolar.JPGphoto.JPG

any help would be appreciated
matthew at morrisdrums.com

Mod note - I broke the link - email addresses on forums can sometimes get you buried in spam. Best to put the email in your profile and note where it can be found in your post. One of the guys who ca help should be around before long.

Russ

[Sunking]

No you cannot use them for a 24 volt battery system. You need never be able to fully charge the batteries.

[Mike90250]

You need 28 - 30 Volts to force a charge into the batteries. Try looking for another matching panel, or sell those to buy the correct voltage panel.
An MPPT charge controller can "downconvert" 40-60V panels to 24v charging, sometimes the oddball voltages are less expensive - but made up for by the expensive controller needed to use them.

Nasty pickle to be in.
- from email address - you make / sell Morris Dance drums ?

[catokus]

If I were to get another panel would they work

No you cannot use them for a 24 volt battery system. You need never be able to fully charge the batteries.

If I were to get another panel would they work? I can get two more if they would work.

[Sunking]

You only need 1 more to make it work. You want Vmp between 32 and 36 volts if using a PWM controller. If using MPPT anywhere from 30 to 130 volts will work.

[catokus]

what type of charge controller would I need

Thanks again for your information. Would I need a charge controller and if so what type and size would I need? Also where would I be able to purchase one?

[catokus]

Controller type?

What is the difference between a MPPT and a PWM controller?

Drums are a hobby of mine.

Thanks in advance

You need 28 - 30 Volts to force a charge into the batteries. Try looking for another matching panel, or sell those to buy the correct voltage panel.
An MPPT charge controller can "downconvert" 40-60V panels to 24v charging, sometimes the oddball voltages are less expensive - but made up for by the expensive controller needed to use them.

Nasty pickle to be in.
- from email address - you make / sell Morris Dance drums ?

[Mike90250]

You will need a charge controller, and if you are in Bakersfield, then I'd suggest you FIRST plan out how you will mount the solar panels. You will need at least 4 to get you to 34V, and 5:42V, 6:51V.

At 34V, you will only have about 1.8A to charge with. I don't know the load of the motor, how often it runs, or the size of your battery. If you are using 2, "box store" 12V marine batteries, they are about 85AH , so you "should" have an 4-10 amp charge source. 6 panels at 51V, with an MPPT controller, would give you about 2 amps, which "might" be barely enough to keep the batteries topped off. If you have a lot of nighttime usage, you might not get a full top off daily, and eventually ruin the batteries.

The Morningstar SunSaver MPPT-15 has an input limit of 75V. Your panels have a 10.8v open circuit voltage, 7 panels would put you over the threshold of "Controller Kill".

I'd feel comfortable of suggesting 6A, @ 28V (charging voltage) which is about 200w of panels, after you derate the "loss" from factory Factory specs (STC) to real life usage (like the EPA mileage sticker on a car - right!) So look for a 200W panel, in the 45-60V (beware the open voltage spec - no higher than 70V - you don't want a cold morning to zap the works) range. Easier to mount 1 panel, than 5 or 6 little ones. (depending on how clever you are)

[Sunking]

Yes you will need at least a 10 amp controller available from many distributors. Look for MorningStar Sun Saver Controller

What size battery are you going to use.

[Mike90250]

What is the difference between a MPPT and a PWM controller?

From our host's webstore:

http://www.solartown.com/store/catalog/charge-controllers/

Pulse width modulation (PWM) charge controllers send short charging pulses to the battery to detect the state of the battery. This allows the system to determine how fast energy should be sent to the battery and how wide the pulses should be.
(efficiency can range from 90-10%, depending on how well you match the panels to the battery)

Maximum power point tracking (MPPT) charge controllers will convert a higher voltage DC solar panel output down to a lower voltage needed for charging batteries. Constantly monitoring both the solar panels and the battery, solar MPPT charger controllers help you optimize your energy collection. (efficiency about 95-97%)

[catokus]

What about an inexpensive charge controller

What about an inexpensive charge controller like the chinese ones on ebay. I found one that looks to me to have similar specs to the morningstar but alot less money? Are they crap? here is what is listed.

SOLAR ENGINE MPPT 15A 12V/24V Charge Controller

Output 10 to 30% more power than regular controller

SOLAR ENGINE-MPPT solar controller can intelligently regulate the working voltage of solar panels, letting the solar panels always work at the Maximum Power Point of the I-V curve. Compared with ordinary solar controllers, this MPPT controller can increase the efficiency of PV modules by 10-30%.



MPPT advantage:

The Maximum Power Point Tracking (MPPT in short) system is a system that allows PV panels to output more power by adjusting the working conditions of the electrical module.



Product features:

Applicable to various types of batteries,

MPPT function

Microprocessor controller pulse width modulation (PWM) charging

Temperature sensor battery charging compensation

Overload protection (automatic restoration)

Overcharge protection

Short circuit protection (automatic restoration) ,

Thunder protection

Reverse discharge protection

Reverse polarity connection protection (automatic restoration)

Under voltage protection

MPPT principle:

The ambient temperature and the intensity of sunshine mainly affect the maximum power point. If the intensity of the sun is constant, the maximum output power decreases with the rise of the temperature. If the temperature is constant while the sun intensifies, the open circuit voltage of PV battery basically is unchanged, but the short circuit current increases substantially, thus the maximum output power increases substantially.

This SOLAR ENGINE-MPPT solar controller can intelligently regulate the working voltage of solar panels, letting the solar panels always work at the Maximum Power Point of the I-V curve. Compared with ordinary solar controllers, this MPPT controller can increase the efficiency of PV modules by about 30%.

However, due to many different factors, such as the difference in solar panel making, the change in the sun

[catokus]

Charge controllers

From our host's webstore:

http://www.solartown.com/store/catalog/charge-controllers/

Pulse width modulation (PWM) charge controllers send short charging pulses to the battery to detect the state of the battery. This allows the system to determine how fast energy should be sent to the battery and how wide the pulses should be.
(efficiency can range from 90-10%, depending on how well you match the panels to the battery)

Maximum power point tracking (MPPT) charge controllers will convert a higher voltage DC solar panel output down to a lower voltage needed for charging batteries. Constantly monitoring both the solar panels and the battery, solar MPPT charger controllers help you optimize your energy collection. (efficiency about 95-97%)

Is it worth spending the extra money on a MPPT controller. I'd like to mount the 4 or 5 panels I have access too on a mount that I will weld up of angle iron. The square mount with the panels will then be welded to a pole at the proper angle about 8 to 10 foot in the air.The gate opener that this will run will only be used a few times a day and probally will never be used in the night. I plan on using just 2 deep cycle marine batteries from a box store. with that information I'd appreciate any guidance. I'd like to spend as little as possible, but I would rather over engineer the system and not have any long term problems. So if that means me spending a little more for a MPPT charge controller I'd do it. I'd also like to know if using the cheap chinese controllers are a bad idea or not. It looks like I'll be using the 5 Sharp panels together in the mount.

Thanks

Matt

[Mike90250]

I'd say avoid the SOLAR ENGINE. It does not list an MPPT efficiency spec, and is most likely a fake.

But as I pointed out, even with 6 panels, you won't even have 2 amps, which may not keep up with self discharge over time - you only have 3 or 4 sun hours in the winter months. I think selling the ones you have, and getting a 200W panel of enough voltage, will serve you OK. I also know most gate openers have small 40ah 12V batteries, with a 60w panel, which works with the small batteries. With the 2 large batteries - you have more losses (self discharge) to make up for.

[Sunking]

Mike maybe I am missing something here, and is why I asked the OP what size battery he has.

Point I am making is he has 60 watt panels rated at 8 volts. That means just over 7 amps in series. With a total of 240 watts is enough to maintain a 24 volt battery @ 100 AH.

[Mike90250]

I plan on using just 2 deep cycle marine batteries from a box store. with that information I'd appreciate any guidance.

I'm guessing these are about 85ah batteries. 2 in series gives 24V @ 85ah
5-10% of capacity as charge would be about 4-8A at 28V (or 112w - 224w)
4, 62W panels = 248w x 80% =198.4w @ 28V = 7a of charge.

I have no idea where my brain was earlier today. Thanks for the sanity check Sunking.