Robin Lim's posts

Posted by Robin Lim on Oct 11, 2004 05:44 pm

#1 -  Renewable Energy > Technical Discussion: Other > Notice regarding Steca Solsum 8.8x
LAST EDITED ON Oct-11-04 AT 06:17 PM (EST)



Posted by Robin Lim on Oct 11, 2004 05:32 pm

#2 -  Renewable Energy > Technical Discussion: Other > Re: Question about using Steca Solsum 8.8 with Xantrex XPower 300 Plus

Thanks for your reply. Yes, it seem like the Solsum is a bit over protective. I got a reply from AltE folks that with my setup (21W PV US-21), I would not need a charge controller like Solsum. In fact, they said that under 40w, there is no need for it.

Anyway, I just tried to have it returned, only to be told that it cannot be returned because it is used and cannot be sold as new (even though they were going to slap on a 15% restocking fee for *new* items!)

Granted, I told them that there was a blown fuse, which is user-replaceable, but they did not want to accept that. They (the owner via Dan) said that if there was a blown fuse, even though I replace it, there could be something wrong with the device. Sad

Gee, if the fuse cannot protect the device, then what is the fuse good for anyway???

Well, I got a 115ah deep cycle marine batt hooked to my PV and XP300Plus and now everything is working fine (without the Solsum, which is sitting on the wall nevertheless).

The deep cycle batt is now kinda acting like a buffer for the current draw and charging, so that over charging (if at all) does not occur at any rate. And over discharging is also taken care of! Smiley

Well, lesson for me, do your homework before getting something from AltE. They have good service in general, and ship fast, but it appears they are sticky with returns.


Posted by Robin Lim on Oct 8, 2004 01:25 pm

#3 -  Renewable Energy > Technical Discussion: Other > Re: solar panel in a parabolic
I heard of people using mirrors to increase the intensity of sunlight shining on the PV. However, doing this may expose your PV to more sunlight than is allowed in manufacturer's specs. So you may want to experiment on a small scale before trying anything.

Others using solar trackers that automatically move the pv panels to face the sun perpendicularly to get the maximum power output from their panel. The downside is upfront cost.


Posted by Robin Lim on Oct 8, 2004 01:22 pm

#4 -  Renewable Energy > Technical Discussion: Other > Re: Solar panal
>Im doing a research on solar panal
>effects of shading as well. To
>my knowledge, there must be bypass
>diodes for shading effects but the
>theory behind, Im still not very
>sure. Whether anot they shut off,
>is it possible if there is
>a circuit breaker behind so that
>as long as the panal did
>not get the full solar rays,
>it will shut down? Anyone out
>there would like to share the
>purpose of blocking diodes and bypass
>diodes as well?

If this is not too late ...

From what I know, blocking diodes are used to prevent current backflow at night, when the PV end up becoming a load. They are sometimes built-in for some higher wattage panels but not for lower wattage ones, though they can be installed by the user between the PV (+ve output cable) and the +ve end of the battery or charge controller input... though most if not all charge controllers would have a blocking diode built in at the PV input already.

Bypass diodes are most, if not always, built-in. They link the PV panels and allow the PV to output current even when it is partially shaded. When a PV is partially shaded, the shaded cells end up having higher impedence (resistance) and would pull down the overall voltage and current. It is called "bypass" diode by virtue that the diodes allow the shaded cells to be bypassed so that the remaining unshaded cells continue to work and produce the same voltage, albeit with slightly lower current than a full unshaded PV. Although the output current is slightly lower, it is still higher than if the shaded cell is added in the loop without a bypass.

Granted, it would also depend on how the PV is being shaded. If there are 24 cells in the PV, and 12 are fully shaded, then it is considered 50% shaded right? But if all 24 cells are half shaded ... the bypass would not work at all. Since all the cells are equally hampered. In such scenario, I am not sure how well a PV with built-in bypass would outperform one without.


Posted by Robin Lim on Oct 6, 2004 09:19 pm

#5 -  Renewable Energy > Technical Discussion: Other > Re: DC timer needed
Hi all,

Not dropped in for a few days. Thanks for your links and suggestions!

PS: I couldn't find anything in Walmart ... but will try the web or home depot! Smiley


Posted by Robin Lim on Oct 6, 2004 09:17 pm

#6 -  Renewable Energy > Technical Discussion: Other > Question about using Steca Solsum 8.8 with Xantrex XPower 300 Plus
LAST EDITED ON Oct-08-04 AT 01:28 PM (EST)

(Edited to move question up)

Does the steca solsum 8.8 support AGM batteries? Specifically, I am trying to use it with Xantrex XPower 300 Plus which has a 20ah AGM batt inside. After using it for a few days, I find that the batt does not quite charge up with similar sun exposure (we get more than 8 hours of strong sunlight here in Taos) compared to when I plug in the UniSolar US-21 direct.

Does it work better with a Deep Cycle Marine battery? Or does it work with AGM batt? Or maybe not with the AGM batt *inside* the XPower 300 as it is prob connected to other circuitries and may confuse the charging circuit of the solsum 8.8?

*Background start*
I am using a Unisolar US-21 (PV) connected to a Steca solsum 8.8 (Charge controller) coupled to a Xantrex XPower 300 Plus (20ah batt inside).

I used to connect US-21 direct to the XPower via the regulated charging input (meant for AC or generator), but found that it takes too long as the internal circuits limited the charging to a 500mA current ... ie my US-21 effectively becomes a US-6!!

Connecting direct via the DC car socket made the charging complete in 4-5 hours, meaning a low batt can be charged up by noon more or less.

Then it (US-21) charge so well, I started giving me full charge most of the day, even with high usage, but I noticed that there is some sizzing sound ... meaning AGM batt could be gassing due to overcharging? So I had to monitor the charging and unplug the charging cable to prevent that.

Then I decided to hook up to a Steca Solsum 8.8 and now the batt barely charges up at all? It does reach 12.5v or so, but after short usages, solsum disconnects the load (11.8v) So effectively, now the batt seem to have lesser amperage.
*Background end*



Posted by Robin Lim on Sep 21, 2004 01:53 pm

#7 -  Renewable Energy > Technical Discussion: Other > DC timer needed

I need a DC timer for my DC appliances. Anyone knows of sites that has such products?



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