I extended my solar station

Since several years ago I'm experimenting with solar power at my house.
Until a months ago I had 18 solar panels of 18W peak, "looking" to the North East (South Hemisphere) to take advantage of the morning sun (Say, now in summer, from 7AM to 14AM), to recharge the batteries of the night discharge of the refrigerator, lights and some minor power demands from it.
But I also wanted to improve the charging time over the afternoon. So, I decided to add 6 more solar cells identical to those that are currently in service, and reserved space for 3 more that are brought but not yet installed. So, actually I have 24 units operating. The new ones starts their production from about 12AM and decays well over the 7PM. The are installed in the same place than the others, but at right angle respect to the firsts, and so looking to the North West. So, in place of have too high current downloading from them, I have about the same as before, but extended in time, which is best in my opinion. Voltage in the batteries at the morning previously to the regulator to start charging, confirms it.

Then, my refrigerator, part of the indoor lightning, my ham radio station (partially but including packet radio modem and mic preamp), the wireless phone base, and the weather station base (USB step down regulator in the middle) are powered from them.

I'm very satisfied with the progress. Those that originally started as a game, now is reality and a must, because power grid shutdowns here are very frequent and sometimes, extended in time.

The regulator in the black box with the ammeter (actually a 1mA unit shunted to 10A) and the voltmeter, is a switching type, made with two complete discrete SMPS's running at 100KHz but 180 deg out of phase. As solar cells are basically current sources, I need a sort of converter from high resistance source to low resistance load (Batteries). The buck regulator is capable of making the job, and the use of two units in counter phase enhances the current handling capabilities at the same time that lower ripple is obtained.

I avoided under any case the use of movable parts as they are naturally weak and beyond the scope of my knowledge. So the static solution is my election. The only maintenance they need is to clean them with a wet rag to get rid of dust and bird feces.
 

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PRR

Member
Paid Member
2003-06-12 7:04 pm
Maine USA
That's a water tank on your roof!!

Yes, I know many people do that. Here, 7 months a year it would be frozen. I don't have any water less than a foot under the surface. The well pipe is buried. The sewer line is too, but if there is the least dip in it then it will freeze at the end of winter.

The solar panels look good. Here there is a lot of interest. Schools and towns contracting for panels on school buildings and also on abandoned trash dumps. They expect lower operating costs.
 
Interesting. The balance of power is moving from areas of cheap high sulpher coal, as Indiana, to areas of abundant sunshine as Morroco. I'm still paying $.172 a KWH for power that is 99.99999 % reliable, but times will change as solar panel prices plunge.
Interesting that your country is secure enough to allow such an installation w/o theft risk. Despite all the bad press you get. I can't install a diesel generator at my summer camp, it would probably be hauled away. As have numerous tractors & bulldozers in that part of the county. Pity it rains 250 days a year, else I'd look at disconnecting out there. Having a line & meter is $40 a month, & annual disconnect/reconnect is made cost prohibitive. I have to pull feed wires out of my distribution panel to prohibit theft of KWH by fishermen(?) in January. $110 electric bill in January 2 years ago when I wasn't out there.
 
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pitbul

Member
2011-07-29 9:34 am
@Osvaldo, nice dc system, I fully understand why you don't have inverters for the AC outlets.
If you have off the grid system you are not covered by regulation which is mandatory in my country for the on grid systems.
Is your charger MPPT? If not try it, I am well suprised with it.
AC system is lower in efficiency and you have to deal with the power factor to lower the battery consumption.

I have DC system with inverter for AC loads, off grid system and I lowered my consumption for 1/3. I have 1kWp solar panels and 5,7kWh battery system on 36V which will provide 2,8kWh from it (50% of discharge). Average discharge of the battery through the year is 82-90%. Life cycle of the battery depends on DOD (depth of discharge), if you discharge it more your life cycle will shorten. What type of the battery do you have?
 
That's a water tank on your roof!!

Yes, it is my reserve of water. It is a very common thing here, almost all houses has their own water tank. As in many towns, water decreases in pressure at the noon. In those days of warm climate, I don't need hot water for bathing and washing kitchen appliances. The water heats up naturally there.
 
Interesting. The balance of power is moving from areas of cheap high sulpher coal, as Indiana, to areas of abundant sunshine as Morroco. I'm still paying $.172 a KWH for power that is 99.99999 % reliable, but times will change as solar panel prices plunge.
Interesting that your country is secure enough to allow such an installation w/o theft risk. Despite all the bad press you get. I can't install a diesel generator at my summer camp, it would probably be hauled away. As have numerous tractors & bulldozers in that part of the county. Pity it rains 250 days a year, else I'd look at disconnecting out there. Having a line & meter is $40 a month, & annual disconnect/reconnect is made cost prohibitive. I have to pull feed wires out of my distribution panel to prohibit theft of KWH by fishermen(?) in January. $110 electric bill in January 2 years ago when I wasn't out there.

In fact it is not secure enough, it is secure particularly at my house because it is difficult to be in the roof, I need to do some pirouettes to be there.

It is still not legislated to return energy to the company here. But such a devices are expensive, bigger and fragile, so I never think of doing such a thing. My system is able to maintain me but I have no rest to return it to line, and then is another reason.

My actual monthly electricity bill is of about 100KW.h as I am very austere in this aspect.
 
@Osvaldo, nice dc system, I fully understand why you don't have inverters for the AC outlets.
If you have off the grid system you are not covered by regulation which is mandatory in my country for the on grid systems.
Is your charger MPPT? If not try it, I am well suprised with it.
AC system is lower in efficiency and you have to deal with the power factor to lower the battery consumption.

I have DC system with inverter for AC loads, off grid system and I lowered my consumption for 1/3. I have 1kWp solar panels and 5,7kWh battery system on 36V which will provide 2,8kWh from it (50% of discharge). Average discharge of the battery through the year is 82-90%. Life cycle of the battery depends on DOD (depth of discharge), if you discharge it more your life cycle will shorten. What type of the battery do you have?

As I said in the previous message, inverters here are expensive, electrically fragile and bigger in size. Their efficiency is naturally low and the system I installed suffices in capacity to my own use only. Over it, some non critical electric appliances like clothe washing machine drains several watts (VA in true) and need higher peaks of current to start those AC motors, and continue being outside the DC system.

If you want to know about the batteries, they are Vision CL150, and I have 7 of them, 6 in use and another idle. Each first week of the pair number months they are rotated, so always are in use.

I don't know exactly what the acronym stays for, but if as I suppose refers to those charger that searches for the best point in the curve of efficiency of the solar cells, it isn't. I believe that some kind of auto search it does, but really I didn't designed it to do such a thing. Soon I will post the schematic of the regulator, but actually I have it only in ASCII art or old DOS OrCAD formats.

I also post the solar cell labels downside of it, I forgot to do it in previous messages.
 

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For those that want to take a look to the schematic of the regulator, the below posted is a version of it made in ASCII art (as in the packet radio nets are). To properly read it, download it and open in with any kind of edit.com in CP 437 or 850 or word for windows, left click to open in mode DOS compatible (ASCII) and as it is far from perfect, it is understandable.
 

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Which kind of interference? At low frequency or hogh (PWM carrier). My eternal dude with such devices, is how they synchronize with line frequency and phase and they avoid "autosyncing" in its own phase and frequency, blowing all the power stage.

I had the opportunity of investigate 3 OMRON solar inverter of about 10KW here in the job, and then I learned why they are inherently fragile. Inverting from low voltage DC to high voltage AC is very hard job, and during a T-storm (In words of its owner) the 3 has blown completely. So, they are not for me. A not less make my own.