In over my head

[russ]

Just remember the warnings about the little turbine a year after installation when it has died a horrible death after all sorts of maintenance

[Tom Bradford]

OK use the wind turd. But now you have to come up with a dedicated controller and diversion load, plus tower cost.

Well we could use the Xantrex on it IF we can use a Classic on the panels. And tower costs? Yes, But if you were one of thirty odd - to some degree or another - folk depending on this network for your internet would you rather put your hand in your pocket for $100 or spend a day hauling things up to a mountaintop, chipping holes in solid rock or cutting and welding railway irons?

[Sunking]

OK use the wind turd. But now you have to come up with a dedicated controller and diversion load, plus tower cost.

[Tom Bradford]

But you can only connect panels in series if they are reasonably close (~5%) in their Imp figures. That is why you have to find out those specs (or measure them) before making any design decision.)

If you connect all of the + together and to the + of the CC, and all of the - together and to the - of the CC, you have the panels in parallel. Which will also be fine IF the Vmp of the panels are all reasonably close (again within ~5%). (For a PWM controller, voltage mismatch of panels in parallel does not make a difference since they will all end up pulled to the battery voltage at the moment anyway.

OK, took a trip to the mountaintop in search of enlightenment - a trip made even more exciting by the fact that not only does duck-hunting season open today in New Zealand, it's also the weekend of our local hunting competition. Such is my opinion of the mental-state of the testosterone-soaked who enjoy scrambling around soaking bush for two days looking to kill inoffensive beasts who only want to be left alone that I harbour serious concerns as to whether they are fully aware that deer have not yet evolved to ride quad-bikes.

Bit I survived. Here's the geeky stuff:

Panels 1 & 2:

Pmax 80W
Warranted min power 76W
Voltage (Vmp) 17.6V
Current (Imp) 4.5 A
VOC 22.1V
ISC 4.8 (? - didn't note this)
Min by-pass diode 8A
Max series fuse 20A

Panel 3:

Rated max Power 85W
Open Circuit Voltage 21.86V
Short Circuit Current 5.19A
Voltage at Pmax 17.66V
Current at Pmax (Imp) 4.82A

Presumably voltage isn't a problem as it's within 5% however you look at it. As for Imp, 105% of 4.5A = 4.725A. 95% of 4.82A = 4.579A. If that doesn't satisfy the God of electricity could we mask out one of the cells on the 85W panel ((4.82/36)*35 = 4.686 Amp which is with the 5% range) or even two of the cells ((4.82/36)*34 = 4.55A) to keep the Classic happy?

Set it on the ground somewhere and let it rot. You woul dhave to construct a tower to clear everything by about 50 feet. Then it would still be about useless. YOu could build a brand new system for what the tower will cost with money left over. .

Aren't you being perfectionist? Sure it might need to be atop a 50ft tower if you want to wring every possible watt out of it but on this site it only has to be a meter above the top of our pole and it will be the highest thing for twenty miles in any direction - the highest thing for 2,000 miles in the direction the wind comes from - and nearly 2,000 ft above almost everything. In fact if it survives it would probably meet all our power needs with buckets to spare even at 50% efficiency. It would certainly be a lot easier to stick the thing up on a guyed 4m pole than it would be to rebuild the entire solar panel frame which has to be able to hold several square meters of solar panel in some serious winds.

Nice as it would be we have to start from where we are rather than from where we'd like to be.

[Sunking]

Some follow-on: If we get this wind-turbine donated by a well-meaning member we will be required by community politics to utilise it. How would I do this?

Set it on the ground somewhere and let it rot. You woul dhave to construct a tower to clear everything by about 50 feet. Then it would still be about useless. YOu could build a brand new system for what the tower will cost with money left over. .

[Tom Bradford]

Houston, we have a problem....

Only one?

Series means that you line up all the panels (electrically) with one loose + on one end, one loose - on the other, and with the one in the middle connected + to - and - to + to the outside two. The two loose ends are now connected to the CC (Y).

And if you have four panels? The middle two connected + to - and - to + to each other with one connected + to - on one side and the other connected - to + to the outer, with the outer having one + and one - 'loose'? Jeez, what ever happened to KISS?

But you can only connect panels in series if they are reasonably close (~5%) in their Imp figures. That is why you have to find out those specs (or measure them) before making any design decision.)

Are we talking in a perfect, Valinorish world here, so that if you connect panels with more than 5 imps difference you might not get perfection but you'll still get a large chunk of something? Or will having more than 5 imps difference loose an unstoppable hoard of imps onto an unsuspecting world? And how do you measure imps?

If you connect all of the + together and to the + of the CC, and all of the - together and to the - of the CC, you have the panels in parallel. Which will also be fine IF the Vmp of the panels are all reasonably close (again within ~5%). (For a PWM controller, voltage mismatch of panels in parallel does not make a difference since they will all end up pulled to the battery voltage at the moment anyway.

So perhaps it might be better to rebuild the frame and spend $500 on another couple of 80W panels to feed the C35 than $1,100 on the Classic.

Regarding the connection of the turbine, since it is only 200W, it seems a shame to dedicate a Classic to it. And one CC cannot usually handle both wind and PV at the same time. If the C35 does not actually dump the battery voltage down to the dump load, you can probably do well enough with it for the turbine. But a lot still depends on what type of control the turbine is expecting. The CC has to act to protect the turbine as well as to charge the batteries.

The C35 has a diversion control mode which I think is what you're referring to. We'd connect the turbine and the panels directly to the batteries in parallel and the C35 sucks out of the batteries and dumps anything they can't take when they're full that panels and turbine try to feed into them. I think that's how it works. Presumably we'd need diodes on the panel input lead at least to stop the battery and turbine try to make them glow in the dark.

For proper wiring of two batteries in parallel, and a host of other good technical discussion, go to smartguage.co.uk.

Thanks. When next I feel like a bit of S&M and the wife has a headache...

[inetdog]

And a query touching on fundamentals - when you connect panels in series does it have to be AXBXCXY where Y is the controller and X is + to - and vice versa, or can it be AXY BXY CXY?

Houston, we have a problem....

Series means that you line up all the panels (electrically) with one loose + on one end, one loose - on the other, and with the one in the middle connected + to - and - to + to the outside two. The two loose ends are now connected to the CC (Y).

But you can only connect panels in series if they are reasonably close (~5%) in their Imp figures. That is why you have to find out those specs (or measure them) before making any design decision.)

If you connect all of the + together and to the + of the CC, and all of the - together and to the - of the CC, you have the panels in parallel. Which will also be fine IF the Vmp of the panels are all reasonably close (again within ~5%). (For a PWM controller, voltage mismatch of panels in parallel does not make a difference since they will all end up pulled to the battery voltage at the moment anyway.

Regarding the connection of the turbine, since it is only 200W, it seems a shame to dedicate a Classic to it. And one CC cannot usually handle both wind and PV at the same time. If the C35 does not actually dump the battery voltage down to the dump load, you can probably do well enough with it for the turbine. But a lot still depends on what type of control the turbine is expecting. The CC has to act to protect the turbine as well as to charge the batteries.

For proper wiring of two batteries in parallel, and a host of other good technical discussion, go to smartguage.co.uk.

[Tom Bradford]

I don't think a Kiwi is much interested in American Politics.
They have Middle Earth to worry about

You'd be surprised. I was exhilarated with hope when Obama was elected for the first time and my disappointment and despair at his turning out to be just a Saruman is deep. There'd be a lot less for us here in Middle Earth to worry about if you Yanks would get your act together and ride to the rescue like you did in '41.

Some follow-on: If we get this wind-turbine donated by a well-meaning member we will be required by community politics to utilise it. How would I do this? Do I:

1. just feed it in series to the Classic 'Lite' along with the panels?
2. connect it directly to the batteries, and the panels through the 'Lite'?
3. feed its output to the batteries through the shortly-to-be-redundant C35 in diversion mode, parallel to the panels and 'Lite?
4. quietly not connect it to our system at all but use it for recharging the batteries in Galadriel's vibrator?
5. other.

And a query touching on fundamentals - when you connect panels in series does it have to be AXBXCXY where Y is the controller and X is + to - and vice versa, or can it be AXY BXY CXY?

[Naptown]

That is how Obama got elected. Nothing you can do now except suffer or hope for Impeachment. Then we are stuck with JOE Blow. At least Joe would be a Lame Duck and marginalized.

I don't think a Kiwi is much interested in American Politics.
They have Middle Earth to worry about

[Sunking]

I'm sure that it is often, as in my case, just ignorance. Now that I understand the difference

That is how Obama got elected. Nothing you can do now except suffer or hope for Impeachment. Then we are stuck with JOE Blow. At least Joe would be a Lame Duck and marginalized.

[Tom Bradford]

Their answer is always the same ignorant answer:

I'm sure that it is often, as in my case, just ignorance. Now that I understand the difference I think it is worth ditching the PWM in favour of an MPPT to get the best harvest from the panels but when we were putting this site up in a hurry it seemed like the difference between PWM and MPPT - if you just read the brochure and listed to the manufacturer's pitch - was like the difference between a Honda ABC and a Suzuki XYZ, ie a drinks holder, an extra bit of chrome here and there, a smidgin of additional bird-pulling power and a couple of hundred bucks.

This has been a very useful and informative thread for me, for which I thank you.

[Sunking]

But how does that relate to your comment above - "With MPPT you must use the more expensive battery panels wired in parallel with a Vmp of approx 17 volts."

That is a typo. Should read with PWM, you must use more expensive low voltage battery panels. With MPPT you can use higher voltage less expensive GT panels.

Once panel wattage gets to about 200 watts, a MPPT system is less expensive for a given amount of energy. A 200 watt panel and 15 amp MPPT controller with 4 sun hours generate roughly 550 wh/day and cost around $475 to $500. To get the same amount of power out of a PWM and battery panels requires a 300 watt panel, 15 amp PWM controller that cost around $550 to $700.

That i swhy I give folks such hard time when they say that have a 40 amp PWM controller with say a 600 watt battery panels. Their answer is always the same ignorant answer: "I cannot afford MPPT". Truth is they wasted money and could have done the same job using a MPPT controller with GT panels like 400 watts of inexpensive GT panels and saved a few hundred dollars.

I've fallen in love with the Midnite Solar 'Classic Lite' MPPT controller - looks great, lots of how-to videos on their web-page and what looks like a great LAN monitoring facility. In our store the 150v model is rated for 96 amps and the 200v model is rated for 79 amps, at the same price. Given that either would be hardly breaking a sweat with what we'd put into it - 20 Amps - is there anything to choose between them?

Midnight Solar makes the best MPPT charge controllers hands down favorite.

[inetdog]

But how does that relate to your comment above - "With MPPT you must use the more expensive battery panels wired in parallel with a Vmp of approx 17 volts."

Small typo, I think. That should have read "Without MPPT....."

[Tom Bradford]

If you go with MPPT rewire the panels in series.

Ah. Penny drops. That's what you mean by high voltage panels, yes? And the ampherage you need from an MPPT controller relates to the amps it's putting out to the batteries at 12v rather than the amps it's receiving from the panels at a higher voltage.

But how does that relate to your comment above - "With MPPT you must use the more expensive battery panels wired in parallel with a Vmp of approx 17 volts."


I've fallen in love with the Midnite Solar 'Classic Lite' MPPT controller - looks great, lots of how-to videos on their web-page and what looks like a great LAN monitoring facility. In our store the 150v model is rated for 96 amps and the 200v model is rated for 79 amps, at the same price. Given that either would be hardly breaking a sweat with what we'd put into it - 20 Amps - is there anything to choose between them?

[Sunking]

Is there any way of finding out what their native Vmp is? If it's 17-18 volts - and I thought all 36-cell panels did that as the cells are always 0.5v

Should b eon the name plate, but if they are BP battery panels Vmp is going to be around 17 to 18 volts.

- we've 240 or 245 watts of panel so shouldn't we theoretically be OK with a MPPT controller rather than our existing PWR one?

Should work. If you go with MPPT rewire the panels in series. At 240 watt panel will require a 20 amp MPPT minimum.