Author Topic: Hybrid solar / wind and dumpload (Read 5061 times)

Rover · « **on:** February 22, 2009, 06:03:04 PM »

This may have been answered somewhere else, but here is the issue..

I have 300 W (rated) solar panels contorlled by a Blue Sky MPPT 25 amp controller, and 2 wind turbines , that are rectified and then dumped directly to the batteries. (system is 12 v)

I have a homemade monitoring system that measures amps in from sources and battery voltage.

With the MPPT solar controller.. Bat voltage can go to 14+V (14 to 14.5v) ... in a float mode where current is limited. Now if I wanted to indroduce a dumpload from the batterie for the wind turbines, can I?

Would I have to set the dump voltage to > 14.5 v based on what the solar mppt controller is doing?

or is it just not possible with this setup?

tecker · « **Reply #1 on:** February 22, 2009, 01:15:44 PM »

with a full state of charge from the solar input of the controller will float there monitor as you have said .The wind generator on top of a full charge will raise the voltage fast .The solar control will drop the pulse rate . You should add a dump circuit and adjustt to cut the wind generator input and divert it to dump at what ever voltage works with it's standard work rate . At high amperage you may see voltage rise as the battery will plump up and that depends on the bank of batteries large AH batteries don't jump in voltage like car batts or SLAs

electronbaby · « **Reply #2 on:** February 22, 2009, 07:14:39 PM »

Yes, you would set the dump threshold (turn on) above your bulk PV setting. If the batteries are in an environment that gets cold, make sure you run a temp compensation on your diversion load controller, as well as your PV controller.

SparWeb · « **Reply #3 on:** February 22, 2009, 09:55:52 PM »

Something to ask just to make sure: Do you already have a second controller for the wind? Since a solar controller is free to be open-circuit with no harm, it has to a specific "diversion" capability built into it, which is a different mode of operation because with wind it must not be open-circuit. Sorry, don't know the Blue Sky specs off hand, so if it has a diversion control mode let me know.

Since the solar panels have a nameplate rating of 300W total, then at 14V you are getting, say 20+ Amps on a cold sunny day. It sounds like you're already using the MPPT controller up to its potential and a separate controller for the wind is in order.

Connecting the turbines directly to the batteries is the right way to do it. The use of a dedicated wind controller means that it is in charge of the diversion control, leaving the solar controller to do its own pulse-width modulation thing on a separate solar circuit. The diversion control monitors battery voltage and sheds current through the dump load when the voltage rises above the threshold.

Depending on how you set them, you can get into trouble if suddenly it becomes possible to shed BOTH the solar current and the wind current. This can happen if, for example, the solar controller's threshold is higher than the wind controller. The solar controller is still delivering electricity to the batteries (it thinks they aren't full yet) but as fast as it comes in, the wind controller dumps it out (it thinks they are full). If the wind is blowing, and the wind controller is only sized to dump the wind load, then it could be overloaded.

Set the wind diversion controller's dump voltage higher than the solar controller, and as already suggested, use a temperature correction on both to keep them in agreement. What kind of batteries do you have? That's important in deciding how high voltage is permitted.

Rover · « **Reply #4 on:** February 23, 2009, 04:19:41 AM »

The Blue Sky Model I have, does not have a diversion controller. The wind gens are rectified and then direct to batteries without regulation. The battery bank is 6 group 27s (115 AH) each.

I was hoping to put a dump right off the batteries as opposed to diverting the wind gens.

ghurd · « **Reply #5 on:** February 23, 2009, 05:42:05 AM »

"Diversion" controllers dump right off the batteries too.

They do not select only the power from the wind gens.

Diversion, Shunt, and Dump controllers all do the same thing. Except for some homemade circuits, and some of the goofy Oatley kits.

If the MPPT is not using temp comp, then any accurate dump controller will work fine. Set it a hair higher than the Acceptance voltage. Dump at 14.35V (?) if it is the 2512.

The automatic equalization should be disabled, and equalization will need done manually.

G-

Rover · « **Reply #6 on:** February 23, 2009, 02:44:13 PM »

Sounds good to me , it is the 2512i (not the x) so no equalization, no temp, no dump. Bought the unit a few years ago, probably should have got the 2512ix

Rover · « **Reply #7 on:** February 23, 2009, 03:47:04 PM »

...one more question, anyone see a problem with using relays activated by my homemade metering system to open the dumpload? . With a suitably sized dump load less than 30 amps (which is less than my gens have ever produced) using off the shelf 35 amp automotive relays?

ghurd · « **Reply #8 on:** February 23, 2009, 04:02:49 PM »

I am starting with an afterthought.

Almost anything with a relay is crap for what you are trying to do. An automotive grade relay will chatter itself to death in hours. A great relay will chatter itself to death in a few days.

Using a 2512iX at the shop for year and a half. Very happy with it.

Winter is evil here. Worst-case 30-day average insolation is <0.5H/D. It made a very noticable difference.

Get a simple, accurate, adjustable, single-stage, dump controller.

Set it higher than the max voltage the 2512i will reach.

"accurate, adjustable, single-stage" is a problem.

'Accurate and Adjustable' go with multiple stage controllers.

Which factory-made dump controller does that?

I have no idea.

My ghurd circuit/kit does that. The temp has a minimum effect (ZDs are C grade 5.1V {better than A grade} and {5.1 has less temp related swing}). Not perfect, but as good as it gets for that kind of money.

It is not a cheap advertisement. I simply can not think of another controller meeting the specs.

This is the shameless plug: There are assembled and calibrated ghurd circuit kits available in the US and UK from time to time (like right now).

It would need more power fets, and quite a few power resistors, but I honestly can not think of anything better.

G-

Rover · « **Reply #9 on:** February 23, 2009, 04:15:02 PM »

Nice plug..

since my metering system is based on a micro controller that will feed the trigger voltage (and I can program rewire as needed), I can't see chatter being that big of a deal (I can always be wrong). I'd even go solid state on the relays..but the $$

Rover · « **Reply #10 on:** February 23, 2009, 04:25:40 PM »

...Adding.... The meter (which will become a controller) I can program to trigger a relay for a duration(dump for say 10 to 6o minutes), and also check voltage during the duration. Since I already have current data for all sources and outputs (4 amp meters) I could also programmatically check the amps comming in, don't know if I will do that though... running short on program space.

ghurd · « **Reply #11 on:** February 23, 2009, 05:39:45 PM »

Set it a hair higher than the Acceptance voltage.

"(dump for say 10 to 6o minutes)" is not accurate or even remotely acceptable IMHO. A $30 SG-4 is 360 times per Second.

Voltage during the duration will vary wildly.

A auto relay, for say head lights, used 3 times a day for 10 years is not many cycles when compared to a accurate controller.

The 2512i runs at...?

G-

zenpi314 · « **Reply #12 on:** February 23, 2009, 05:48:52 PM »

Sorry. I don't mean to hijack the post, but could you give us some information, in a separate post, on your micro-controller metering. I'm in a similar situation as you are. I have some solar and am now finishing up on a turbine. I bought a micro controller, which will be my next project.

Nice follow up on your post. Pleasant/interesting to read.

Thanks

Arno

electronbaby · « **Reply #13 on:** February 23, 2009, 05:58:19 PM »

Glenn, The reason why I said to have temp compensation on both controllers earlier in the post is during winter months when batt temp falls, bulk voltage rises quickly. Sometimes the MPPT controllers let the bulk voltage rise super high and this will false trip your dump controller to dump not just wind, but all your PV...at the time you need it most, the coldest months. The problem comes when you have more PV and wind combined than your dump can handle. Things will surely cook. This might not effect many of the guys and gals just starting out with small systems, however, it is good to understand how batteries react in the cold and what to look out for when the size of your system starts to grow.

Rover · « **Reply #14 on:** February 23, 2009, 06:26:23 PM »

Ghurd, Honestly....no argument on the 10 60 minute thing....I know it is a horrible variance, but the goal (at least for me) is to software control the dump, with the tools I have (basic stamp bs2px).

I actually see a number of detractors from my approach that I don't know If can overcome yet, I'm a programmer by trade, but my choice of microtrollers.. although adequate has some seririous issues. Probably too many for this thread. Example, watching for the voltage drop that occurs because of the dump load, and making sure I can get an accurate v reading, influence of blue sky etc... .

For those of you watching this thread, for me it is more of a DIY hobby, please don't assume that this will relate to your efforts.

Rover · « **Reply #15 on:** February 23, 2009, 06:33:27 PM »

sure... my site is http://www.rovr1.com/wind/ ... needs way more technical detail, but you can get the drift on what I'm doing. Be aware that the site and the sytem are alway in flux as I try something differenet...

As I also posted.. I am trying things, I will fail, don't base your project on mine as any kind of absolute way of doing things, that is why I search and ask questions here.

Rover · « **Reply #16 on:** February 24, 2009, 07:03:35 AM »

Thought I'd better add an overall system diagram

ghurd · « **Reply #17 on:** February 24, 2009, 07:55:59 AM »

Our SB2512iX doesn't swing the voltage. It never goes a millivolt higher than it should. We have more battery (550) than panel (180). Batteries are in a house, no temp comp, always between 60 and 85F. I am a Big believer in temp comp, but the MPPT did more good than a temp comp controller with semi stabile bat temps.

The SB2512i has no temp comp or adjustable set points. Acceptance is 14.2V, float at 13.2V.

If a dump able to handle the windmills is set at 14.3 or 14.35V the solar controller will have stopped the amps before that, at least that's how I have it figured.

I don't know a thing about stamp. But couldn't it operate a power fet to a big fat IGBT? Get around all the relay problems.

How many amps are the windmills, and battery AH?

G-

Rover · « **Reply #18 on:** February 24, 2009, 02:58:37 PM »

Solar panels 300 w (2x 100W, 1X 55W, and the cheapo amorphous HFs at 45w) On my best days I see 16 - 17 Amps

Wind1 .. 1/2 hp ECM conversion -- Max ~ 10 amps

Wind2 .. Chinese knockof 450W rated --- Max 20 amps

My solar is the most dependable generating 10x routinely over the wind gens (bad location)

On the acceptance phase of 2512i , with my data logger I see ~ 14.3 V, with a gradually reducing curent.

I'm starting to rethink the dump, with the dump, I'm going to see a voltage drop, I'm pretty sure the 2512i could then start boosting its current to the battery in response. Oh yeah, and my batteries are located in a shed, I can have fairly high temp variance.

As far as FETs, hmm guess I'll start looking at some circuits.

birdhouse · « **Reply #19 on:** March 02, 2009, 11:15:56 PM »

interesting thread...

i'm new, and i know you want to solve your issues with programming, but am i the only one who thinks just put a dump style controller set at a higher voltage and call it done??

my2cents

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Author Topic: Hybrid solar / wind and dumpload (Read 5061 times)