Hi Myles
I've been hoping for an MPPT controller that is also a diversion load controller. So I was interested to check out the Morningstar model that you linked to.
Alas, I see no MPPT claim in the their data sheet. I think you'll find this is a regular controller that does not optimise the voltage.
And if we take a look at how these diversion load controllers work, its clear that they don't modify the voltage/current coming from the solar panels. But in the other hand it can be the master controller that will care for the batteries no matter where the charge is coming from.
When running as a diversion load controller you connect solar panels, wind generators and so on direct to the battery bank without any intervening device. The diversion load controller also connects to the batteries but in parallel rather than in series with the charge sources.
The controller simply watches over the batteries and when the voltage reaches the set points it syphons off power to the diversion load, thus keeping the voltage at the required level. On Current Sunshine I use a water heater so that on those days when the batteries are charged early, I get hot water.
These controllers are good for mixed wind turbine/solar installations because they can keep full load on the wind generator even when the batteries are full.
When charge source mix also includes gensets and AC chargers this controller will continue to protect the batteries, but it will play no part in modifying the output from the charge source. You'll still be wanting to manually keep track of how much you really need to be generating.
These charge controllers could be a good way to have "belts and braces" protection for your batteries. Even with other controllers in the system, this controller keeps an overall view on things and dumps power if needed. Perhaps more important with lithium batteries where overcharge can destroy the cells.
Cheers
Chris
On 25/06/2012, at 4:44 AM, Myles Twete wrote:
Exactly… the Morningstar MPPT controller that Al installed is designed to optimally load the panels at the MPP up until the point where the battery is detected as being at its charged voltage. At that point, the MPPT controller reduces the current drawn from the panels. The controller does have diversion load capabilities built-in that allow the controller to continue to draw maximum power from the panels, but putting the power into a DC resistive "diversion load".
Further, that controller uses 4-stage charging, so if its brains determine that the CI/CV stage is done, it could well shift to FLOAT and deliver minimal amounts of electricity. Not sure how it decides that it's time to go into equalization mode.
http://www.morningstarcorp.com/en/support/library/TriStar%20Datasheet%20English.pdf
Ideally, it'd be nice if the MPPT controller could be the master and "control" the output of your alternator to only deliver what the panels cannot.
Short of that, on nice days while underway, if your panels can deliver the power you need, maybe you can switch the alternator output off.
Al- I get a similar "interaction" in running my electric boat (you know my boat J) with the EU2000i delivering power to the system. If the motor isn't drawing enough power from the pack, the power from the genset and chargers will cause the pack voltage to rise. As my Lester charger detects the voltage at the CV charge point, it backs off the current it draws, so that one could think that the genset power output is continuing at 1.6kw or so, but due to the charger's controller backing off, the output is less. In running with that genset on, I always make sure that the motor's drawing at least as much power as the genset is delivering so that the pack voltage is stable or dropping.
In case this helps-
-Myles
No comments:
Post a Comment