question

david-mccurdy avatar image

MPPT, Lithium and dump load

I am planning a solar system for a camper van RV with with 500w solar with lithium battery storage. Once the batteries are charged, I want to use the "excess" solar (dump load) to heat water in a hot water tank.

What MTTP controllers are able to do this?

Is this advisable?

Are there recommend configurations (panel watts, controller, switches) that would make this plan a better solution?

If possible I would also like to use the power from the moving van to charge the batteries (I know I can do this part) and once charged have the water heated in this way.

Thanks in advance for your wisdom.

David

MPPT - Solar Charge Controller
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3 Answers
Johannes Boonstra (Victron Energy Staff) avatar image
Johannes Boonstra (Victron Energy Staff) answered ·

Hi all, well in short, all Victron MPPTs can switch on excess solar, how depends on the model. Beside this there are of course multiple ways which lead to the same as always.

In Ve Connect you can program the MPPT to switch the load output (if there is one) or the relay (if there is one ) or the Ve direct port (if there is one).

Sometimes the dump load is more powerful then the MPPT can switch directly, as the current is limited. So then the MPPT controls a relay on/off, and that relay controls the dump load.


Easiest way to program is to have the Ve connect controls switch the dump load ON when the battery voltage is at a level of a full battery. Beware that this can result is a on/off switching as the dump load may require to draw more power then the PV can deliver. so set the OFF voltage at just a little lower then the ON voltage. this does mean the dump load will not be on when the MPPT is in float. depending on the battery type (lithium for example) the OFF level can be set to just below float. Another way is controlling the dump load on SOC, for this a BMV is needed.

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robert-welling avatar image
robert-welling answered ·

a recent video from Victron is showing this feature, see link below


Trigger a dumpload

2 comments
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Hi Robert, I saw that video but it didn't answer the question, it just references a feature. I understand not all victron (?) controllers offer this, and the video doesn't specify which models, or demonstrate and only points you to their professional/distributor account. which is not a great. I am not exactly an electricity expert, and notice there are quite a few people seeking similar info.

That video does show how to trigger this feature which is frustrating that it would be advertised. Furthermore the "dump load" feature isn't really that. I want to trigger a load and for the power going to that load to be managed by victron to not pull my batteries out of float.

guy-b avatar image
guy-b answered ·

I am looking for exactly the same answer with 400w SP & 200ah of lithium


BUMP

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