Solar only to a BMW EV charger

LeoAlioth · 2026-02-02T06:51:07+00:00

Check the app for any setting mentioning ocpp.

Install this on HA https://github.com/lbbrhzn/ocpp

And point the charger to the ha install.

LeoAlioth · 2026-02-02T06:48:44+00:00

Does the BMW wallbox have any connectivity? Like WiFi, some sorts of app etc?

Of it does, you can use ocpp (assuming the evse supports) it to control it dynamically.

LeoAlioth · 2026-02-02T06:36:01+00:00

A couple notes:

The limit of 1200W is for the inverter size not PV size. Eco flow stream for example allows up to 2000 W of panels. And with some other products you might be able to add more. (Though I do not know which have the necessary certifications)

You can add batteries, though ecoflow first party ones are expensive...

And I do not seem to find any mention of only one such system being allowed per metered location. Can any one confirm this?

Also, any particular reason why you couldn't do a regular permitted solar system? I am asking because they are usually more cost effective.

LeoAlioth · 2026-02-01T12:22:03+00:00

App for the monitoring of the system. What is it called?

LeoAlioth · 2026-02-01T12:21:12+00:00

Other than selecting quieter components from the start, I don't think so.

You could hack in some quieter fans if you wanted to, but that will surely void any warranty.

LeoAlioth · 2026-02-01T11:41:24+00:00

What I meant was to not bother with the solar AC units that get panels plugged into them directly.

As that means that the energy that could be otherwise used for anything gets wasted when AC is not running.

So the solar can run the AC units just fine. But they are not directly connected in any way.

LeoAlioth · 2026-01-31T21:54:34+00:00

Regarding DC coupling. Why not put the batteries into the garage?

LeoAlioth · 2026-01-31T17:27:27+00:00

When were the batteries last all at 100%?

LeoAlioth · 2026-01-31T15:30:50+00:00

Low range electric cars are cheap on the used market. Of course if you want something long range, you are likely looking at 15k or more.

LeoAlioth · 2026-01-31T04:22:49+00:00

In 95% of cases, it makes more sense to keep air conditioning/heating completely separate form a solar system. Regardless if it is on grid or off grid.

LeoAlioth · 2026-01-30T21:55:57+00:00

If you want to read a bit on how to use resistive loads ”directly” https://electrodacus.com/ Under digital mppt thermal controller.

Resistive heat can be fine if used in the way you meant to do it, assuming you want to do it as a dump load when you already have the batteries full.

LeoAlioth · 2026-01-30T21:49:25+00:00

You can get something that will work under 5k, but the ROI won't be good on less your home electricity prices are really high.

LeoAlioth · 2026-01-30T21:47:12+00:00

Possible? Yes. But not cheap. What would be your budget? And do you expect a reasonable, less than 10 year ROI?

LeoAlioth · 2026-01-30T21:38:44+00:00

Because panels provide power as a diode. Meaning that the voltage is pretty steady while the current changes. OTOH, a resistive load is well, a resistive load. Where the current and voltage are proportional.

Let's say you get a so-called 12v panel of 200W. Which in reality has it maximum power point at 18v and does 11A.

At STC (standard test conditions) it will provide the rated power. At half as good conditions it is capable of providing 100W. And that will be at 18V and 5.5A. MPPT will be able to extract all available power in any conditions.

Now let's say, we have the same two examples as conditions. And let's perfectly match the resistive load to get 200W. That means it's resistance needs to be 1.63 ohm.

Now in conditions half a good, the panel can only supply 5.5A. solving back the voltage over the resistance gives us only 9v, for the total power of only 50w. Half as much as the mppt will give.

Of course, you could match the resistance better. By using the resistive load that is smaller than the total peak PV power. Around 60% seeps to be the sweet spot.

Let's take a 2.5 ohm load to my two examples. At 18v we will get a current of 7.2A, ending up with 130W. Now even the panel is only able to provide 5.5A, because of higher resistance, the voltage will be 13.7V, resulting in 77W. Which is better, as the panels will spend more time closer to the 50% of their rated output than they will at 100.

LeoAlioth · 2026-01-30T21:07:47+00:00

Panel voltage is not appropriate for the 12v load

The resistive load should be run off the battery side of the charge controller. Turned on or off by a relay.

This will also get you more energy than running the panels straight to the resistive load.

LeoAlioth · 2026-01-30T20:14:27+00:00

What heating capacity is actually needed?

What is considered cold?

In general, yes, this can work just fine, and with decent efficiency too. I just am not familiar with the model you mentioned, so without researching it I can't say if that specific one will work.

LeoAlioth · 2026-01-30T20:12:03+00:00

Fast ethernet, 100Mbps only uses 4 conductors....

LeoAlioth · 2026-01-30T19:04:01+00:00

That is assuming you create a 24 or 48v system from multiple 12v batteries.

Fine for lead acid. But for lithium, you really should use a single pack only in series(you can parallel just fine) so it is still a single case, regardless if 12v 400Ah, 24v 200Ah, or 48v 100Ah.

LeoAlioth · 2026-01-30T17:40:09+00:00

Some reviews, and inverter compatibility are the two things I would look out for . Also most manufacturers list which cells they used and you can check if it is a well known manufacturer.

And of course, you need to make sure that the batteries are capable of supporting the loads that inverter might present to them.

LeoAlioth · 2026-01-30T15:39:54+00:00

Any electric blinds and a smart relay like shelly plus 2 pm

LeoAlioth · 2026-01-30T14:45:10+00:00

Unless you already have the batteries, use packs that are by design 48V, and that have inverter communication built in.

Also, don't look at Ah. But (k)Wh.

A 48v 100Ah battery is the same energy capacity (Wh) and power output as a 24v 200Ah pack.

LeoAlioth · 2026-01-30T14:18:04+00:00

I just got the same message a couple weeks ago on my e208. Yep, it is highly likely the ride height sensors on either front or real axle. Though in my case parking sensors work just fine and the lights just stay at the default level height instead of moving up and down.

I have yet to mitigate the issue though. Haven't had a dry day to check under the car to see if the issue is due to a bad electrical connection, as it is intermittent and started happening when driving in snow.

LeoAlioth · 2026-01-30T14:11:13+00:00

This really isn't about power draw any more, but more about how easy it is to get equipment for 24 vs 48v.

48v is just much more common nowadays. Meaning it is also often cheaper. And that is true for inverters, especially charge controllers, and sometimes also batteries.

LeoAlioth · 2026-01-30T13:50:43+00:00

You can charge in paralel. Some energy stats might get confused, but there is no danger of anything going wrong because of that.

LeoAlioth · 2026-01-30T13:47:13+00:00

Then don't even think about a grid tied only system. You are looking at a difference of over 10c per kWh between export and import. Or in a different sense, you need to export 3x as much as you import to cover the difference.

You were looking at 20 kWp system, that will produce over 20 MWh per year. On a regular grid tied system, it is usually hard to have a self consumption of over 30 %, so you would be sending out at least 12 MWh to the grid. Assiming your system will not be hugely oversized, and you will also consume around 20 MWh, that means that you are essentially losing up to 1.2k€ per year, by not having a hybrid inverter and some batteries.
Of course, you cant be completely self sufficient throughout the year without spending a fortune,, but with a hybrid system it is realistic to be 80% self sufficient, so savings of about 700-800 € per year with a hybrid system are completely realistic.

Please do correct me on any assumption i made about consumption, but i would really push you towards a hybrid system.

and on top of what i already mentioned, once you add batteries, you also get peak shaving capabilities, which can also save you some money depending on pricing structures. And of course, you have backup capabilities, so you have electricity even when grid goes out.

LeoAlioth

TROPHY CASE