Sofar ME3000SP - balancing its operation with cheap overnight tariff.

WIAWSNB

Sofar ME3000SP (V1), 10.4kWh battery, 3kW PV, and a Phev – and now going to cheap overnight leccy tariff. How do I balance this?!

Hi.

I have the above setup which worked superbly over our sunny Summer - the PVs generated
enough to run our house and car for the majority of days. Now the nights are drawing in, PV generation has obviously dropped like a stone, with even bright sunny days not covering our needs. So, I am transferring to a new leccy provider with a cheap – 6.7p/kWh – tariff between 11pm and 6am.

My intention is to use this cheap tariff to keep our Phev running, which requires around 5kWh
for each day’s use, and supply the house which will need up to, I guess, 8kWh. I’d obviously also call on the PVs as much as possible, and would leave space in both the domestic battery and Phev to use this whenever they are generating a decent amount.

Although I will be having Smart meters installed, none of my system is ‘intelligent’. Ie, the
Sofar just does what it’s programmed to do, and the Phev will be charged via a ‘granny’ and a timer overnight.

My thoughts were to set the domestic battery's max overnight Grid charge to, say, 90%, and
charge it at a gentle 3kW (which is what the Sofar is currently set at due to the PV size). This would ‘fully’ charge it in around 3 hours. With the Type2 cable, my Phev is currently charged at 2.4kW, and I’m happy with that – it would receive its daily need in just over two overnight hours.

Any PV generation the following day would complete the battery top-up to 100%, and provide for the house’s running, or top-up the Phev a bit more.

Does that sound all fine? Have I misunderstood anything, or missed summat out?

Ok, my main Q is – during the overnight charge period, how do I prevent the charging Phev, or say a washing machine, from draining the domestic battery via the Sofar?

Many thanks 🙂

QrizB

I'm in a similar position - EV tariff, solar PV, Sofar ME3000SP, battery - and here's what I do.

My Sofar operates in time-of-use mode (chosen from the "work mode" menu). I've set it to charge to 90% overnight from (in my case, on IOG) 2332-0528. The odd 2 minutes at each end is because my Sofar clock drifts, with me resetting it each time we switch from GMT to BST and back.

Ok, my main Q is – during the overnight charge period, how do I prevent the charging Phev, or say a washing machine, from draining the domestic battery via the Sofar?

Being in ToU mode, any other loads during that period are served from the grid, not from the battery. So there's no way for anything to drain the battery during the cheap-rate period.

Edit: I should add that I've been running in this same mode all year, since my 12p export tariff pays more than the 8p-or-less that IOG import costs, and so it's been better (cheaper) to fill the battery overnight then sell the solar in the daytime.

WIAWSNB

https://forums.moneysavingexpert.com/discussion/comment/82190475#Comment_82190475

Blimey - that was quick!

Thanks as always, QrizB.

Interesting - so the Sofar will remain in 'charging from the grid' mode for the whole duration the tou is set for this, and won't - cannot - discharge the battery even when it's full and actually stopped charging from the grid long before? Provided the Sofar is timed to charge from the grid, it is effectively 'locked' from discharging during this period?

That's a perfect solution - cheers 🙂

QrizB

Oh, and (if you don't have a comms cable from your ME3000SP to your battery) watch out for the Sofar losing track of the state of charge of your batteries.

Here's a chart from Solarman from a couple of nights ago that shows what I mean.

If you look at the two green traces, the light green SOC rises to an assumed 90% then plateaus. Simultaneously the dark green charging power drops to zero. This is the Sofar thinking it's reached my target SOC.

Then after an hour or so of no charging, the Sofar decides the SOC isn't 90% at all, but is more like 70%, and it resumes charging until 0528 comes around.

This doesn't cause me any huge problems at the moment, but would be awkward if I was hoping to use the full capacity of my battery. This might bite me in December and January when there's no sunshine, and is why I'm working towards getting Sofar-to-battery comms in place.

(Did your Sofar come with a WiFi dongle? Have you installed Solarman?)

WIAWSNB

It has a built in WiFi card, and I've struggled to connect Solarman to it - all sorts of "won't connect" barlocks. About to try splitting my router betwixt 2.4 & 5, and adding a booster to the former to see if that helps.

Yes, mine currently seems to work only on measured battery voltage, but it does some weird stuff at times too!