Consuming excess solar with smart plugs?

Heedtheadvice

I you export the max you can under SEG (and get paid for it) but still have an excess then you have already discounted the two options of choice ( battery and diverter). What would those have cost you?( just to put into perspective what you might budget for any alternative).

Would any solution be DIY or commercially installed? I.e. have you the competence to do basic work or would you need to buy that in in terms of hardware installation, software to control, design and calculation ability etc. or need an off the shelf solution..

QrizB

When replying to this thread, plase note that it dates from 2023 and the OP @SolarSoGood hasn't been around since then.

It's been bumped by @FFHillbilly who has a related problem (10kWp of panel, 7.5kW inverter, 5kW export limit - so presumably export is sensed by the inverter and limited in software) and wants to automate load switching to make use of the 2.5kW of headroom between his inverter capacity and export limit.

The more recent poster seems to e looking for a Smart Home / IoT option. There are lots of ways to do this but one option would be a Shelly EM to measure what's being exported, some Shelly1 smart switches for the loads, and then set up the automation in the Shelly app.

(Note that I'm not actually doing this myself and have no first-hand experience, but from all accounts it should be relatively straightforward. I have a much more Heath Robinson setup.)

Heedtheadvice

.........envisages the heating effect of current in cable, expanding a wire attached to a wheel rotating a switch to start a heater to boil a jug of water for a cuppa using up the wasted excess power with something satisfying .....

Much missing to get to the Heath Robinson standard!!

FFHillbilly

I've got 2 plans to use the excess solar, which is getting more and more every day it seems

1. I'm getting an EV work van, test driven a Kia PV5 van and its great just waiting for the 3 seater version which should be out within a year. that should take a chunk of the excess power but realistically only at weekends when it will be parked all day and I'll plug it in to charge.
2. Unvented hot water cylinder in the loft right above my bathroom which will serve the main shower, bathroom basin, and utility sink hot water needs. If I get an Eddi diverter I can just use the solar to heat the hot water between March-October, and it will be connected to the combi boiler for winter top ups using gas. Kitchen sink hot water is currently served by the boiling water tap which i think is "free", and if I need a sink full I do use the combi and ill leave it like that as it would be a bit of a job to get pipes down there

QrizB

Are there any systems that achieve this please?

I know the OP has a Solis inverter so this won't be any immediate help, but (having bought one myself) I know the Ecoflow inverters and batteries, used with the Ecoflow app, will let you set up rules using smart plugs and other devices from Ecoflow, Shelly and other manufacturers.

Unfortunately there doesn't seem to be a generic ZigBee integration (or if there is, I've not found it yet).

I'm getting an EV work van ...

If you get an EV work van, you might want to consider an EV tariff. On some of these off-peak electricity is priced lower than the SEG tariffs that you're paid for export, so it's more cost-effective to export your spare daytime generation rather than try to divert it into an EV.

Unvented hot water cylinder ...

Again, it's likely to cost less if you heat the tank on cheap EV-rate electricity and export your surplus. This will also save you the cost of a solar diverter.

For example, I'm on fixed Intelligent Octopus Go for import, and Outgoing for export. I can charge my EV and heat my HW tank at 8p/kWh overnight while selling solar surplus for 12p/kWh in the daytime. It makes no sense whatsoever for me to divert daytime solar to the EV or HW tank.

FFHillbilly

I get what you mean but I have reached my export limit, I'm not planning on reducing my exporting in the day to charge the Van or heat the water, it will just be using the 2.5kw that isn't currently generated because theres no demand for it

I would say I'm losing around 18-20kWh each day as I just have no demand for it, when the battery is charged at 9-10am the inverter just produces 5.3kw, 300w to run the house and 5kw to export. it's rated at 7.5kW, I know it can actually go slightly above that as on some days I do laundry mid day if I come home for lunch and the inverter then increases it's power to 7.8kw for the brief time the machines are on

I will need to get an EV tariff to charge Nov-Feb, and will likely use the gas to heat the hot water cylinder during this period too but I plan on using the excess solar for the rest of the year.

the EV tariff will also mean that I can charge the battery overnight in winter and therefore only spend 9p /kWh for 95% of the winter, another bonus

QrizB

when the battery is charged at 9-10am

I don't think you've said how big your battery is? Apologies if you've shared this information and I've missed it.

Can you change the priorities so your system only charges the battery after it's hit its export limit?

And can you set your battery to discharge to the grid after dark so it's empty by sunrise?

FFHillbilly

it's 9kWhr. and I rarely dipped below 60% in the mornings so I have actually set it to max charge to 80% in the summer, will probably change that in winter

I'm not sure I can change the settings so that it charges in the daytime, however it would realistically only deal with 3kWhr max

I did think about force discharging, but I want the battery to run the house for free so I wouldn't want to discharge it all. the time I would think about doing it would be 9AM, but it would depend on if it's going to be sunny or not that day? It also puts a lot more charge cycles on the battery for not a great deal of return in my opinion so am not really keen on that idea

QrizB

It's entirely your call but I'd definitely consider force discharging your battery at this time of year, and then setting your inverter to only charge the battery after hitting the export limit.

It also puts a lot more charge cycles on the battery for not a great deal of return in my opinion

The question then is, why do you have the battery? Most recent batteries are rated for at least 4000 cycles, which is 11 years at one cycle a day. If you're not going to cycle it daily, you're not going to see the financial benefits of having it.