I've got a Solar iBoost to that I'd like to give solar preference over the battery to heat the hot water in the mornings up until 9am. Currently the battery always gets preference. Can I set a timer to allow this to happen?
Thanks
Evantis I am not sure about iBoost, it may be possible but you can set timers on the battery to not charge, however some have had issues on this forum with that, its not completely obvious what each setting does from the names in the remote control page. Do you want the battery to discharge into the iBoost or simply neither charge or discharge in that time period. It may require a little experimentation to get the function you want. Sorry I can't help more but I am relatively new user myself.
Evantis
Set a Timed Discharge in the Settings tab on the inverter from, say 7:30 am to 09:00am. This will then push the solar generation into the home, which the iBoost will use once it senses export above the level set in the iBoost settings.
Of course, if it is cloudy and there's no generation, the battery will discharge.
Also, if the water is hot then the PV generation will be exported during this period if it is in excess of the house load.
I have been thinking about the maths of my Solar iBoost+.
When my system was installed 4 years ago I only had 13 panels and export was very low rate (5p/kWh), so it sort of made sense. Now I have 27 panels and a battery and export 15p/kWh.
I am on Eco7.
Night import 15.27p/kWh
Day import 33.06p/kWh
Anytime export 15p/kWh
Gas 6.83p/kWh
So it is cheaper for me to use any solar in the day into the house electric even if I am still running on battery from night before, or sell it and let the gas boiler do the heating.
I have turned the iBoost+ off.
Am I missing something here?
SteveCook You're not missing anything really - except you're burning gas and emitting some nasty stuff from the flue in one case, and in the other case you're not 🙂
You may as well leave it in place - when the boiler fails & can't be repaired quickly then the iBoost is programmable so the battery/mains will heat the water sensibly.
SteveCook Should probably consider the efficiency of the gas... electric is, to a good approximation, 100% efficient. For gas, the combustion itself is inefficient, and there will be losses from circulating the water. (My CH pump is surprisingly power-hungry, but modern pumps are probably a lot better.) Then there are losses due to residual heat left in the boiler and pipework. If it's a condensing boiler, the return temperature may not be low enough to allow condensation.
During winter, if gas CH is on anyway, the inefficiencies are probably lower. In summer, firing up the boiler for just the HW, they may be higher.
All that said, probably not so bad that the gas is actually more expensive than your night-time electricity.
(FWIW, I'm choosing to use electricity at 9p overnight, vs gas at roughly 6p - Octopus tracker varies day to day.)
DD Probably not a lot in it in terms of efficiency with inverter losses included for heat or export from battery/PV.
Same calculation for me on oil. Much cheaper to heat with the oil and export those extra kWh on Flux.
As others have said, there’s the environmental impact though which I consider important. I use the iboost in summer and spring, it’s off right now.
Made up an ESP module to talk to the iboost+ via Home Assistant and display the data. That was all working, but now iboost has died. I have checked immersion heater and internal fuse, but it just pops the MCB even when the immersion heater is disconnected. Worked fine for 5 years and it looks like an internal problem. Marlec have said "5 years old, we cannot repair, buy a new one". When I add another £350 into the economics it is better for me to use gas and sell my excess power. I put in the iboost to to my bit for the planet, but I am not shelling out £350 every couple of years. Others seem to have reported similar issues
Could switch to the Tesla T-Stat - it plays nice in home assistant and it just bolts on to the head of the immersion.
hoggy
Thanks. Looks good, but when the thermal store was installed (previous owner) an insulated copper pipe passes right in front of the immersion heater and i may not have room for the head. Also my man maths says I am probably better off exporting and using gas to heat the hot water- not green I know
SteveCook Depending on your tariff you could just use a time-switch on the immersion heater. My gas tariff is around 6p and I reckon I lose 50% on the pipework - particularly in the summer. The boiler's in the loft so there's a fair amount of primary pipe water to heat up when re-heating the HW tank (a Megaflo). If the import tariff is below 12p I heat the water with the immersion heater at the same time as charging the batteries and don't allow the boiler to run. Then as much solar as possible gets exported next day at 16.5p. Otherwise I heat the water with gas.
These are the days it was worth doing....
Note that was a good period in May-June. July has been a lot higher priced on the Agile tariff but if your import tariff includes periods below 12p it would still be worth doing.
Thanks
My gas is 6.3p and I have a condensing system boiler about 1m from the thermal store. The internal boiler pump does the circulation to the store.
My day export rate on flux is 9.6p and peak 27.1p
SteveCook condensing system boiler
Not my area of expertise, but is the flow temperature low enough to allow condensing when heating water?
The boiler and tank thermostat is set about 50C and that is plenty hot enough for our taps and bath etc. Now and again I do a pastuerisation cycle and turn it up to 65 for a day.
The thermal store also does the underfloor heating and 50c is fine for the manifolds which then blend it down a bit lower
SteveCook Your system has a higher efficiency than mine so even at 9.6p it is probably worth exporting all you can and use the gas for water heating. Does your import tariff ever drop below 9.6p (Octopus Go for example) or are you limited to Flux 16.4p?
We run our hot water at 60oC needing a flow of 70oC and with pipes to Rads the boiler often isn't condensing. Something I will try to improve overwinter.
Bought a bridge rectifier (£6) from RS and soldered it into the iBoost+. All working now.
SteveCook Oh well done.
I assume the bridge rectifier is for the iBoost controller supply not to feed DC into the heating element? What made it pop do you think?
I had to do a similar repair on our Church pipe organ. The breaker wouldn't stay on and there was a smell of burning. The organ uses 24v for all the solenoids and the bridge rectifier had died. I found that a combination of stops put a dead short across the 24v. I couldn't trace the fault (far too complex wiring) so added several car headlamp bulbs in series/parallel in the 24v positive supply. Now when the fault occurs we know straight away as the bulbs light up. Otherwise they glow very dimly. Much better than blowing a fuse or dropping a breaker.
Sorry I dont know what the bridge rectifier was/is for.
I followed some youtube guidance on replacing the rectifier inside the iboost+ assembly.
It seems a lot of them fail and Marlec are not interested after a couple of years.
My iboost+ is on a dedicated breaker, so no big deal if it goes off.