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Which solar for me?

  • 23-02-2023 12:06am
    Registered Users Posts: 108 ✭✭

    Looking for advice please, interested in solar pv,but unsure what is suitable ,my current daily use is based on day/ night meter ,my current use is daily between 5 and 7 kw, usually between hours of 5pm till 11 pm,and night is 4 kw up to 11 kw depending as have phev which is 8.9kwh battery and charge approx 4 times a week, other night use is washing machine,tumble dryer,dish washer , couple times weekly,based on that i presume i would need battery with pv what kWh would you suggest and battery size,was thinking around 4kwh but unsure, want to have as much information before i ask for quotes,i was hoping to get just panels as can't really afford battery as seem very expensive but am i right in saying if iam not there during daytime,i need to store power to use at night time.


  • Registered Users Posts: 2,730 ✭✭✭yankinlk

    What space and aspect is available for panels? South facing? East west? Roughly how much room for panels? You could have a small system generate 10 kwh easily, but if you are only at home after 5 it will all go to grid. Buying a big battery to store it will be expensive.

    You could cover that day rate with a small system and get paid a little for the export thru FIT payment and no battery.

    Your load shifting habit is a great start already and knowing your usage helps.

  • Registered Users Posts: 108 ✭✭baz69

    Thanks for reply, south facing detached house but an extension was put on so panels not sure would think possibly 6 or 8 maybe,that's my problem not there during the day much,so would have to get a battery but what size?.

  • Registered Users Posts: 108 ✭✭baz69

    Also what i meant to say was,a rep calling around next week,so wanted to have as much information especially on with my usage,what kWh panels would i need and size battery , reading more i realize i need a battery for my needs to maximize usage.

  • Registered Users Posts: 1,401 ✭✭✭DC999

    Don’t need a battery. It’s optimal, but ways around it. I don’t have one – funds won’t allow. You're gonna export a lot as not home during day - which is fine and get @20C per unit for export. Tax liable above €200 self declared on Revenue site (same as for any revenue).

    • Is phev at home during the day at all even a few days a week? If so can get a Zappi charger to charge from sun (when house is empty). Costs ~1.5k supply and fit. Or ignore it and stay on existing charger and use cheap night rate. Then you have a 8.9kWh battery!! It can't feed back into the house though.
    • Run stuff during the day while you're at work. Get €10 smart plugs to run your washing machine, dishwasher… Run 1 device at a time. All you do is set a recurring start time on the smart plug. 11am daily for washing machine. Same for dishwasher when washing machine ends. Before you leave the house, or night before, turn the machine one. Then turn the smart plug off (via Alexa or app on your phone). Job done!
    • Or set the timer on the device. Can do that the night before again (depending on how long the timer allows). My new washing machine uses a few watts a day on standby. Watch out for older machines on standby though, can be heavier on juice. Don’t want them sucking juice on standby for no reason. Can set tumble dryer to run on 'delicate' - 1.4kW on mine, down from 3.5kW normally. Tbh I don't use ours, but can set many devices to 'eco' (dishwasher, washing machine) to use less juice and max solar
    • Add a West roof to give sun in the evening. Will produce less than south but extends the day. See can you get some West too as well as the South. Check it's not more North (N) than W. My NW panels go to sleep for 5 months from late Sept (but still worthwhile rest of the year to extend the day). East will give sun in the morning but won't really have ramped up by the time you're leaving if before 9am. So less use to you.

  • Registered Users Posts: 108 ✭✭baz69

    Wow lots of info there, thanks,so actually iam at home each day retired,so using machines during daytime or charging car is not a problem, although technically iam home spend most of day out walking dogs , cycling etc so no real power used in house until 5pm till 11pm then usually use machines twice weekly,and plug car in have wallbox running at 32amps,so if i used machines say during daytime and charge car at night rate that just leave me with the usage in evening between 5and 7kwh,?

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  • Registered Users Posts: 1,401 ✭✭✭DC999

    You've a D/N and do load shift. Can you reduce some of the 7kWh used each evening? That can't benefit from (much) solar or the night rate.

    Is that electric heating? Immersion? Showers? Or cooking - which can't move of course? Could do the likes of a a slow cooker dinner once a week as you're at home during the day, or stuff along the lines to do a 'low and slow' use of energy (from solar) to get the same result.

    Heating uses the most juice (heating the house, heating food (to eat), heating water - showers, kettles)

  • Registered Users Posts: 108 ✭✭baz69

    Thanks,Evening would be heating from 5till9 set at 19 degrees aluminum rads, Viessmann gas condensing boiler with indirect tank,water takes priority for 15 min ,showers are pump fed, induction hob and A rated oven,btw gas usage at moment varies after conversion ,22to 33kwh, unfortunately most of the usage is only after 5pm,which equates to 5kwh the other days wherzit might be 7kwh is if i don't go out,tv on kettle used.

  • Registered Users Posts: 25 mingkim

    Does anyone know if increasing the size of an immersion tank (it's due to be replaced )and solar going in around may...if I increase to a 300 litre tank will it take ages to heat up and will it take all my solar energy that I'm going to need for the house during the day.we are high users of electricity and have a 9kw system with a 5 kw battery and Eddie going in soon ...but I don't know if I should keep the immersion tank the same 160 litre size or get the larger tank.if some solar energy is heating it every day will it eventually keep it hot?


  • Registered Users Posts: 2,730 ✭✭✭yankinlk

    Thats complicated.

    What time of day do u need hot water? Too early and solar wont heat it anyway.

    What other ways can you heat it? Oil or gas or electric only? Whats cheapest?

    How long are the showers? Short? Maybe electric shower is better if you want it on demand.

    What meter do you have? Are you on a day night meter and getting paid deemed export? Then u can put all excess into the tank and still get paid same FIT.

    If you are on a smart meter... Then FIT might be worth more than trying to heat a tank of water all day long....

  • Registered Users Posts: 1,401 ✭✭✭DC999

    Sounds like you need a new tank for whatever reason. If so, get a larger one instead of staying with same size. New ones are much better insulated so hold the heat longer. And don't even need solar to heat it. Can heat ftom the immersion on cheap night rate if / when you have it.

    I was gonna get our tank replaced when we got solar but cancelled it. We don't use the hot water tank. Have an electric shower and we were going to replace with a pumped one fed from tank. But any plumber can do that for us down the line. Don't need our solar crowd to do it. Will do it at some stage before kids become teens with extra long showers. But we can wait

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