Solar panels and battery - any real world reccomendations?

casper_uk said:
Is that not true then? It makes sense to me that it is correct, and there would be enough juice left for 30 minutes more of use of the kettle. :confused: maybe the terminology is slightly wrong, but the gist of the calculations are right?
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No, read above, a kw is a measure of current power usage, a kwh is the same but over time, for an hour.

If you use a kettle that draws 2kw for 2 hours, you will have used 4 kwh, not 4 kw.
 
Your supplier bills you per unit which is 1 kwh. The meter installed is there to measure this. As above the appliances that draw power/load tell you how much they use. A 2kw kettle left on for one hour should use approx 2 kwh or 2 units on your electric meter.
 
HungryHippos said:
No, read above, a kw is a measure of current power usage, a kwh is the same but over time, for an hour.

If you use a kettle that draws 2kw for 2 hours, you will have used 4 kwh, not 4 kw.
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So the math is correct, but the terminology is wrong, got it. You will have used 4 units (pointed out by gpuerrilla) as billed by your energy provider. 4 units, 4kw, 4kwh, it will all cost the same amount.
 
casper_uk said:
So the math is correct, but the terminology is wrong, got it. You will have used 4 units (pointed out by gpuerrilla) as billed by your energy provider. 4 units, 4kw, 4kwh, it will all cost the same amount.
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Yes sort of, it would be incorrect to call it 4kw used though, because a kw is something else. A unit as mentioned is a kwh on your bill.

4 units == 4 kwh != 4kw
 
casper_uk said:
So the math is correct, but the terminology is wrong, got it. You will have used 4 units (pointed out by gpuerrilla) as billed by your energy provider. 4 units, 4kw, 4kwh, it will all cost the same amount.
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HungryHippos said:
Yes sort of, it would be incorrect to call it 4kw used though, because a kw is something else. A unit as mentioned is a kwh on your bill.

4 units == 4 kwh != 4kw
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Cool. So basically I was just using the terminology wrong and should have used kWh instead of kW, as everything else is exactly the same. Good to know I understood how it works fine in the end :)
 
To confuse you even further, some appliances usually dishwashers and washing machines give their draw "per cycle".

So if you dishwasher states 1kwh per cycle, that's how much it uses it total from start to finish, but the time period can vary, eg a "cycle" could be three hours, or an hour and a half, it still uses the same stated amount.

Also the draw isn't constant over the cycle, when it's just the pump going in a dishwasher for example it's probably using hardly anything, but the heat cycles will have high draw for shorter period etc
 
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Bear in mind all these appliances and gadgets are on/off during the day so your total load fluctuates. Watts matter but so does knowing what devices are on and what needs to be on.

Since solar installed I now use both dishwasher and washing machine on the Eco mode as it uses the least power and it may take three times longer to be that efficient. You then have a better chance of staying within your panels capacity thus draw less bursts from the grid.
 
Over the summer I've actually been doing the opposite since solar was installed and using the full 70c dishwasher cycle. Definitely washes stuff better. Will have to go back to eco cycle soon I expect.
 
Yea I think it depends on the sun.

If it's a clear day and you know are going to have a constant few hours sun at say 3+ kw I'll put it on intensive.

If it's more hazy or sunny spells I'll use eco.
 
SoliD said:
Over the summer I've actually been doing the opposite since solar was installed and using the full 70c dishwasher cycle. Definitely washes stuff better. Will have to go back to eco cycle soon I expect.
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I dont have a battery so that may explain my behaviour. Or you have batteries that cover this. What can the batteries provide before its too much and needs grid power?
 
gpuerrilla said:
I dont have a battery so that may explain my behaviour. Or you have batteries that cover this. What can the batteries provide before its too much and needs grid power?
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batteries here so 2.6kwh before drawing from the grid, so up until yesterday anything around lunch was sufficient to cope with the short periods it consumes 3kwh for the heat cycles
 
Yep it seems that 2.6kw + current generation - current usage is used before it goes to grid.

So if battery charged, and currently generating 2kw on solar, it can cover short bursts on a kettle or washing cycle without the grid.

If it's nighttime though, then after that 2.6kw it's always going to be getting something from the grid.

Grid day usage seems fairly minimal though, so far I've had less than 1 kwh per day from the grid outside of the Go hours.
 
My observations of appliances so far have been, using dishwasher on terrible setting can spike to 2kw, washing machine not so bad but you shouldnt need to wash at high temps these days, but the fridge/freezer and we also have a small seperate solo freezer means the base draw of the house can sometimes be 100w without others. If you have people in the house that flip on the kettle and say hairdryer - your potentially scuppering your solar provision as the spikes disrupt, then taking from the grid.
 
My base usage is nearer 200w. All the main standby devices get shut down, but 5 ring cameras, 7 mesh access points, 6 echo's etc all bleed power.
 
Does anyone know if you have a say 5kw hybrid inverter. Panels that can generate say 5kw and a battery that can discharge 4kw, is your peak output to your house 5kw (based on inverter), or 9kw based on solar of 5k (assuming its mid day bright sun etc) plus the 4k from the battery.

I haven't seen it listed anywhere as a max or anything and wondered if this why the inverters seem to be listed as eg 5kw and yet the specs inside often have differing numbers per source.

The highest peak kw I have seen so far on my IHD was 5.8kw the other night. Some lights, pc etc were on. I went down, flicked on the kettle to boil some water for a coffee, and turned on the oven, walked to the freezer where the IHD is and saw that 5.8 at that time.
So a few minutes later it would have dropped to more like 2.8, but got me curious as to if that would have exceeded the ability for the inverter (had it been sunny at the time) or if the inverter would in effect be able to go above 5 so upto the 5.8 demand at the time.

Hope that makes sense :)
 
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