Solar Panels and Heat Pump fitted but savings not as suggested.

jaynexxx_2

markin said:

A lot of power can be saved by setting the heat pump up 'correctly', Set hot water temp to 43-45c turning off any boost element, Heating water only between 11am and 3pm the warmest part of the day.

The legionnaires cycle to 60c only needs to be every 7 days and is usually separate from the boost element.

Some heatpump models have a terrible 'doing nothing' power draw, So people are turning them off and manually turning on once a day, or every other day for low users just for the hot water over summer.

markin said:

A lot of power can be saved by setting the heat pump up 'correctly', Set hot water temp to 43-45c turning off any boost element, Heating water only between 11am and 3pm the warmest part of the day.

The legionnaires cycle to 60c only needs to be every 7 days and is usually separate from the boost element.

Some heatpump models have a terrible 'doing nothing' power draw, So people are turning them off and manually turning on once a day, or every other day for low users just for the hot water over summer.

Thanks I will look into that. I have changed it to the economic setting but still seems to be Heating the water to 50 degrees 

Reed_Richards

I think you were badly misled.  I have a 12 kW heat pump, 16 solar panels giving a peak power of 4.8 kW (and a battery but you don't have one of those).  Some devices in your home will use more power than your solar panels can provide, even at their peak output.  When my heat pump is heating the hot water the peak power demand is about 6 kW.

In winter I get much less solar power per day and this barely dents the power demand of the heat pump.  My annual electricity input is now about 8200 kWh of which 6900 kWh was used by the heat pump.  8200 kWh is what I import. I don't know what that would be without the solar panels because I can only measure what I generate, not what I export so I don't know how much I use.  The 6900 kWh is the power actually used by the heat pump.  Some of this will be provided by my solar panels but it won't be a large percentage.  



  

jaynexxx_2

Hexane said:

Do others with Solar Panels and heat pumps get mostly free electricity during summer daylight hours?

Ignoring the heat pump (because it's not relevant, it doesn't generate electricity, free or otherwise), yes we get free electricity during daylight hours. This varies between a few hundred watts shortly after dawn - enough to run the house baseload plus a computer and display or LED TV. Up to 6kW on a fiercely sunny day in May or June around noon - enough to run two out of three of a condenser tumble dryer, electric oven on its heating cycle, and a large electric kettle, all simultaneously. Then around 2.5kW at noon on a summer day when it's cloudy but bright, or at 5pm on a sunny June day - enough to run the house baseload plus the heating cycle of either the dishwasher or the washing machine. (Ignore anything you've seen on BBC TV - it's not the spin cycle that consumes most power.) Your generation numbers will be smaller. In the absence of battery storage, doing any of these activities at a time when your solar panels are not generating sufficient to wholly power them, means you will be importing electricity from the grid, which means you pay.

This is where human behaviour comes into it. Most people don't wait until 11am to boil the kettle. Or only boil the kettle when the sun comes out. (But, on this forum at least, some people do.) If you get up at 8am and feel like a cup of tea and your kettle consumes 3kW (not all kettles do...) and you don't have battery storage, you have no way out of paying extra for power imported from the grid. You could prepare your tea with a microwave, but an 800W microwave consumes around 1600W (yes really) so there's still a problem.

From your figures, it sounds like your shower is consuming about 12kW instantaneous power. Which means it's heating the water using (lots of) electricity, and that leads me to wonder, isn't it supposed to be your heat pump that's heating the domestic hot water? We have a power shower, but it's from a tanked system (heated by genuinely free surplus solar power using myenergi eddi) with a pump (providing the "power" part) and running at full power it only consumes 600W.

During the winter it should cover the costs of the heat pump for heating/hot water but not enough to cover the rest of the electricity usage.

This sentence is confusing. There's no way that a system with 12 solar panels (even if they're very high output ones, which I suspect yours aren't) is going to provide enough power in winter to make heat pump usage not require grid import. There's also no way, unless some weird Octopus tariff results in you receiving massive payments per kWh generated, that it will result in payments during the winter sufficient to pay for cost of imported electricity for the heat pump.

What I suspect the sentence might mean, is that over the course of a year, on average, the earnings from exported electricity from the 12 solar panels, is expected to cover the cost of the electricity you'll need to import to run the heat pump. This is optimistic too, but it's at least plausible. Most of the earnings will be generated from April to August.

Which means it comes back to paul991's question, what are you getting paid for your exported electricity? And, how much electricity are you exporting at the moment (when your exports should be relatively higher)?

Thanks for your reply, very helpful. Yes from what I understand, the heat pump heats the hot water in the tank. When we use it, it tops it back up, and presumably its reheats it whenever it cools down. I do need to look into this more to find out exactly how it works. Sometimes we get big 'peaks' in the middle of the night, presumably this is something to so with the heat pump to. 
I am still in the process of setting up the export tariff, I need a letter from the DNO before I can progress any further 

jaynexxx_2

Reed_Richards said:

I think you were badly misled.  I have a 12 kW heat pump, 16 solar panels giving a peak power of 4.8 kW (and a battery but you don't have one of those).  Some devices in your home will use more power than your solar panels can provide, even at their peak output.  When my heat pump is heating the hot water the peak power demand is about 6 kW.

In winter I get much less solar power per day and this barely dents the power demand of the heat pump.  My annual electricity input is now about 8200 kWh of which 6900 kWh was used by the heat pump.  8200 kWh is what I import. I don't know what that would be without the solar panels because I can only measure what I generate, not what I export so I don't know how much I use.  The 6900 kWh is the power actually used by the heat pump.  Some of this will be provided by my solar panels but it won't be a large percentage.  



  

Wow, really! Now I'm really panicking for when we need to turn the heating on, and you have a much bigger system than us. Can I ask how you know how many kwh you used just on the heat pump? 

markin

What Make/ model heat pump is it?

Many will display energy used in the controller menu, and the cop you are getting.

jaynexxx_2

markin said:

What Make/ model heat pump is it?

Many will display energy used in the controller menu, and the cop you are getting.

its a generation 6, 12kw Samsung Heat Pump & Kodiak Smart Cylinder 

Reed_Richards

My heat pump is set to heat the water in the cylinder to 50 C and to reheat when the temperature drops to 45 C or less.  Both the maximum temperature and the temperature drop before a reheat is triggered (5 C in my case) are programmable.  I don't have a Samsung heat pump but I Imagine it's the same.

My heat pump has its own electricity meter so I know exactly how much energy it uses (but not how much of that comes from my solar panels and how much from the grid.  Averaged over the first tow years it was in use (14/12/20 to 13/12/22 it used an average of 5980 kWh per year.

How were you heating your house before you got your heat pump?    

jaynexxx_2

Reed_Richards said:

My heat pump is set to heat the water in the cylinder to 50 C and to reheat when the temperature drops to 45 C or less.  Both the maximum temperature and the temperature drop before a reheat is triggered (5 C in my case) are programmable.  I don't have a Samsung heat pump but I Imagine it's the same.

My heat pump has its own electricity meter so I know exactly how much energy it uses (but not how much of that comes from my solar panels and how much from the grid.  Averaged over the first tow years it was in use (14/12/20 to 13/12/22 it used an average of 5980 kWh per year.

How were you heating your house before you got your heat pump?    

I don't think mine has a separate meter, i have had a look through the display tho, and it does tell me how much energy it has used each day/week or month, which is helpful. It was set at 50 C but i have dropped it down to 45 C.  Not sure what the reheat temperature is tho, i will keep checking it.  I presume its ok to have it set at 45 C? 

We were previously on LPG for hot water/heating.  

Reed_Richards

If your heat pump system was properly installed I think it should be cheaper to run than your LPG boiler was.

If setting the temperature to 45 C gives you enough hot water then that is absolutely fine.  


       

chris_n

Using electric showers when you have a heat pump or gas and storage is madness. It is just like burning £10 notes. The claims that the solar would cover most of your daytime usage is true for most people using electricity in the way that it is expected to be used. I own a property in the UK and it only imports during the day on occasional days when the weather is reallybad (today).
Even if your panels were at full tilt you would still be importing 7kW. Maybe misunderstood rather than. misled or misheard would be the order of the day.