Best Solar Panels for Winter

[carptench]

Hi All

Looking to install a 12kw solar array but not sure whether its too much or not enough. We use around 10k kwh annually and obviously a higher percentage of this would be used between October to March. Looking at our historic meter readings we use around 60% of the 10k in the winter months.
I realise that it would be very difficult and expensive not to use any grid power but want to try and get it right to start with to maximise energy throughout the year.

We will be installing energy dumps to the heating system and are considering batteries. The batteries I'm struggling with without having a good idea of winter production from the panels.
So I suppose my question is what would a 12kw solar array produce during the winter months (October to March). What panels would out perform others during winter use?

Thanks
M

 

[binky]

simple fact is there's less sunshine in winter and the hours of sunshine or shorter, so performance always drops. If you are lucky enough to have space for a ground array, you can mitigate winter output by using a steeper panel pitch ie have them more upright. You will lose output over summer if you do this, but it may suite your needs better?

As for panels, size of array makes a difference, but the more efficient the panel the better it will work in winter, and any other time of year for that matter. Good, reasonably priced panels are around 20% efficient.

Batteries, also won't do much for you in winter, but for the rest of the year will work well.

The only real way of getting decent winter green energy is a wind turbine, if you have a suitable location for one where it won't pee-off the neighbours.

 

[carptench]

simple fact is there's less sunshine in winter and the hours of sunshine or shorter, so performance always drops. If you are lucky enough to have space for a ground array, you can mitigate winter output by using a steeper panel pitch ie have them more upright. You will lose output over summer if you do this, but it may suite your needs better?

As for panels, size of array makes a difference, but the more efficient the panel the better it will work in winter, and any other time of year for that matter. Good, reasonably priced panels are around 20% efficient.

Batteries, also won't do much for you in winter, but for the rest of the year will work well.

The only real way of getting decent winter green energy is a wind turbine, if you have a suitable location for one where it won't pee-off the neighbours.

Thanks Binky
We are going to be ground mounting them so what you are saying does make sense.
So what would be expected over the winter period.5% 10%, 20% of capacity. Really blind at the minute and cant begin to size a system without knowing realistic figures.
Was looking at the Q cell G9 panels which are 20.3 efficient. What do you think of those?

 

[binky]

winter outputs can be rather variable, this year has been crap in the SW due to constant cloud cover. Have a look at the SMA portal, they have a lot of 'public' systems on there, so you can see real world figures from your area/ similar size systems rather than guesstimates from the likes of myself.

 

[carptench]

That's great Binky thank you will have a look.

 

[carptench]

winter outputs can be rather variable, this year has been crap in the SW due to constant cloud cover. Have a look at the SMA portal, they have a lot of 'public' systems on there, so you can see real world figures from your area/ similar size systems rather than guesstimates from the likes of myself.

Thanks for the link Binky. Its a great website. A lot of the information on there is limited to annual production but some users do have the daily charts attached which has been helpful.
It looks like the production figures over the winter months drops rapidly so battery storage isn't going to work without a huge solar array, which would be wasted for 7 months of the year.
I think realistically for me its going to be a case of scaling back on the PV array say to about 6kw and installing a immersion heater dump, which should cover most of our use during the warmer months. Maybe just add a small battery bank to complement this. Then look at something else for the winter period. I know you mentioned a wind turbine and this is something we did look at a few years ago, but we are on the border of it not being viable due to the wind speeds in our area. It a huge outlay for it not to work!
We run a air source heat pump for our heating and would like to say its 300% efficient as sold to us but its not. It sucks around 3kw constantly when the temperature drops below 10 degrees outside. Maybe we should look at something else as a heating source maybe Biomass?

 

[Berserkerboy]

Winter is bad news for solar here with us. Prior to solar we used around 10kwh of lecky per day. However, with just 3.6kw of solar and an immersion diverter we are averaging 6.6kwh Jan, 6.0kwh Feb, 4.8kwh Mar, 3.9kwh April of grid power per day. I often see that we are exporting power once the water is as hot as it can be.
With battery backup of say 5kwh I believe we would be near zero grid power April-Sept and have free hot water for most of this time. It would also greatly reduce the diligence needed to try and self consume as much as possible. Unfortunately, the DNO is currently not agreeing to an AC coupled inverter as we use microinverters.
I should add that our panels face in 3 different directions to smooth production thoughout the day and we have invested in more energy efficient appliances.

Interesting the comment about the ASHP sucking 3kw constantly. Disappointing!! Glad we didn't go ahead with ours. They insisted we would have to remove our wood burning Rayburn which provides hot water, central heating and cooking, in order to benefit from the grant. Never gonna happen as we have our own wood and are planting more trees on spare land.

 

[carptench]

Winter is bad news for solar here with us. Prior to solar we used around 10kwh of lecky per day. However, with just 3.6kw of solar and an immersion diverter we are averaging 6.6kwh Jan, 6.0kwh Feb, 4.8kwh Mar, 3.9kwh April of grid power per day. I often see that we are exporting power once the water is as hot as it can be.
With battery backup of say 5kwh I believe we would be near zero grid power April-Sept and have free hot water for most of this time. It would also greatly reduce the diligence needed to try and self consume as much as possible. Unfortunately, the DNO is currently not agreeing to an AC coupled inverter as we use microinverters.
I should add that our panels face in 3 different directions to smooth production thoughout the day and we have invested in more energy efficient appliances.

Interesting the comment about the ASHP sucking 3kw constantly. Disappointing!! Glad we didn't go ahead with ours. They insisted we would have to remove our wood burning Rayburn which provides hot water, central heating and cooking, in order to benefit from the grant. Never gonna happen as we have our own wood and are planting more trees on spare land.

Yeah the air source heat pump is not good in the winter. We have underfloor heating throughout the whole house and its also well insulated as only 8 years old. I try and get away with setting the room stats to 19/20c but not really warm enough (According to the wife). Even then we can easily use 50kwh a day between Nov and Feb. Before lowering the room stats we would use much more. Our exact usage over the last 4 years has been 46k kwh. To be fair the heat pump didn't cost us anything as we got 7k RHI payment which more than covered the cost of installing it.
Think you made the right call keeping the Rayburn and I think we are going to look to doing a similar setup with either a pellet stove or multifuel burner with back boiler to assist the heat pump. Not sure how doable it is yet as the ASHP is on a unvented system which doesn't work with back boilers.
What is your solar set up and immersion heater diverter?

 

[Berserkerboy]

3.6kw panels with Enphase micro-inverters. Panels are in 3 arrays facing different directions to smooth out generation. Solic 200 immersion diverter. It has a 10 years back to base warranty if installed by an electrician. Our friendly electrician put it in whilst upgrading our Consumer Unit, so that cost nothing and he just signed the warranty form that had to be sent off. The diverter goes between the CU and the immersion heater with a CT sensor around the grid input cable. Couldn't be simpler.. Very happy with it.

 

[carptench]

3.6kw panels with Enphase micro-inverters. Panels are in 3 arrays facing different directions to smooth out generation. Solic 200 immersion diverter. It has a 10 years back to base warranty if installed by an electrician. Our friendly electrician put it in whilst upgrading our Consumer Unit, so that cost nothing and he just signed the warranty form that had to be sent off. The diverter goes between the CU and the immersion heater with a CT sensor around the grid input cable. Couldn't be simpler.. Very happy with it.

Nice one thanks for the info.
Does using micro inverters improve the system if there isn't a shade issue or panels facing different directions? Are you using a Solic Inverter?

 

[Berserkerboy]

Micro-inverters are a must for us, as some panels face East, some South East, and some South West. I wanted to smooth production over the day as there is no FIT. Also, at least some of the panels are more likely to see some sun straight on. ie a cloudy morning but sunny afternoon would get some decent generation and vice versa. Sunny day and we're quids in,.., but it's Wales!.
I'm very pleased with our setup results.
If you have panels facing the same way without shading, micro-inverters are not so necessary. However, they just daisy chain together and so are easy to install. They are also solid state and in theory much more reliable than string inverters.

I only need a Solis inverter if Western Power will let me have batteries. It would provide the conversion from DC to AC from the batteries. Western Power have an issue, as in theory we could export more than 3.6kw back to the grid. Still waiting on whether they would approve if we set the G100 compliant Solis to zero export.

Back to your original post and how much power you'll get in the winter. Looking at our historical production, as Binky said, winter is very poor. Nov through to end of January we didn't get over 4kwh on any day. Middle of December we averaged 1.2kwh per day.
We have 3.6kw capacity so you get the picture.
Many people have an unrealistic idea of how much they'll get in Winter. We are happy that for 9 months of the year we're producing the bulk of our needs.

 

[binky]

Micro-inverters are a must for us, as some panels face East, some South East, and some South West. I wanted to smooth production over the day as there is no FIT. Also, at least some of the panels are more likely to see some sun straight on. ie a cloudy morning but sunny afternoon would get some decent generation and vice versa. Sunny day and we're quids in,.., but it's Wales!.
I'm very pleased with our setup results.
If you have panels facing the same way without shading, micro-inverters are not so necessary. However, they just daisy chain together and so are easy to install. They are also solid state and in theory much more reliable than string inverters.

I only need a Solic inverter if Western Power will let me have batteries. It would provide the conversion from DC to AC from the batteries. Western Power have an issue, as in theory we could export more than 3.6kw back to the grid. Still waiting on whether they would approve if we set the G100 compliant Solic to zero export.

Back to your original post and how much power you'll get in the winter. Looking at our historical production, as Binky said, winter is very poor. Nov through to end of January we didn't get over 4kwh on any day. Middle of December we averaged 1.2kwh per day.
We have 3.6kw capacity so you get the picture.
Many people have an unrealistic idea of how much they'll get in Winter. We are happy that for 9 months of the year we're producing the bulk of our needs.

Solic is an immersion controller. This winter has been bad, previous winters have been much better, but warm damp gloomy winters seem to becoming the norm.

Microinverters can offer a slight performance gain on unshaded roofs, but the gain generally doesn't merit the extra cost.

 

[carptench]

Ok great thanks. I was getting confused with Optimisers and Micro Inverters. Obviously you wouldn't need an Inverter if using Enphase.
The figures you've sent are pretty much inline with a lot of the systems on the SMA Portal. Probably around 10 to 15% of the rated capacity for those periods.
Large battery banks would never get charged over the winter like Binky has already pointed out.
With regards to the Solic immersion controller. We have a 3kw immersion heater on our hot water tank. If for instance we were producing 4kw from the panels and using 2kw within the property, could we use the spare 2kw to power the immersion heater without topping up the supply power from the grid to the immersion heater? So in effect the immersion heater would have 2kw going to it not 3kw as rated.

 

[Berserkerboy]

Ha ha. Yes of course, Solic is my immersion diverter. I was getting Solic and Solis confused. Senior moment. Sorry. Post amended.
Carptench. I imagine you are already familiar with them, but Plug in Solar provided all our settup. At the time they were really excellent with advice and competitive too.

 

[Berserkerboy]

Ok great thanks. I was getting confused with Optimisers and Micro Inverters. Obviously you wouldn't need an Inverter if using Enphase.
The figures you've sent are pretty much inline with a lot of the systems on the SMA Portal. Probably around 10 to 15% of the rated capacity for those periods.
Large battery banks would never get charged over the winter like Binky has already pointed out.
With regards to the Solic immersion controller. We have a 3kw immersion heater on our hot water tank. If for instance we were producing 4kw from the panels and using 2kw within the property, could we use the spare 2kw to power the immersion heater without topping up the supply power from the grid to the immersion heater? So in effect the immersion heater would have 2kw going to it not 3kw as rated.

That's exactly how they work. They only offer the excess generation that is being exported otherwise. So they can offer the immersion from 1w to 3000w.

 

[carptench]

Cool. Definitely the way to go then

 

[Berserkerboy]

Our settup with the CU. Just enough room for everything.

 

[carptench]

Looks good. The immersion controller is a must I think. We spend £600 a year just heating the hot water so should pay for itself over the first summer.

 

[user 34936]

Micro-inverters are a must for us, as some panels face East, some South East, and some South West. I wanted to smooth production over the day as there is no FIT. Also, at least some of the panels are more likely to see some sun straight on. ie a cloudy morning but sunny afternoon would get some decent generation and vice versa. Sunny day and we're quids in,.., but it's Wales!.
I'm very pleased with our setup results.
If you have panels facing the same way without shading, micro-inverters are not so necessary. However, they just daisy chain together and so are easy to install. They are also solid state and in theory much more reliable than string inverters.

I only need a Solis inverter if Western Power will let me have batteries. It would provide the conversion from DC to AC from the batteries. Western Power have an issue, as in theory we could export more than 3.6kw back to the grid. Still waiting on whether they would approve if we set the G100 compliant Solis to zero export.

Back to your original post and how much power you'll get in the winter. Looking at our historical production, as Binky said, winter is very poor. Nov through to end of January we didn't get over 4kwh on any day. Middle of December we averaged 1.2kwh per day.
We have 3.6kw capacity so you get the picture.
Many people have an unrealistic idea of how much they'll get in Winter. We are happy that for 9 months of the year we're producing the bulk of our needs.

Which Solis did G100 compliment please?

 

[Berserkerboy]

Which Solis did G100 compliment please?

Not sure what you mean?