Solar Energy

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Can putting Solar panels on your house save you money?
Quick answer is YES.

Can they pay back what they cost in a reasonable time?
Well, this isn't as straight forward. This depends on how much energy you use and how much cost per unit it is. Having a 4kw system on the house it took around 7 years to pay for itself, and energy costs was around 16p per kwH. Things have changed since having the panels installed. Cost of electric is over double what it was. Also any new systems you dont get paid for selling back to the grid(I'll cover this later)

How much can it save?
The 4kw system on the house generated around 3600kWh over the year. Say if our energy costs is 48p per unit, that 'could' save you £1728 per year. The reason I say 'could' is if you dont use the energy you generate, it is lost. The summer months it can generate over 20kWh in a day, but if you only use 4kWh in a day, then the 16kWh left over is lost(unless you store it). So really you are only saving electric when you are using electric when the sun is out. Ideal to cook the roast dinner while the sun at mud day, as it would be totally free. Often seeing 3kw being generated. So boiling a kettle would be free at that time.

Before solar panels I was using 2200kWh from the grid. After installing panels I was buying in 1200kWh. The house is using power overnight, fridge, things on stand by etc, boiling the kettle when the sun wasn't out. Having a shower is 10kWh for however long you take. So there is plenty of energy being used that solar isn't helping with.

Costs
The cost of panels are fairly cheap, around £150 for a 400w panel which is 1mx2m. 10 of these for £1500 gets you 4kw. Then you need an inverter, these are around £1000. You would also need an electrician. So not including electric costs/cable etc, £2500 for a 4kw system that could save you £1728 a year if you are a heavy user of electric 24/7, that pays for itself in under 1.5years

How can we make this better?
Mentioned earlier, if we dont use the electric generated then it is lost. However if you have battery storage you can use everything you generated. The batteries are the really expensive part. £1500 for 5kwh of storage. 4 of these would store a whole day of summers energy. If your house is only using 4kwH a day, then you can run the house for 5 days with no sun. The system would keep itself topped up when ever the sun comes out. Certainly a very good thing to add to the solar system, however the cost is a real draw back. The price I put was for a Lithuim rack mountable battery, has temprature control built in, communications with the inverter. you can actually use a stack of car batteries instead as the inverters can charge lead-acids too.

FIT Payments
On new installations this cannot be applied for. However I wanted to pop this in here for completness. Every 1/4 of the year I need to give the solar meter reading to the energy suplier that I signed up for FIT payments with. Over the year I get around £700 back for the energy I have generated. This is from a generation meter, I could have used all that energy and not put any back in the grid, but still get paid the same.
 
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saleen 192

Core Member
Well explained Dan.
 

Will

Core Member
View attachment 165702
Can putting Solar panels on your house save you money?
Quick answer is YES.

Can they pay back what they cost in a reasonable time?
Well, this isn't as straight forward. This depends on how much energy you use and how much cost per unit it is. Having a 4kw system on the house it took around 7 years to pay for itself, and energy costs was around 16p per kwH. Things have changed since having the panels installed. Cost of electric is over double what it was. Also any new systems you dont get paid for selling back to the grid(I'll cover this later)

How much can it save?
The 4kw system on the house generated around 3600kWh over the year. Say if our energy costs is 48p per unit, that 'could' save you £1728 per year. The reason I say 'could' is if you dont use the energy you generate, it is lost. The summer months it can generate over 20kWh in a day, but if you only use 4kWh in a day, then the 16kWh left over is lost(unless you store it). So really you are only saving electric when you are using electric when the sun is out. Ideal to cook the roast dinner while the sun at mud day, as it would be totally free. Often seeing 3kw being generated. So boiling a kettle would be free at that time.

Before solar panels I was using 2200kWh from the grid. After installing panels I was buying in 1200kWh. The house is using power overnight, fridge, things on stand by etc, boiling the kettle when the sun wasn't out. Having a shower is 10kWh for however long you take. So there is plenty of energy being used that solar isn't helping with.

Costs
The cost of panels are fairly cheap, around £150 for a 400w panel which is 1mx2m. 10 of these for £1500 gets you 4kw. Then you need an inverter, these are around £1000. You would also need an electrician. So not including electric costs/cable etc, £2500 for a 4kw system that could save you £1728 a year if you are a heavy user of electric 24/7, that pays for itself in under 1.5years

How can we make this better?
Mentioned earlier, if we dont use the electric generated then it is lost. However if you have battery storage you can use everything you generated. The batteries are the really expensive part. £1500 for 5kwh of storage. 4 of these would store a whole day of summers energy. If your house is only using 4kwH a day, then you can run the house for 5 days with no sun. The system would keep itself topped up when ever the sun comes out. Certainly a very good thing to add to the solar system, however the cost is a real draw back. The price I put was for a Lithuim rack mountable battery, has temprature control built in, communications with the inverter. you can actually use a stack of car batteries instead as the inverters can charge lead-acids too.

FIT Payments
On new installations this cannot be applied for. However I wanted to pop this in here for completness. Every 1/4 of the year I need to give the solar meter reading to the energy suplier that I signed up for FIT payments with. Over the year I get around £700 back for the energy I have generated. This is from a generation meter, I could have used all that energy and not put any back in the grid, but still get paid the same.
Thanks for all of the info Dan 👍.
Certainly an eye opener and probably much more viable with energy prices going up so much. And they will again in the autumn apparently!
My choice would be solar panels with a battery system so none of the energy is lost. And very interested that you can use lead acid batteries, which are cheaper to replace and probably safer than Lithium ones. I can't stomach a full on solar installation at the moment, so as a sort of trial, I am thinking of a partial system, maybe just to run one room as a test. We sit in our conservatory most evenings with the lights and TV on, so a small system to just power that would save some money on the bill. I installed a 50w panel and charge controller on my boat. It always keeps all 3 batteries fully charged. In fact, people I know with sailing boats who have swapped their wind turbine chargers for solar because it is silent and takes up almost no space on the boat. (The semi flexible panels we use are bonded to the deck and can be walked on).
 

saleen 192

Core Member
Don't forget lead acid battery's give of gases and fumes.

Go hydro power Will you like water lol
 

Will

Core Member
Don't forget lead acid battery's give of gases and fumes.

Go hydro power Will you like water lol
Yeah, very true. I would probably have the batteries in an isolated enclosure and fan vented.
Haha good idea! I just need to move house to be near a dam! 😆
 

Will

Core Member
Yeah, very true. I would probably have the batteries in an isolated enclosure and fan vented.
Haha good idea! I just need to move house to be near a dam! 😆
I've been testing a solar panel for my brother in law. I made it up for him years ago for his old motorhome to keep the starting battery up during storage of the van. The idea was for him to plug the output of the charge controller into the van's cigarette lighter socket, then lay the panel on the dashboard in the sun. (And I had checked that the lighter socket was live to battery with the key removed).
Bit he said it didn't seem to work to well. I think the van wasn't parked where there was enough sun maybe. Also, a vehicle's alarm system and radio/clock backup will take a small amount of power. I have been testing it with one of my boat batteries and it seems to work OK, but is facing south with no obstructions.
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TransAmDan

Forum Admin
Staff member
Also remember if you cover a small peice of the panel, then the whole panel will have a lower output, also all others you have in series will also be reduced power even if they are in the sun. You only get as much as the weakest one.
 
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Will

Core Member
Also remember if you cover a small peice of the panel, then the whole panel will have a lower output, also all others you have in series will also be reduced power even if they are in the sun. You only get as much as the weakest one.
Thanks for the info. Yeah, having the panel on a the motorhome dashboard and not fully in the sun was probably why it didn't work too well. They have a newer motorhome now. What I will probably do is bond a semi flexible one to the roof and use a dual output charge controller, one output each for the cranking and leisure battery.
 
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