Good, unbiased views/advice/info on solar power

[Kistelek]

My bungalow has a mass of south facing roof and is currently Economy 7 electric only heated with ASHP. I'm interested in getting solar power, along with something like a Tesla battery to make the most of my free energy and, with the latest software it seems, cheap night time power. We don't have any electric vehicles yet but they are on the cards when we're up to replace cars/van.

What I'm after is a good, unbiased source of information on what's out there, what to look for, what to avoid, and some info about how it all works, how it's fixed to the roof for example, what the pitfalls are, all that sort of thing. Everywhere I've looked appears to want to flog me something or treats me like an absolute buffoon, which I'm not.

I'd like to know what the art of the possible is and what's sensible to aim for.

 

[JohnW2]

My bungalow has a mass of south facing roof and is currently Economy 7 electric only heated with ASHP. I'm interested in getting solar power, along with something like a Tesla battery to make the most of my free energy and, with the latest software it seems, cheap night time power. We don't have any electric vehicles yet but they are on the cards when we're up to replace cars/van.

As a general concept, I think solar power is (or was) probably only (sometimes) a worthwhile financial exercise because of unrealistically high 'feed in tariffs' (which are subsidised by all those without solar power).

More specifically, I don't think you should hold any great hopes of solar panels in the UK ever having an appreciable impact on charging of an electric vehicle.

Others will probably have more useful and/or specific comments/advice.

Kind Regards, John

 

[ericmark]

For solar electric power to pay for it's self depends on government fixed tariffs,

OK I know Australia, but it shows what they do.

It must depend on where you live, daughter has hot water from solar in Turkey works fine, father-in-law has it in North Wales and only works in summer.

Some electric panels are more sensitive to others, and there is a debate to East and West or just South facing, it seems installers can't agree if the 7 kW refers to what the cells will produce if aimed at sun, or what they will produce on your roof, East/West the peak output for set amount of cells is clearly less, but it will produce for longer and at a more constant rate.

Once the limit is reached then you hit next bracket so your pay is less, so if 7 panels facing south make 7 kW and 10 panels facing East/West also peak at 7 kW you can make more money as producing power for longer. If rate did not drop after 7 kW then clearly better to all face South. As said all down to tariffs, so having a battery does not really help, yes you could store power midday and then release in the evening but that would not allow you to mount extra panels and stay within the tariff band.

So solar panels are not worth fitting unless you get the daft tariffs offered by some governments, so if fitting to make money, then it's down to how the installer rates it when sending in paperwork on how many you can fit and facing what direction.

 

[motorbiking]

Forget the Power wall, You can buy devices that trickle the hot water heater which is a much better way of storing your energy. Also depending on the size of the install it probably will make a difference to an EV, unless you are looking at a Model S etc. I was one of the early adopters and reckon we'll make 8% easily.. My 2.5kw system is quite old now, but still pushes over 2kw/ph peak most sunny days.

 

[bernardgreen]

Some of the sales to domestic customers are extremely optimistic about the watts per square metre of panel. Documents in support of planning applications for solar farms give lower figures for kW per square metre of panel.

As Eric mentioned the Feed in Tariffs ( FIT ) are daft. Paying the owners of solar panels more per kWh than that kWh was sold for is commercially stupid. ( Unless there is a hidden agenda to get panels on several roofs to make it seem sensible to the masses ).

A aquaintance fitted solar panels at a cost of several thousand pounds and then claimed that the electicity supplier was paying him "a good income" and total payback of the installation costs was not too far away. ( he may have been boasting ) Then things changed. He had to move home due to his employer relocating. Buyers were put off by the panels on the roof and no transferable FIT. The panels could not be fitted on the roof of the new house due to planning constraints.

 

[motorbiking]

FITs are transferable as long as they are included in the property sale and owned by the vendor. My biggest concern was whether the inverter would last.

 

[ericmark]

FITs are transferable as long as they are included in the property sale and owned by the vendor. My biggest concern was whether the inverter would last.

Not heard of many inverter failures, however an inverter likely has electrolytic capacitors in them and they do have a limited life, so one should expect to have it repaired or replaced a few times in 25 years.

Selling father-in-laws house at moment, the water solar panels have raised the energy rating of the house, so made it easier to sell.

 

[motorbiking]

Solar water is vastly more efficient if you are paying eco-7 to heat hot water. A 2kw system would be about 5 x smaller than a PV.

 

[JohnD]

but if you are lucky enough to have gas, the cost of hot water in the summer is so low that solar will save you next to nothing, and will probably not achieve payback.

Things that have to run on electricity are where solar can make real savings.

 

[motorbiking]

I'm not convinced - Its pretty easy to make a solar pre-heater, the controls are pretty cheap now. You can get one installed for <£3k. The price of Gas seems to only be going one way and our currency the other.

 

[JohnD]

I don't know how much gas your house uses for water heating. In summer, ours uses 0.6 cu.m/day. That's' about 6.7kWh. Our current price is 2.62p plus 5% VAT. So a usage cost of 18.4p/day

It would take a very long time to save £3k at that rate, even in the unlikely event that solar halved our summer usage. Much more than a lifetime.

 

[Bosswhite]

Some of the sales to domestic customers are extremely optimistic about the watts per square metre of panel. Documents in support of planning applications for solar farms give lower figures for kW per square metre of panel.

As Eric mentioned the Feed in Tariffs ( FIT ) are daft. Paying the owners of solar panels more per kWh than that kWh was sold for is commercially stupid. ( Unless there is a hidden agenda to get panels on several roofs to make it seem sensible to the masses ).

A aquaintance fitted solar panels at a cost of several thousand pounds and then claimed that the electicity supplier was paying him "a good income" and total payback of the installation costs was not too far away. ( he may have been boasting ) Then things changed. He had to move home due to his employer relocating. Buyers were put off by the panels on the roof and no transferable FIT. The panels could not be fitted on the roof of the new house due to planning constraints.

The above is the main problem the panels are fixed for a period of time (about 20 years or so) so potential buyers are put off, plus if the roof wants repairs it is the owners responsibility to remove and replace and still have to pay in the "Feed in Tariff"
Home owners are basically renting out their roof and are bound by conditions by the Company

 

[StephenOak]

Some of the sales to domestic customers are extremely optimistic about the watts per square metre of panel.

In another forum I had a discussion with someone who said that no solar panels ever needed cleaning because his system had not been cleaned in the years since it was installed and he was still getting 105% of output from it.

I asked what this 105% figure meant and he (I think genuinely) could not do so. I explained that a, say, 3kW system will only deliver any electricity for <12 hrs/day (over the year) and so has to be less than 50% efficient on that alone, leaving aside low output early & late in the day. This still did not convince him.

After a bit more questioning I worked out that the vendors had said a 3kW system will give him, say, 10 kWh per day over the year and he was getting 10.5 kWh.

The vendors may have made a genuine calculation tailored to his house and the historic local weather pattern, or they may have just given a very crude estimate. What they had not done was explain to him how such a system worked and what its limitations were.

 

[JohnW2]

FITs are transferable as long as they are included in the property sale and owned by the vendor. My biggest concern was whether the inverter would last.

My understanding is that one problem arises when people have solar panels (which are never owned by themselves) fitted for little or nothing by third-party companies who effectively take out a ('perpetual' or, at least, very long-term) 'lease' on the roof of the property - a situation which can be pretty off-putting to future potential buyers, since the potential liabilities (e.g. removing and replacing the solar panels if roof work is required) not only 'can' be transferred, but will be transferred to any buyer of the property,

Kind Regards, John

 

[bernardgreen]

fitted for little or nothing by third-party companies who effectively take out a ('perpetual' or, at least, very long-term) 'lease'

Exactly the same as selling the house with a sitting tenant.

When the house owner has bought and owns the panels and paid an installer to connect to the grid there are still problems with selling the house and panels as a "package".