tarmac terror

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Can anyone help explain to me which way round a solar panel should be fitted - I don't mean the direction it should face.

The panel itself is rectangular, I have fitted it with its longest dimension facing up the pitched roof. Looking at some of the full roof installs on houses near where I live, I am seeing some panels fitted with the long side pointing upwards, some have the shortest side pointing upwards. I don't know if there are reasons for this beyond it being a best fit to cover the whole roof area.

The manual and background reading does explain the direction in which to point the panel, and the optimal angle, but it mentions nothing about whether the panel can be fitted any way round or not.

BMWhere?

shouldn't make any difference as the glass will not be polarised, so you could mount at any angle you wish, although most tend to stick to straight horizontal or vertical!

The optimal tilt angle will depend on your latitude and time of year, but most people just mount simply flat on the roof and make do. The direction should also ideally track the sun, but again a stationary mount is most common so as close to south (northern hemisphere) as possible.

tarmac terror

iTrader: (2)

Who said this forum was dead!!!!! Thanks for that BMWhere? - I worked out the added cost for tilting bracket or tracking mount wasn't justified, the gains for a single panel capable of 120W would be marginal.

It's on the roof, long side up and charging the battery in daylight. Some meters and switches ordered from e-bay to complete the install - it has been quite an interesting project so far.

dpb

We just got 100 w panel over xmas to safeguard electric supply to chicken hatchery - this is in zim
im pretty sure more than enough would come from just bolting it through the wall , but the primary concern is nobody steals it ( someone eloped with whole hot water system during the building the place , through the roof )
Probably less of a concern here

tarmac terror

iTrader: (2)

Have my shed over-watched by CCTV, but that's about the contents getting taken, rather than the panel itself getting taken. You considered shear bolts, and mounting in to masonry? Torque up the fastener until the head shears off, which leaves a button head which can't be undone. Wont stop a determined thief taking a grinder to the brackets though.

BMWhere?

That's why nobody really does it!

Currently building an energy efficiency house and going through the whole energy planning. Will have underfloor heating heated with a heat pump and ventilation system with a heat exchanger. 7KW of solar panels with battery storage and excess sold back to the grid. The house has been designed with an optimal roof angle to maximise the solar power. If the calculations are correct, I should be a net electricity supplier with a large surplus in the summer months and a small buy back in the winter. Also fitting a wood burner which is cleverly integrated in the ventilation system to heat the whole house, so can be further used to reduce winter electricity consumption and bring further savings.

German government is giving me nearly €20K in subsidies for energy efficient building and with a total investment of €25K for the energy system, I should easily recoup my investments within 5 years! The best part though is being a net electricity supplier, so I will have a monthly income rather than bills and essentially remove the risk of rising electricity prices!

tarmac terror

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Great project - half the fun in that for me would be tuning it all once built, to get the outputs you want as cheaply / efficiently as possible. You got a blog / thread on that as it progresses - would be an interesting one to watch.

ALi-B

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hedgecutter

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I'm doing something similar, but on a listed building, so with various restrictions, and limited grants. I'm also limited by the local transformer capacity.

BMWhere?

I thought about blogging it in the beginning, then quickly realised I've no time for it!

Its all quite fascinating though! Building using a pre-fab company local to me here in Germany. The pre-fab builds are so advanced now, they can achieve far greater energy efficiency for a fraction of the costs compared to traditional builds. I also have full design flexibility, so I'm really building "my" house! Its a wooden construction with a traditional plaster finish, so from the outside you couldn't tell the difference from a traditional build. The wood is all machine cut to within 1mm tolerance. The windows are delivered before they start construction, so the holes for the windows are cut to fit the delivered window frames perfectly rather than the typical oversized holes which are then padded to the windows which is a huge point of energy losses. Production is in a clean, dry workshop with an army of seemingly very happy workers who were all very friendly when I did a factory tour. Will take 6 days to manufacture before being packed on a truck and shipped to the building site, where on site assembly takes just three days. Fitting out is then completed within a month, then depending on the weather at the time I can either move straight in or have to wait for another month or two for everything to dry out. I'm also building a cellar (pretty standard over here), that is also pre-fabricated concrete walls with a concrete base laid on site. Celler construction starts one month before the house build and the house plans will be adjusted to the finished cellar measurements to ensure a perfect fit!

The German government has a really great incentive scheme for energy efficient new-builds which is also linked to government loan for up to €100,000 - In Germany, its typical to split your mortgage across multiple lenders! The scheme is based on achieving energy savings related to the average German house which gets re-assessed every few years (last time 2016) to force a continued energy saving. There are various levels; KFW70 is the minimum build standard, then there is KFW55, KFW40, KFW40+ and Pasiv - the number stands for the % of energy needed to heat the house based on the current average - So essentially, the minimum build standard requires you to save 30% energy compared to the average. I'm building to KFW40+, so a 60% energy saving over the average, the "+" being that it's fitted with renewable energy source which will supply more electricity than you consume. A "Pasiv" house requires that your only active heating source is a wood burning fire which heats water, otherwise all heating has to come from the sun through clever windows which let heat in but not out and solar heating panels on the roof. My house will actually be built to "Pasiv" standard, including the clever windows, but as I have a full heating system, I only qualify for KFW40+. Each standard affects the level of grants you can receive, the interest rate you get on the loan and your council tax rate afterwards. To qualify, I had to do a "KFW" plan to detail the building standard and envisaged energy consumption before applying for the finance. Once the building is completed, I then have to pass a "blower-door" test, where they attach a big fan in the place of the front door and pressurise the house to measure how air-tight it is. Once the test is passed, then the grants are released in the form of a loan repayment on the government credit. I should get €15,000 for the KFW40 and an additional €5,000 minus the cost of the KFW plan (~€600) for the solar install

The total build cost is about the same as building to the KFW70 standard using traditional construction techniques without solar and would get no grants (you could still get the €5,000 if you fitted solar). So essentially, I'm saving 30% energy for no additional outlay simply by using a modern construction technique. Plus I'm saving myself a countless amount of stress by not having to deal with tradesmen and all the various construction problems! No wonder nearly 40% of the houses being built in Germany now are pre-fabricated. There is a lot of skepticism about building pre-fabricated houses, so many people still build traditionally as they see it as a lower risk, plus a large percentage of plots are sold to developers who still build brick houses, so the purchaser often has no choice anyway. Still, Germany is leading the way with pre-fab building and energy efficient housing - the UK has a lot of catching up to do in this area, but without any financial incentives from the government, progress will be slow!

Puff The Magic Wagon!

iTrader: (2)

Wow @BMWhere - yes indeed the UK has a lot of catching up to do!

I'm in the process of converting an old stone barn, though in the end only part of the back wall will remain (and a dividing internal) as the rest is ropey, so will come down and be replaced with modern blockwork/insulation with stone facing. Floor is being dug up/replaced and will have u/floor heating. Triple glazing throughout & new (reclaimed slate roof with insulation). Will probably have an ASHP and solar water feeding into a heat store + a wood burning stove w/back boiler. 8kw solar in the garden on a scaffold frame - I am also limited by local transformer capacity but you can cap how much you put into the grid. Might do a GSHP as I have the land for it but depends on budget in the end (I can get the ASHP essentially free).

Aim is to have as little outlay on energy as possible in the future.

BMWhere?

Thanks!

As I understand it, for renovation work, solar water heater panels are a far more cost effective solution than fitting solar electric cells.

If you are heating water with electric, then the best way is via an air to water heat pump, but for most renovations that is not possible due to space restrictions, hence using solar water instead.

If you have room to fit a heat pump, then that is the way to go!

Puff The Magic Wagon!

iTrader: (2)

I have an ASHP on the main house (it will be holiday rental once conversion completed) and it costs a friggin' fortune in electricity. House is cavity wall but had a fire in the 70s and was repaired badly, leaving crap in the cavities that breach the gap, so I can't add insulation but have done the best otherwise (roof, windows, big pipes/rads). If I was living there full time, then I would be looking at 20,000+ kwh a year and even part-time it was 9000 kwh last year. I try not to use the ASHP for heating and rely on a wood stove.

For the renovation I'm fortunate enough to be able to use modern construction for nearly all of it, so it will be well insulated. We get RHI over here and there are some schemes around that you can get an ASHP and Solar Water for free as long as you let them have the RHI. That suits me as my total budget is minimal and I am doing as much of the work as possible. Solar electric is to provide power for the ASHP during the day + other amenities. Solar water for hot water with the back up of the stove and/or a solar immersion (why not use solar to top up HW if not being used elsewhere). If I had the money then I would have chosen a GSHP instead as much more efficient.

I'm hoping that the whole thing will not require too much energy anyway as should end up being less than 90 sqm over 2 floors and super insulated.

BMWhere?

Always a problem with old buildings that you waste so much energy through the building itself. Even new houses with traditional build are pretty inefficient. Pre-fab building let's you get the best compromise between cost and energy efficiency.
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​​​​​​On a refurb, there is not much you can do other than clad it and add roof insulation. Even with new windows, you'll get big losses around the frame gap.

I love the idea of a GSHP, and for a refurb it could be a great solution, but for a new build to the highest energy standards, you'd probably never recover the investment costs Vs an ASHP (at least I wouldn't in my remaining lifespan!).

The company that's building my pre-fab have an awesome solution in their 7 storey fitting-out centre. They have a huge water tank in the basement and use a water source heat pump. Over the winter, they great from the water in the tank which eventually freezes. In the summer, they then reverse the system and cool the building storing the extracted heat back in the water tank ready for hearing again the next winter. Combined with solar on the roof, they are essentially heating and air conditioning a seven storey commercial building for free and with zero emissions! If only all businesses did that, we could solve global warming right there!

RobsyUK

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