Planning Solar

Planning falls in to two categories, planning legal and planning the installation, here we are writing about the installation process planning.
But first lets deal with the legal..

Check Planning Permissions:

• Determine if your installation falls under permitted development or requires full planning permission.
• Consult local regulations and obtain necessary permits
• Planning permission is one side building regulations are the other.
  Conservation of fuel and power: Approved Document L – GOV.UK (www.gov.uk)

Planning your solar installation has a lot to do with scale, the bigger the system or the more you want, the more there is to consider; and with the larger investment it would be worth taking a deeper look.

How Much Power?

Solar is often seen as a “meets all needs” alternative, and for the most part it will not. Solar has taken off since the price rise of energy, but Having solar does NOT mean you will not be using the grid as many homes just wont have the space for the array that is needed.
If you want to have a quick and dirty look at what size your solar array could be you, need to measure your roof. An average panel is 177cm long and 105cm wide, there 420watts.
We will say your roof is 4.5(h) meters by 6.5(w), well that’s 2 panels in height and 5 in width giving a total of 10 panels and 4200w (4.2kw). Multiply the number of panels output, then multiply this by 4.

SUN hours.
Sun hours are not sunlight hours, but refer to the peak sunlight. this is in relation to fixed solar panels.
Winter is 2 hours, summer is 6/8 hours. but you can usually bank on 4 hours.
That’s 16.8kWh for 275 days, and 8.4 for 90 days. Both figures should be subject to a 35% reduction.
looking at winter (October to March), you would get about 5.4Kwh a day and for some of this time its half or less. During summer May to July you will have more solar than you know what to do with. which is why I call solar Feast and famine. You can read more on sun hour and solar array alignment here.

This image shows a 1Kw solar array in April (summer pitch easterly). As you can see the production is up and down. If we zoomed in we would see that the power jumps between 200w and 700w in less than a minute.
This is where a battery works out smoothing that power from the sun.

Combined power.

Solar and battery bring you combined power so that your not at the mercy of the clouds. it also opens up storage and peak rate stored power from the day to the night. Not only solar is a benefit as you can often have cheap rate power and charge the battery overnight. This can be used in winter, and paying 7 pence a KW is better than paying 30 pence.

The combined grid charge and solar makes a play off when it comes to installing solar panels. You could aim for total PV power, this requires space. but realistically you are going to have to compromise for at least 3 months of the year. But you could have 2Kw of solar charging a battery that is 15Kwh, it just mean that the solar will charge around half the battery and the grid can provide the rest.

Over paneling.

The subject of over paneling comes up a lot and many people do it. It is NOT ideal and can be dangerous. Over paneling is where you add more panels that the rated power. For example a 4 Kw solar array on a 3 kw inverter. You can on some, you cant on others.
You would consider over paneling for winter, and there are a few ways to do this.
You can have two arrays that are optimised for the season. you can have two parallel arrays.
you can combine arrays.
If you were to over panel, I would not, I would simply have a smart combiner box (coming soon)

The Smart Combiner.
The smart combiner controls the voltage and current to keep within the spec of the inverter, this is automatic so your house doesn’t catch fire.

The laying

The layout of the array is essential to make the most of the sun. Typically you would want two arrays. winter tends to offer less sun and the time is much shorter leading to famine. This relates to the array angle as roof angles tend to be far off the suns position. ( read more here) but a winter array can yield up to 50% More power in winter. if you went for a solar tracker your daily power would increase by 30% and the annual yield could be up as much as 70%. of course adding more panels or making a more effective system could result in less panels.

Inverter.
The inverter peak power should be calculated on your homes peak use, you can find this out on your smart meter.. However you may want to consider offsets as there is a limit for easy installation up to 3.6KW inverters and complex, over this amount. the forms and the installation are very different and the costs also change.
The smaller the inverter, the less power loads it will meet, so its important to start at the base load ( what your home uses 24 hours) and when your at home loads to begin to see any benefit.
If you have space for a larger inverter and battery then you may want to consider an inverter that’s nearer to the peak loads, this would have the highest impact on your bill.

G99 G98 or NO G at all?
Taxation and some form of costs are added to any installation, while the “club” prices for members is higher, you will have to ask yourself if you want to be a club member?
There is NO requirement to have a grid tied or parallel inverter.
a hybrid inverter with G99 will cost in excess of £1,600 to have installed. You could have one installed for around £450.

Grid tied hybrid inverters that work with the grid require testing and certificates to be installed as they work with the grid, you become part of the generation system and your out put must be as good as the grid. The big down side is that when the grid goes down so do you. (unless you have EPS)
Appliances, such as your TV cooker and microwave do NOT work in parallel with the grid and this is where Grid attached inverters come into play.

Grid attached inverters do not work with the grid sending out power, but they do take from the grid, They can pass through – send the grid directly to the load. or charge the battery. Here you do not export power but the power you generate is stored in the battery. You benefit from always on power and a lower cost.

There is not much to consider, you should take a look though the posts in February 2024 to see more information and details on each aspect of solar installation and environmental effects.

QUESTIONS ANSWERED IN THE COMMENTS.