Install Your Own Solar System
- Technology is evolving, and what was good yesterday may no longer be good today.
- So it’s good that Ronny Mergner from Fraron brings us up to date.
- Because our old solar cells sometimes don’t bring any yield, after the conversation, we also know why that is the case.
- We also learn why we recommends the Watt-hour EFX ActiveWire solar panels and why a good, large-sized solar charge controller is important.
- And by the way, the difference between MPPT and PWM controller, which is very important for us:
- The subject of shading in modern solar modules.
- And as if that weren’t enough, we’ll clarify how much solar system fits my battery.
- RV solar install has become not so difficult, you can do it yourself
Old solar cells and little yield
Amazingly, our solar system works. But sometimes, when the weather is nice and the sky is deep blue, the battery only gets 2 amps instead of the calculated 10 amps we expected.
And that is the reason why we have once again dealt with the subject of solar systems.
In the article How much solar system does I need, 5 years ago, we calculated how high our daily consumption is and chose a 200-watt solar system.
Today our daily consumption is significantly higher, and thanks to eBikes, notebooks, and smartphones, it is increasing rather than saving.
So it is only logical that we will upgrade.
Because according to Ronny Mergner, the old solar cells are defective. Cracked inside, they still generate electricity in cool temperatures, but when it gets hotter during the day, the broken conductor paths gape, and the current flow ebbs.
Modern cells are prepared for these temperature fluctuations and have a firmer surface. In the case of the Watt-hour EFC series, we have chosen reinforced rear walls to avoid these problems.0
Which solar panels
The decision was easy for us:
From recommended the Watthour EFX ActiveWire solar modules to us, and three of these 140-watt modules fit on our mobile home without the kayaks on the roof shading them because you should always pay attention to this: Shadowing – whether through roof hoods, satellite, or air conditioning systems significantly reduce the yield.
Quite apart from trees and lampposts – you have to pay attention to them when parking.
Flat or frame modules
The discussions are very controversial on the Internet, but basically, it’s more a matter of taste.
We have opted for flex modules because they look less bulky. In addition, they are walkable, and that is sometimes important for us when we pack kayaks on the roof.
The DIY solar system
Yes, of course, you can. Buy the solar cells, suitable cables, 4 mm2 is enough for a series connection (we still have 6 mm2), a good solar charge controller, Sikafklex or Dekalin for gluing, a roof duct, and then good weather and enough time.
Because even the professional needed 6 hours for us and the cables were already there, it’s better to count on double that if you don’t do it regularly.
Installation service from Fraron
We have often been to Fraron and have always been satisfied. Competent, not expensive, careful, and extremely friendly! There is also a lot to discover in the beautiful Spessart, and you can combine an appointment with Fraron with a short vacation. There is a parking space in the village, and while the mobile home is being cleaned up, you can try one of the many hiking trails or go out for a nice meal.
But of course, you will certainly find a good installation service in your area. As always, the problem is: finding a good fitter who also has an appointment-free! You may postpone your installation until autumn/winter when the installers have free capacity again.
How big should the solar system be dimensioned?
A solar panels system should compensate for the daily consumption as much as possible. But first, you have to know how high your consumption is.
In another article, we once listed our consumers. In the meantime, our favorite milk frother and the eBikes should have added a lot. You can find the whole article here: How much solar system do I need?
Be self-sufficient: ‘Consumption x days’ that I want to be free
Now, of course, the battery has to match. As is well known, we rely on lithium and now have 280Ah on board. Accordingly, according to the old calculation, we can be self-sufficient for 5 days without solar – but since we now also have to charge the eBikes, it is more like two to three days. At the moment, we calculate 90 Ah per day and sometimes 150 Ah.
With the new watt-hour 140-watt portable solar panels for camping, we get approx. 11 amps per panel at 12.8 V, according to the datasheet. With three panels, that’s over 30 amps. If the sun burns for 10 hours, 300-ampere hours (Ah) come together. Unfortunately, these are purely mathematical values.
Realistic values of our 3x 140-watt system:
Since the mobile home is rarely at the optimum angle to the sun, and as is well known, the sun is sometimes higher and lower, and a cloud can be seen from time to time, an average of 4-5 amperes per hour should come together at 10 hours per day per panel.
That’s still 40-50 Ah – a total of 120-150 Ah per day. It may even be over 150 Ah on very good days, but on bad days it will be much less. So our consumption is covered!
Real values with the 100-watt solar panel:
The manufacturers calculate with 400 Wh/d At 12.8 volts, that is 33 Ah. That is quite realistic. We came with our old system sooner to 25-28Ah per 100-watt panel throughout the day with clouds, high fog, and whatever is in the sky. Correspondingly less in spring and autumn. Of course, there are also good summer days when the yield can be significantly higher.
Rule of thumb battery size
You are well positioned with the rule of thumb: x1 – better x2 So 100 Ah battery – 100 watts on the roof, so you’re good to go in summer.
However, it is better to be on the move with the factor x2: 100 Ah battery – 200 watts on the roof, then you will also be in autumn and spring or far in the north or in countries where it is very hot (because then the solar yield of the panels from physical reasons again). And, of course, rely on lithium RV battery nowadays because, with an AGM or gel battery, you can only remove about half without damaging the battery in the long term.
The best case: daily balance consumption
This will not always succeed, which is why the battery is so important as a buffer. The worse the weather, the lower the sun is, and the higher you are in the north – or the south under trees in summer.
Many factors dilute the result
But there is just an as little point in choosing batteries that are too big as too small. Because the solar system should be able to charge the battery completely regularly. There is little use in having 500Ah batteries in the camper but only 100 watts on the roof. Just as little as 500 watts on the roof and only 100 Ah as a battery.
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- As beautiful as a solar system on the roof is, sometimes the solar bag, also known as a SunFolder, is the perfect addition.
- You can tap into the sun with a suitably long cable whenever you are in the shade or under trees.
- And when in doubt, it does a good job behind the windshield and cannot be stolen from there.
- We use an additional solar charge controller to ensure that both systems do not affect each other.