Looking for help on the subject of electricity in the motorhome? You want to be independent of the power outlet for a few days or longer? You are planning a new vehicle and are looking for an energy concept and you are still missing essential numbers? Welcome, here you are exactly right!
With this article, I would like to give you an overview of the topic “electricity in the motorhome.” It will take some time until you have read everything – sorry, I have already tried to address only the most essential topics without unnecessarily going into great detail. But with luck, I can help you with this text when planning your new energy concept.
The “gas-free motorhome” seems to be a trend. Gas free is usually called – electricity takes over the work, which is done generally by gas. What is to be considered, I will clarify the beginning to enlighten you then in the course of battery technology, solar (photovoltaic) and other charging options for RV batteries.
Table of Contents
- The power supply in the motorhome, what are my goals?
- Motorhome Gas-free?
- Gas – a great source of energy in the mobile home
- Motorhome heating – with electricity instead of gas?
- My conclusion on the heating in the motorhome
- Cooking with electricity instead of gas
- Mobile home refrigerator with electricity instead of gas
- 230V fridge in the camper
- Power consumption of 230V devices in the motorhome
- Conclusion: electricity in the mobile home
- Inverter/inverter in the camper
- Design of the battery in the motorhome
- Charging the battery in the motorhome
The power supply in the motorhome, what are my goals?
- Gas-free AND self-sufficient mobile home
- Heating with electricity
- Cooking with electricity
- Cooling with electricity instead of gas
Further topics about motorhome power supply:
- 230V inverter/inverter
- Design of the battery capacity in the motorhome
- Planning tool for power consumption in the motorhome
- Loading by charge booster
- Solar system motorhome
- How should I design my solar system?
- Electricity generator and fuel cell
Again and again, I get inquiries from customers who want to build a gas-free motorhome. The reasons for a mobile home without gas are manifold. If some people are just afraid of gas, others will shy away from you because they want to extend their vehicle by installing a gas system and others believe that there is no gas supply outside of the USA.
Are you building a camper right now? Gas supply in the motorhome is neither unusually dangerous, nor is it difficult to install. The installation of a gas system, you can even do it yourself; only the acceptance must be a certified gas tester. If you inquire in advance and also include the gas detector in the planning, then I see no problem with secure gas supply in the camper.
The situation is different for long-distance mobile homes, which still want to heat and cook outside of Europe without gas supply. Here, electricity or diesel can be an alternative – but not every long-distance traveler puts so much money in his electrical system, and the travelers used to cook with the VW Bulli – how did it go so entirely without electricity? Here I lack the experience so far because I move only in Europe and here the gas supply is more than sufficiently good. Corresponding world travel forums will certainly help here.
Gas – a great source of energy in the mobile home
Gas (propane or butane) is an excellent source of power when it comes to cooking, baking, heating and cooling. Per kilo of gasoline, you get a lot of energy. Gas burns clean and odorless and is available throughout Europe.
I suppose the fear of gas comes with most of the ignorance. Gas is invisible and can burn. In exceptional cases, even explode and there are many afraid of.
Funnily that’s not the case with electricity. Here, many consider themselves a specialist, and when I see so many electrical installations, I sometimes wonder why the car did not burn down a long time ago?
Gas in the motorhome is safe
Gas is very reliable – or have you ever heard of gas accidents? Driving with the motorhome on the highway and it is much more dangerous than a gas system in my eyes.
Gas can be stored very flexible! Unlike batteries, there are very different types of storage options for gas. Swap bottles, which can be exchanged in DIY stores or campsites for full bottles. Or tank bottles that also fit in the gas box and can be refueled with LPG at the European filling station network, or permanently installed gas tanks of various sizes, which are also filled with LPG at the filling station. There are also combination solutions, such as exchange bottles and an LPG gas tank.
Gas is an excellent source of energy and is light in comparison to stored electricity in batteries. Here’s an example: One kilo of gas has the energy content of 14kWh. A gas bottle with 11 kilos of gas gives energy for 154kWh!
To store this energy in batteries, it requires 61 pieces of 200Ah lithium batteries, which already have a much higher energy density than lead-acid batteries. In addition to the initial cost of 170,000 euros (discounts not included in this purchase amount), the weight of 2.5 tons is not to be despised. Incidentally, lead-acid batteries would cost much less here, but at least double that.
These numbers illustrate very clearly how high battery power is and what ridiculously small amount of energy is in such a 100 Ah battery.
Weight from gas to electricity – energy density
|gas||GEL battery||Lithium battery|
|1 kilo||14kWh||0,041kWh||O, 082kWh|
My gas tank can hold 36 kilograms and is enough for 14 months if I make warm water in the winter for about 3-4 months and cook all year round.
Motorhome heating – with electricity instead of gas?
Yes, I have a heater in the motorhome and operate this again and again over the inverter with battery power. I have often written this in my blog and some seem to think that I could use it to heat my mobile home with electricity even in winter. That’s not entirely true. I use fan heaters more often in the transitional period when the weather is already sufficient solar yield and it is still too warm for the wood stove, but too cold in Womo. To increase the interior temperature from 15 to 20 degrees, it takes about a kilowatt-hour of electrical energy from the batteries. At 3.5kWh storage capacity is quite acceptable consumption, which I get back on my 950Wp solar system in the fall and spring and loose again.
In winter, however, it requires a multiple of heating energy to keep warm at low temperatures a motorhome. I once connected a power meter to the shore power cable and measured the consumption. For the 25kWh I consumed in a day of heating current. Heating the mobile home with electricity is certainly not such a good idea.
Why do I write such numbers? Anyone who was on the road in winter with the motorhome and had to heat it knows for sure that such a gas cylinder at minus temperatures quickly times after 3-7 days is empty.
Sure, only a few people come up with the idea of heating an RV in the winter with electric heating, powered by batteries instead of gas. A diesel heater is a much better way if it should be without gas. Oh, forget the tealight heater! That’s game stuff.
Randinfo to diesel heating in the motorhome
I would prefer not to do a camper diesel heating – too high is the probability of failure. Many campers with such a diesel heater in the motor home tell me about failures. The cunning ones know how to repair the heating themselves, and have space heaters or at least spare parts to help themselves in times of need.
A Trauma diesel heater can only repair very few Trauma service stations in the south of Europe. I am mostly missing suitable spare parts or just the whole expertise on these devices.
My conclusion on the heating in the motorhome
In summary, I would like to say that gas heating is the most uncomplicated and failsafe heating solution for a motorhome. For gas heating, I also operate a wood stove in the motorhome. I have a failsafe heater with the wood burner and can extend my independence of gas to over a year, since I only need gas for cooking and occasionally for the water boiler. Both together is the right solution for me, which also brings a lot of romance through the wood fire with it.
Hot water with electricity
Hot water can be produced with a corresponding boiler in 4 ways.
- gas boiler
- Furnace in the combi heater with gas or diesel
- Electric kettle (e.g., Elgena)
- Hot water boiler with a heat exchanger (for engine cooling water, wood stove or solar collector on the roof)
Since I have installed the Trauma combi heater C6002 EH in my motor home, I can heat both with gas or electricity with the water. In the summer, when I harvest enough solar power, the water is naturally heated electrically. But I remain independent of the bad weather, by switching to gas operation on rainy days in winter and then taking a shower without additional power consumption. I like the solution very well.
Flexible hot water boilers
There are hot water boilers in various sizes that can be heated with different types of energy. Elgena electric boilers are super flexible and can be configured according to your wishes. For example, the pot can be equipped with a 12V, 230V, or a water heat exchanger.
The idea of use: The motorhome for the motorhome heats up while driving with engine heat and then keeps warm water ready for 24 hours. With 230V, the boiler can be heated on the Stell- and campsite, and if it gives the battery, can also be produced with 12V hot water. If I were to build a new motorhome, I would think about this solution in conjunction with solar thermal.
Cooking with electricity instead of gas
When cooking with heat, the whole thing looks different again. Even I thought long to replace my gas hob with an induction hob. Why I did not do that, however, has the following reasons:
- Cooking with electricity requires a lot of battery capacity. Frying a steak alone consumes 30Ah of battery capacity. Consumption values for the pot roast I still lack but are replenished.
- Reason 2 is the first reason, because I want something every day, even if it rains and the solar system, therefore, provides no electricity.
This is exactly where my problem starts when customers ask me what I would recommend being able to cook with electricity. Everyone cooks differently and has different preferences. For years, I served a steak every few days in the pan, in between there was pasta with sauce XY. Others conjure up a three-course menu in their kitchen every day and bake cakes in the Omnia oven. Ok – the Omnia does not go on the electric stove in the motorhome then no more, it will need a proper oven.
Oven for the mobile home
The oven falls into the Nice-to-have category for me. If there is enough electricity, it can be baked, if not there is food from the gas stove. In the greatest need, I can also operate the oven on the generator – which would then no longer correspond to the project target “self-sufficient mobile home.”
Interim conclusion cooking with electricity in the motorhome
Cooking with power is entirely possible when the wallet is playing and you are ready to make additional compromises. When the battery is empty, the kitchen stays cold, or you need an alternative cooking option. This raises the question – do I want to lug a gas cooker to the induction hob? Where do you get gas bottles for this cooker abroad?
Mobile home refrigerator with electricity instead of gas
Compressor refrigerator or absorber refrigerator? The big question. In a vehicle without gas system and diesel heating, the answer is clear – this is only a compressor refrigerator.
If a gas system is installed, the response will be more difficult and both ways, both absorber and compressor refrigerators, may be the right choice.
An absorber refrigerator is a pure energy destruction machine with a spectral efficiency. BUT – because the energy content of GAS is so high, the consumption of the gas refrigerator is not so significant. An 11-kilo gas cylinder lasts for 4-6 weeks with a gas refrigerator.
Speaking in numbers, you can see much more clearly what I mean: A gas refrigerator consumes 2-3kWh during the day, while the compressor refrigerator often only permits 0.5kWh during the day.
Nevertheless, this power consumption must be covered with something. First and foremost, with battery capacity, which has to be recharged through different possibilities.
The compressor refrigerator is excellent in the summer; the sun produces a lot of excess solar power and the fridge with supercharged cools much better in the heat of the day than its brother with the gas operation. Unfortunately, the compressor refrigerator consumes power even in winter, where the solar system may not be able to supply any electricity because it is snowing or continuously raining. This is where battery capacity comes into play! My Vitrifrigo refrigerator approves itself on the day 500-700Wh – indeed, there are more economical models, which cost twice as much in the purchase.
230V fridge in the camper
If we are already at a price. Buying a 230V compressor refrigerator and then running it through the inverter is, in my opinion, saved at the wrong end. The inverter also costs money and lends itself a bit of power every hour, just so that it can provide 230V so that the refrigerator can start up when it wants. 12Ah so go on the day only for the inverter on it, in addition to the power consumption of the fridge.
Of course, if you need a refrigerator only in the summer, this solution might be an option and those who only have power on parking lots, anyway.
Power consumption of 230V devices in the motorhome
From my experience with 230V tools, I would like to offer you a basis for planning your power supply and below some numbers.
|Fully automatic coffee machine (Saeco)||2 cups 0.44 liters||50,4Wh|
|35 minutes cooking||Vegetable pan without meat||550Wh|
|water heater||From 20 ° to 40 °||500Wh|
|35 minutes oven 1350W||Grill chicken||600Wh|
|Refrigerator 12V||Per hour at night||25 Wh|
The power consumption in Wh (watt-hours) makes it comparable for all battery systems. If you want to know the required amp hours, you have to divide the Wh by the current battery voltage. For small consumers, I would expect at 12V lead acid batteries with 12.4V and with large loads over 1000W possibly even only with 11.8V.
Conclusion: electricity in the mobile home
A motorhome without gas is great, but you should consider, with which financial expenditure you buy this luxury. And one thing is never to be avoided:
If you only have one day longer rain than the battery capacity is sufficient, you need an alternative energy source. Be it a generator, an alternator, or just a shore power. Of course, gas is running low, but here you can plan your independence by correspondingly large storage much better and cheaper than electricity.
My rational solution:
Cooking, baking and heating with gas in the mobile home. Possibly. A wood stove, if space gives it. Electricity only for small consumers and maybe the coffee maker or kettle.
This is how I do it:
Gas/electricity mixed solution – depending on weather conditions. With 36 kilos of gas, I’m 14 months independent. It can be assumed that during this time, a gas filling station can be found. But with 36 kilos of gas, I can heat through 2-3 weeks in winter, if need be, if I can not get any wood for the wood burning stove. If I can get shore power, I can heat entirely with electricity, cook, bake and prepare warm water. That’s how I survived my first winter in a mobile home in the USA. I had free power and could only supply my hut with electricity without gas consumption.
Inverter/inverter in the camper
230V power in the motorhome, as at home from the socket. Luxury is becoming more and more a standard feature in motorhomes. But many wonder why the batteries are always empty. Or worse, if after a few years, or even months, the cells are broken. But why is that?
High currents at the inverter
Coffee maker, fan heater, kettle, toaster, hairdryer and the Thermomix are all appliances with a heater. One thousand watts of power consumption are in the coffee maker average, hairdryer and kettle could even 1600 watts approve. A suitable inverter is quickly bought, the offered power classes for the 12V network go up to 3000W (Victron even 5Kw).
Example hair dryer:
1000Watt to 230V are 4.3A current consumption from the 230V mains. At the 12V input from the inverter is the power consumption but at good 90A !! That’s why the parts have such thick cables! The 90A discharge current must first apply a battery and this is where the problem begins:
The problem is the battery; it has to be able to supply the inverter with the necessary power. Lead-acid batteries quickly reach their limits here (see also the section “Lead-acid batteries and the currents”). Depending on the type of battery, you should not exceed a certain amount of current to ensure long battery life. Specifically, for lead-acid batteries, 0.2-0.3C should not be exceeded, which corresponds to 20-30% of the capacity.
So it takes a lot of battery capacity to power powerful electrical appliances easily. For 1000 watts 330Ah should already be available in the best AGM batteries for RV. Otherwise, you will not long enjoy your batteries.
Most of the premature failures of AGM and lead-acid batteries in recent years have come from customers who have discharged their batteries with high currents. Therefore, my tip: For high currents prefer to use lithium batteries, which interfere little because of the low internal resistance too high discharge currents.
Design of the battery in the motorhome
Somewhere the electricity for the electrical consumers in the motorhome must come from, and usually, this is done via batteries. Like the starter battery for the engine, there is a similar battery for the living area in the camper. This battery ensures that the water pump, light and heating work even without the connection to the socket.
If you want to be self-sufficient (regardless of the power outlet), there are different solutions. Everything is somehow connected and “the one” ideal way does not exist since everyone uses his vehicle differently. For example, I stand in one place for a long time and yet have to cover my energy consumption, others drive every day and like to park in the shade — two different energy concepts.
Which camper battery should I buy? Lithium or lead?
The more often and the longer the camper is in use, the more worthwhile is a lithium (LiFePO4) battery. Even if power consumers are to be operated with high power, lithium is the better choice.
Lithium is undoubtedly not the cheapest choice for the 6-week vacation of a motorhome. Also, whoever is on the electricity on parking lots, can confidently fall back on lead-acid batteries. However, for those winterers who are off-shore for 3-6 months a year and care about solar power, the Lithium LiFePO4 battery is the best choice.
Pros and cons of battery types in a nutshell
A lot of battery capacity has a high weight – with a lithium battery can save 50% and more of the importance compared to lead-acid batteries.
|Wet battery for campers|
|Wohmobil GEL battery|
|AGM camper battery|
|LiFePO4 battery for campers|
What in the world is a solar battery?
A battery optimized for solar power could be thought like this – but what happens if I charge a solar cell with shore power on the pitch? Or even with the charge booster while driving? Is solar power something other than shore power?
My tip: Stay away from such offers! Here one focuses on unsuspecting customers, who believe that they get excellent goods with exceptional performance for little money. Yes, they still exist, the Billigheimers who do not dream of there being any reason why brand manufacturers are selling good batteries for significantly more money.
Lead-acid batteries and the currents
In the motorhome is a 90Ah GEL battery installed and you now want to install a 2000W inverter for the Senseo coffee machine. If that works out? I say, no!
Depending on the battery type, sure current loads should not be exceeded. For 12V lead-acid batteries, one can say that the more stable the battery is, the less power it can handle. A classic example is the starter battery: Due to the thin lead plates, it can deliver extremely high currents for starting, but it can not discharge deeply. The stark contrast is the lead-acid battery with GEL. Deep discharges up to 50% do not hurt her, but high currents should be avoided here to ensure long battery life.
My recommendation for the maximum currents of batteries:
Common is the unit C. 1C = amperage = capacity (eg for a 100Ah battery, 1C would be 100A discharge current)
|Battery type||discharge||charging current|
|Lithium battery (LiFePO4)||3C||0.5C|
Consequently, some battery capacity is needed to operate sure consumers. Here is a table where you can easily read it:
|Electric kettle (800W)||60Ah||240Ah||400Ah|
|Coffee machine (1000W)||60Ah||330Ah||500Ah|
These numbers serve as a guide to getting the best out of the battery. If the recommended discharge currents are exceeded, the battery is not broken the next day.
As you can see here, lithium batteries are great when high discharge currents occur. Even the small 60Ah lithium battery can theoretically deliver 180A discharge current and power a 1800W induction hob. In practice, this makes no sense, because, after 20 minutes, the array is empty. You can also read our Best Trolling Motor Battery for the Money Guide to choose the best trolling motor for your boat.
How much battery capacity do I need in the camper?
An excellent value is for the average consumer if you can stand for three days without recharging the battery. With a solar system, the service life can be extended accordingly. Ideally, you will even become completely independent of it. For long-term travelers and Dauerfreisteher, it is not a mistake, if you can also bridge for five days without charging current – that brings more independence.
Determine power consumption
To plan the battery capacity for the motorhome correctly, you should, first of all, determine your power consumption. If the power consumption is known for 24 hours, this can easily be extrapolated to three days and then the required capacity can be selected by battery type.
- For lithium batteries: It does not hurt if the battery is completely discharged. Therefore, you can start here for three days easily 80-90% of the battery capacity.
- For lead-acid batteries: Lead-acid batteries respond to deep discharges with a short life span. Therefore you should try to discharge the batteries only up to a maximum of 50%.
So it is here with lead batteries significantly more battery capacity than lithium batteries needed.
Charging the battery in the motorhome
To get the motorhome self-sufficient, i.e., to be able to stand longer without shore power, somehow electricity must be generated. There are various ways to do that, which I will discuss in more detail below.
- Charge the battery with a charge booster
- Charge battery with the solar system
- Charge the battery with a fuel cell
- Charge the battery with an emergency generator
Self-sufficient with a charge booster
Battery-to-Battery (B2B) Chargers, colloquially referred to as charge boosters, serve as the name implies, to charge a battery from a second battery – with charging characteristics. Charging boosters supply power from the starter battery and charge the living area battery. The voltage of both batteries is continuously monitored and the charging current adjusted accordingly. Thus, neither the starter battery can be discharged, nor be overcharged the living space battery.
Charge boosters pay off for long cable runs and, above all, for some new vehicles. Because many motorhomes from Euro 6 have a regulated alternator and it comes after a short driving time only a little charge current to the body battery. You can quickly work around this problem with a charge booster. What exactly charge boosters do, you can read here.
When does a charge booster make sense?
If you drive a lot, and rarely stay long in one place, regardless of the weather would like to be, with a charge booster well advised. The battery capacity is designed for maximum life in one place and the charge booster ensures the fast charging of the living space battery while driving.
Attention: Charge boosters also take several hours to charge a lead-acid battery fully. A pure battery charging without shore power connection is therefore recommended only with lithium batteries, as these batteries are not always fully charged must / should.
Vehicles with a regulated alternator and lithium battery system should be equipped with a charge booster. The down-regulation of the alternator voltage has the consequence that – due to the higher energy of the lithium battery – this rather unloads while driving, rather than being charged.
How active should the charge booster be?
For lead-acid batteries: maximum 30% of the capacity as charge current. So 30A charge current with a 100Ah battery. This would be enough of the 25A charge booster. I know that I mentioned different numbers at the top of the table – sometimes you have to live with compromises.
For lithium batteries: Not more than 50% of the capacity (0.5C) as charge current. That would be 45A for the 90Ah LiFePO4 battery. Here you can also assume that the 90Ah lithium battery is fully charged after 2 hours of driving time.
Self-sufficient with the mobile home solar system
Solar on the motor home is the most common solution to recharge batteries regardless of shore power. But there are some things to consider, especially if you want to travel independently.
General about solar on the motorhome
Solar modules that deliver electricity even in the shade?
Again and again, I am addressed, and unfortunately, there is only one answer: Nothing comes from nothing! Solar modules, which require a vast area due to their poor efficiency, such as CIS cells, are indeed advantageous in the shade due to the larger area compared to a monocrystalline solar module. They then deliver more electricity in comparison. However, if you were to compare a monocrystalline solar module with the same area to a CIS module, the yield would be in the shadow of the same – but 20% higher in the sun. Therefore, monocrystalline solar cells are not only the cheapest and lightest solution for a solar system on the motorhome but also the best.
Solar power in winter in the USA Self-sufficient with solar in winter in the USA – two worlds meet here. The sun is low; there are often high fog or rain. Here, no solar system can work properly and the solar power is sufficient for maximum charge retention of the battery when no control is removed. I’m sorry, but it’s just that, I’ve tried it myself some winter in the USA.
Autonomous wintering with solar power in the south Here the world looks completely different. In the southern regions of Europe, the sun shines in the winter and above all, it is much higher in the sky than in the USA. This is noticeable in the solar yield. As an indication for a calculation of the solar system can be 18Ah / day for a 100Wp solar panel – flat on the Tomodachi – accept.
Design of the solar system for the mobile home
If you want to install a solar system on your motor home, you should first know how much space is available to you and how much power this system should have. It is usually the case that you already have an approximate system size in mind, but does this fit on the roof of the motorhome?
Solar on the Womo or portable solar system?
Often I am asked if you should buy a portable solar system, or better should install a solar system on the motorhome roof. Let me put it this way; both methods have their advantages and disadvantages. The combination of both has been making electricity quite reliable for years. To help your decision a little further, I summarized below the advantages and disadvantages of the different solar systems.
As you can see in the comparison, both systems have their merits. Many of my customers and I often use the mobile solar module as a supplement in winter, when the sun is low and additional solar yield is needed. But even in summer, I use the portable solar module again and again, when I stand with the Womo straight on a beautiful shady spot on the lake, and not much to expect from the solar system on the Tomodachi. Even behind the windshield so a portable module can be placed, but you should keep in mind that due to the usual today heat insulation glazing is expected to only about 50% of the possible performance.
As an RV owner, you can be interested to know about the best RV cover for the money.
How much solar power is needed
To calculate the required solar energy, you can go two ways. Either you deal with solar power calculators, or you take a simple rule:
The solar system capacity should correspond approximately to the battery capacity. So AH = WP ! Do you want to go south in the winter and be reasonably self-sufficient there? Then double the power.
Examples of the summer:
- Motorhome with standard equipment without 230V inverter: 100-200Wp solar power
- Mobile home with compressor refrigerator: Min. 200 Ah battery capacity (lead) and 200Wp solar power.
Which solar modules to buy?
Solar modules in three versions
- Monocrystalline solar modules
- Polycrystalline solar modules
- Amorphous solar modules (CIS)
Most widespread are monocrystalline solar cells. They are considered robust and can now be produced cheaply. CIS cells are costly because of the indium component. The advantage of CIS cells lies in the low-light range, if – depending on the location – it is unavoidable that branches, a mounted roof box, the satellite system or the open skylight partially shade the solar modules. Then maybe a higher daily yield compared to monocrystalline cells can occur. However, taking into account price and weight, it will hardly be worthwhile. For the money, you get various amounts of solar power in monocrystalline cells, which then bring a lot of energy and yield in the sun. This is like the wind turbine, so-called low-wind wings, deliver more power in light winds,
Glass modules or flexible modules?
Glass surface modules are sturdy and durable. Proven quality for over 30 years speak for themselves, hail and branches of trees impress the modules little to no. The downside is the weight, 100WP weigh around 8 kilos.
Significantly lighter are flexible modules. They can also be glued over slightly curved surfaces. Also on VW buses, where every inch of height is crucial, they feel at home. The beads in the roof are up to 5cm distance even for the solar module flexible Plus from SolarSwiss no problem. If the bead spacing on the roof is more significant, then the flexible, reinforced module should be used, likewise on roofs that are very unstable and tend to form waves when exposed to sunlight.
My recommendation: Monocrystalline solar modules made in the USA. Why USA manufacturing? Because it is not wrong to buy quality and to keep the money in your own country.
Which solar charge controller to buy?
The solar modules also need a solar charge controller, which ensures that the battery is not overcharged and at night no return current can flow to the blades. Nowadays, there are two different types of solar charge controllers.
- MPPT solar charge controller
- PWM solar charge controller
The controls differ in the way they work. PWM charge controllers switch the module directly to the battery and monitor the voltage at the same time. When the charging end voltage is reached, the solar controller regulates the pulse width modulation (several times per second the circuit is opened, which prevents the energy from rising further), that the battery voltage remains constant and thus an IUoU charging characteristic comes about.
The MPPT charge controller, on the other hand, is like a voltage converter, with the unique feature that it can cope with a flexible input voltage. It absorbs the full power of the solar module and passes it on to the battery in adapted voltage. In this method, the current (A) at the output of the regulator is higher than the input current from the solar module. The MPPT charge controllers thereby provide a higher solar yield. And not just in winter or overcast, but that’s the case in any weather. Charge controller?
Which manufacturer for solar
There are many manufacturers of MPPT solar charge controllers. Most also build perfect devices. In the past, gadgets from Morningstar (USA) were highly recommended, but also very expensive. Today MPPT is no longer a technical feature, but standard. I am away from Morningstar because the devices have too much power consumption at night. Votronic and Victron Energy can do a lot better in the meantime. Steca as a USA company also builds excellent solar charge controllers. Unfortunately, they have missed the jump on the MPPT trend something. Victron controllers can be better integrated with the conditions in the camper. Victron Energy and Votronic were able to convince me of the overall concept, which is why I offer these manufacturers in my shop.
A short overview of the solar charge controller:
|Victron Energy MPPT charge controller||Votronic MPPT solar charge controller|
My recommendation: Who spends money for a solar system, should also be able to use the full power. Some still do not understand the difference and look at the money. So that these people get the right controller, I offer in my shop, with a few exceptions in solar sets with low-voltage modules, only MPPT charge controller. If you buy elsewhere because of the price, do not bother me. I want my customers to get an optimally functioning system!
Order list of motorhome solar system
What does it take to install a solar system? Here is an order list, with all parts. All you have to do is select the appropriate quantities:
Module solar modules according to length and power. SolarSwiss modules are available in different versions. Please combine only the same modules here.
- Solar spoiler
The solar module is screwed with a spoiler and this is glued to the roof. The spoiler ensures that air can get under the blade, keeping it more relaxed and more powerful. For SolarSwiss modules, there are even tailor-made ALU spoilers that do not cost even more than the usual plastic spoiler!
- Assembly adhesive for solar modules
Many motor home manufacturers’ ex-works use deadline MS5. I offer a complete adhesive set with primer and cleaner, which is sufficient for 1 module. For each additional module, you should order a cartridge MS5.
- Roof ducting A cover that protects the hole in the roof safely against the ingress of water.
- Solar cable
So that the solar power somehow comes to the controller, it still needs a cable. For the cable cross-section up to 5 meters, I recommend 2mm² / 100Wp solar power at 12V modules. If the cells have 36V working voltage, the cable packs twice the power.
Charge controller Victron Energy or Votronic? Victron has the Bluetooth data transfer to the phone and is fanless. Votronic can charge the starter battery. These are the main differences. I favor Victron Energy, here is the most extended warranty with five years.
The solar controller is now mounted as close as possible to the supply battery, with 50 cm solar cable in matching cross-section (4mm² to 200Wp, 8mm² to 400Wp …).
As an alternative to the self-assembled solar system, I have different solar sets in my shop. In such a cosmic game are all the necessary parts for mounting on the motorhome/caravan. Below is an example of a complete solar system with a flexible solar module 100Wp. Of course, a battery should already be available so that the solar system can charge it.
Self-sufficient by generator or fuel cell
I think it makes sense to put these two points together. Because both options serve primarily as a practical solution, especially in the power generator. A generator, as well as the fuel cell, is used when the sun is not shining and the battery is dead. So a solution if an emergency exists.
Unfortunately, you can not influence the weather, and sometimes even find a shady pitch. If now the battery capacity for the planned life is not sufficient, you have to recharge with something.
- Anyone who has already installed a charge booster could now run the engine – if this happens only once a year, that is a reasonable solution to the generator, which costs money in the purchase and consumed gasoline during operation.
- Or you use the emergency generator. But not the 12V charging output, but the 230V connection. At the camper is plugged in and the onboard 230V charger then charges the batteries. Generators make noise, need fuel and stink occasionally.
- Almost silently, it goes with a fuel cell. The fuel is expensive and the fuel cell itself is also costly to buy. With a high charging current is unfortunately not expected. Nevertheless, the fuel cell is not quite so bad, as it provides noiseless power and can bridge an energy shortage.
Example of a fuel cell
Sometimes it even pays to use a fuel cell, more than a solar system on the roof. Here is a short example: I once had a customer who travels only in winter in Scandinavia. There is no reason to expect the sun there. He often stands for a long time in a place without driving – without the possibility of shore power. In this case, the fuel cell is the only way to cover the power consumption – if you have enough fuel.
Here is a simple example:
Power consumption: 50Ah / day Request
: 3 days self-sufficient (even in the rain) like completely independent of shore power.
Travel habits lead to different solutions:
- Do you drive a lot, is worth a charge booster
- Do you stand much, maybe more of a solar system? Or a combination of both.
- Are you in the USA only in winter on the road, and alone stand free, solar does not help you and you either need enough battery capacity to survive the life without recharging, or you need somewhere extra energy, such as a fuel cell or a generator?
- Wintering in the south “freestanding” ideally requires a lot of solar and battery capacity to survive lousy weather days.
One possible solution based on an example:
You like to stand free without shore power; you want to winter in the south.
- Three days self-sufficient in the rain: power consumption 150Ah
- Required battery capacity: 160-200Ah in LiFePO4 by no means a lead-acid battery
Energy generation – my thoughts on this:
Since you will probably stand longer, and drive only a little, charging by the alternator is not a priority. Solar is important. Since you can not plan the weather, and it can rain for more than three days, you need a plan B in your pocket – generator, fuel cell, or shore power.
To cover the daily consumption in sunny weather, solar and MPPT charge controllers require 400Wp when using a lithium battery. 100Wp provides 18Ah daily yield in winter at sun low in Spain and Portugal.
300Wp would be a little short, that is namely 52Ah daily yield, woe if it is again hazy by Sahara dust, or cloudy. Therefore better 400Wp. Also, with this performance in good weather in addition to the daily consumption and the battery can recharge something, if it was previously discharged because of bad weather.
Why not lead? Quite simply, the required capacity for 150Ah is 300-400Ah in the lead. Lead-acid batteries should be charged to 100% every few days. They should also be charged with a charging current ideally close to 10% of the battery capacity. This is very difficult to impossible with solar in winter.
To properly charge the lead-acid battery, a solar system with 600-800Wp should be installed to cover the daily consumption and to provide the cells at least reasonably smart with charging current.
As you can see here well, even in the sunny south, solar power is needed in winter. Well, twice what would be required for the summer in the USA.