Solar upgrade May 30, 2018, 02:00:03 pm Hi-My solar inverter needs to be replaced. I have the standards 2 panel roof solar panels.If I wanted to be completely self-sustained (AC, fringe, microwave ect) what would be required?Thanks in advance.Mark
Re: Solar upgrade Reply #1 – May 30, 2018, 02:21:57 pm For AC about a 3000W inverter, assume 90% efficiency, that means at least 4000 W of panels, or 20 200W panels. That does not include the battery bank for storing for non-full-sun operation. Others who have done this usually pull a low trailer for battery bank, inverter, and fold-up solar banks, and connect to rig with a 30A cord.Steve
Re: Solar upgrade Reply #2 – May 30, 2018, 03:37:28 pm Quote from: NADAZE! - May 30, 2018, 02:00:03 pmMy solar inverter needs to be replaced. I have the standards 2 panel roof solar panels.If I wanted to be completely self-sustained (AC, fringe, microwave ect) what would be required?I doubt it is possible to be totally self contained using just solar unless your needs are minimal and the roof is covered in panels..With 400-watts of solar panels, we have a hard time keeping the battery up in mid-winter. Overcast and rainy weather provides next to no solar power . The low, mid-winter sun, along with the short days, does not provide enough energy to keep the batteries up, especially with high power appliances, such as a big inverter, used to power a microwave and other high wattage devices.Be prepared to use your generator a lot during the dark months, install the largest converter possible to minimize generator run time. To get your money's worth out of the additions, be prepared to upgrade all the wiring and fusing in the charging circuits, plus the controller, when adding multiple panels.It can get expensive fast especially if you do not do the install yourself. Larry 3 Likes
Re: Solar upgrade Reply #3 – May 30, 2018, 04:01:12 pm Wow.I didn't realize how much would be involved in this sort of upgrade.Without using the ac how many panels would you recommend?
Re: Solar upgrade Reply #4 – May 30, 2018, 04:26:27 pm This fellow has considerable personal hands on experience and his blog contains solid information on practical RV solar / battery / inverter. You'll find answers to all your questions there.HandyBob's Blog « Making off grid RV electrical systems work 2 Likes
Re: Solar upgrade Reply #6 – May 30, 2018, 04:39:56 pm Mark, that is a very complex question. If you have no overnight loads, if you run your generator to use the microwave, if you run the refrigerator on propane, minimal TV and light usage, you are probably ok with two panels and two batteries. Now let me give you the other extreme - me. I use a CPAP machine all night. I watch TV from around 5 to around 10 every night. I have a remote satellite dish and use a DVR, which is drawing power even if I am not watching TV. I use propane for my refrigerator and I run the generator to use my microwave. I have 5 solar panels on the roof and 6 AGM batteries for a 660 amp-hour capacity. Overnight, my batteries go from full charge to 80% charge. I run the gennie for half an hour in the morning on a sunny day to give the system a jump on things, and my batteries hit full charge mid- to late afternoon.The point of all that is to illustrate that there can be a very wide range of power needs based on how you use your RV. There is also a large variety of charge rate depending on time of year and location. To determine what you need to be self-contained, you have to add up all the things you use that run off the battery system, the wattage they draw, and the hours they are in use. That gives you your daily watt-hour power needs. We can't do that for you. You will have to figure that out. Once you know the watt-hours, divide by 12 to get the amp-hours you need. Remember that you should plan on using up to 1/3 of your battery capacity on a daily basis. The more you draw the batteries down, the less time they will last. I typically use about 120 to 140 amp-hours overnight. That is a safe load for my 660 amp-hour battery bank, as evidenced that the original bank lasted 9 years and was still in good shape.The above tells you how much battery capacity you need. As to how many solar panels, the rule of thumb has been 1 panel per battery. The further south you are, the more efficient your panels will be. Conversely, if you are habitually in the northlands, you will get less from them. The east tends to be more cloudy than the southwest. In Oregon and Washington, west of the Cascades, don't expect to see much sun from October to late May. For me to not have to use my generator, I would need a sixth panel up there, but remember - I am an electricity hog.Everyone's needs are different. You will have to determine your needs and your travel patterns before we can be much help.Ken F in WY (under a cloudy sky) :-) 7 Likes
Re: Solar upgrade Reply #7 – June 01, 2018, 11:12:26 am I'm at the other end of the extreme.My battery bank is only 152AH. I have two 100W solar panels.None of my appliances run off of 115VAC. I don't have a microwave, TV, or most of the other battery-draining appliances.All of my lights are LED. I have a few parasitic drains like the propane detector that don't amount to much.The biggest drains on my battery are the propane refrigerator's control board, the water pump, and the furnace fan. The furnace is rarely used, and a "buddy heater" suffices.I have a lot of USB outlets to charge iPads and iPhones, which is the main ways we consume media in the RV. We don't have an inverter. Our small 2000W generator has never been used outside of a short test run in the driveway. It all really boils down to how much you "need". You can certainly throw a lot of money at solar installers and they will gladly take it, or you can educate yourself and figure out exactly what you need before you go there. If you're handy and have some experience with electrical wiring, it isn't rocket science. It just takes research, planning, and care. 1 Likes
Re: Solar upgrade Reply #8 – June 01, 2018, 03:30:33 pm Even more extreme. One 100w panel from the factory, 2 standard trojan wet cells. But, when off the grid, we mostly use three Luci lights for general interior lumination, and headlamps for reading. Before leaving home, I download to our iPad as many shows/movies as I can from Netflix, and you can watch for hours before recharging. Morning coffee is made with a kettle on the stove and a Melita drip carafe. With the house batteries generally only taking care of the fridge controls, pump and other systems, you can go for quite a while in dodgy sun conditions with this extreme frugal mode. Obviously, this doesn’t work for most, but it shows that the range of power usage can have even lower limits. — Jon 2 Likes
Re: Solar upgrade Reply #9 – June 02, 2018, 02:47:30 am HandyBob offers some useful information, but he is extremely opinionated, and his site is a mixed bag. When he tells you that it's vital to have adequately sized wire, believe him. When he tells you that MPPT solar controllers are a waste of money, don't. It's hard to tell the wheat from the chaff on Bob's site, because he's very sure of his opinions even when they are questionable.But back to your question, Mark. You've gotten good advice from people here, and you now have an idea of the wide range of lifestyles and power systems you can choose from. A lot depends on your personal preferences (and your budget!), but I'll make a broad generalization that may be helpful: if you don't try to power the air conditioner and the microwave oven (or other electrical cooking appliances), you can probably get by with a couple hundred watts of panels and a couple hundred amp-hours of batteries. Alaska Mike, Jon & Loni can testify to that, and they're not alone.Maybe living without an air conditioner and microwave feels as if it would be too much of a sacrifice. Personally, I find the microwave easy to get along without. My current rig came with one, but I removed it because I wanted the drawer space it occupied for storage. I do just fine with my propane stove; there's nothing I could do in the microwave that I can't do on the range or in the oven. As for air conditioning, I have one but seldom use it--instead, I move northward or to a higher altitude and open my windows. I can usually stay comfortable that way. 3 Likes
Re: Solar upgrade Reply #10 – June 02, 2018, 12:52:02 pm Quote from: Andy Baird - June 02, 2018, 02:47:30 amAs for air conditioning, I have one but seldom use it--instead, I move northward or to a higher altitude and open my windows. I can usually stay comfortable that way.Amen. If you're not constrained by other obligations, remote higher altitude options will get you cooler and tend to be much less crowded than more popular sites. Only dire necessity will have us fire up the generator to run the AC. However, doing so for 10 minutes or so it takes to run the microwave is a pretty good alternative to a major inverter and electrical upgrade just for that purpose. For early morning or late evening needs of the microwave, find alternative ways that will not disturb neighbors.Steve
Re: Solar upgrade Reply #11 – June 02, 2018, 05:18:14 pm Quote from: Andy Baird - June 02, 2018, 02:47:30 amMaybe living without an air conditioner and microwave feels as if it would be too much of a sacrifice. Personally, I find the microwave easy to get along without. My current rig came with one, but I removed it because I wanted the drawer space it occupied for storage. I do just fine with my propane stove; there's nothing I could do in the microwave that I can't do on the range or in the oven. I measured LD cabinet doors for years, hoping to find the right size Factory door to cover the microwave compartment, without success.In most LDs, the inside of the microwave cabinet contains a lot of wasted space and removing it would provide much additional storage. 99% of the time, in our LD, the microwave is nothing more than glorified, undersize bread box.As Steve pointed out, most use the microwave so seldomly, utilizing the generator to power it is a better choice than an expensive inverter.Larry
Re: Solar upgrade Reply #12 – June 02, 2018, 09:27:48 pm Quote from: Andy Baird - June 02, 2018, 02:47:30 am"HandyBob offers some useful information, but he is extremely opinionated,..." I see you've been to the site! Yep, he's even opinionated about being opinionated! <smile>
Re: Solar upgrade Reply #13 – June 03, 2018, 09:31:42 pm 460 Ahr of battery storage, 315W solar panel with MPPT control, no generator. So far when staying in the Northwest this winter by the time the battery bank got down to 65% after 2 weeks of no sun days we are on the move the alternator tops of the batteries. We have a small Honda and a soft starter(not just a capasitor) on the AC on hot desert trips.
Re: Solar upgrade Reply #14 – June 04, 2018, 11:05:32 am Quote from: Craig P - June 03, 2018, 09:31:42 pm We have a small Honda and a soft starter(not just a capasitor) on the AC on hot desert trips.An option, if you have no on-board generator. But, as Andy can testify, even a securely chained-up Honda can disappear quickly...Steve
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