newbie question solar food truck build

[hasimodo]

I am helping my friend install a solar setup in a food truck. This is a unique setup and I wanted to get some help from the experts. The food truck will be running in 3 hour stints twice a day. the times the food truck will be open is from 11-1 pm and 4-7 pm. all other times the food truck will return to base and plug in to the grid to keep batteries topped off. There will also be a generator installed to supplement the system if needed. The food truck is a whopping 27 ft so there is room enough for 6 panels on top and a large battery bank custom mounted in a box connected to the frame. Now to get down to brass tacks:

The equipment we are considering:
6-trina solar 290 watt 72 cell 24v panels (already purchased and mounted these)
dual magnum power center (as seen on popular solar website) 8000 watts
9 to 12- 250ah AGM batteries (this is where I need help the most)
Either outback flexmax or midnite solar mppt controller
6000-8000 watt generator

Sounds ambitious right?

The power consumption will be roughly 2-4000 watts per hour... yep per hour. for 3 hours at a time. the highest possible draw will be 6000 watts if everything came on at the same time.

Now I understand that a system like this should handle the load for maybe 2 hours until the generator kicks on. but of course I could be wrong and that is why I'm here. Just so we are clear, I have only mounted the panels and have not purchased any other equipment. Also please understand that this isn't to just save money from running a generator for long periods of time. I know that the cost per watt would probably be less if I went generator only, and there is much more behind this project than just economics.

I do appreciate any input and am also appreciative of the time that some of you take to help others with queries such as these. I hope this interests some of you enough to help me size this system correctly.

[hasimodo]

After some research I think the xantrex xw system with the gen support would work better in this situation. Hope to get some feedback. Thanks

[Sunking]

I think you are in for a huge unpleasant nasty expensive surprise. Assuming you are pulling 2500 watts average which is a bit on the low side for a food truck with all the refrigeration and and air conditioning for 6 hours = 15 Kwh. At best under ideal conditions which your panels will never be in can only generate 5 Kwh in a day. You will be lucky to generate 3 to 5 Kwh in a day.

To use 15 Kwh of power from batteries without destroying them in less than a year is going to require a 48 volt @ 1000 AH weighing some 3000 pounds and if using AGM costing some $15,000 to $20,000 and need replacing every 3 to 4 years.

The physics are not with you. To generate 15 Kwh of usable power with panels on a Food Truck would take 6000 watts of solar panels broken into two panel systems with each having two 60 amp charge controller, charging a 48 volt 1000 AH battery. A do not even dare or think about parking the truck anywhere near a tree or building casting shade on the truck. You will also need to keep that over sized 10 Kw generator fueled up with a 120 amp 48 volt charger ready to go.

Smart money and business decision is just a good LPG generator and ditch the solar before you waste and loose any more money.

[hasimodo]

I think you are in for a huge unpleasant nasty expensive surprise. Assuming you are pulling 2500 watts average which is a bit on the low side for a food truck with all the refrigeration and and air conditioning for 6 hours = 15 Kwh. At best under ideal conditions which your panels will never be in can only generate 5 Kwh in a day. You will be lucky to generate 3 to 5 Kwh in a day.

To use 15 Kwh of power from batteries without destroying them in less than a year is going to require a 48 volt @ 1000 AH weighing some 3000 pounds and if using AGM costing some $15,000 to $20,000 and need replacing every 3 to 4 years.

The physics are not with you. To generate 15 Kwh of usable power with panels on a Food Truck would take 6000 watts of solar panels broken into two panel systems with each having two 60 amp charge controller, charging a 48 volt 1000 AH battery. A do not even dare or think about parking the truck anywhere near a tree or building casting shade on the truck. You will also need to keep that over sized 10 Kw generator fueled up with a 120 amp 48 volt charger ready to go.

Smart money and business decision is just a good LPG generator and ditch the solar before you waste and loose any more money.

One thing to consider, this truck will be plugged in to shore power and charging the bank via a quick charger for 3 hours between stints and then all night after 7 pm. The solar is there to just be supplemental during the initial use of the truck, even though will only provide a fraction of the required power. What I'm really looking for is appropriate battery bank sizing for 3 hours of use, and what inverter and battery type will work best for this application. I appreciate your response and hope these factors change your calculations.

[Sunking]

One thing to consider, this truck will be plugged in to shore power and charging the bank via a quick charger for 3 hours between stints and then all night after 7 pm. The solar is there to just be supplemental during the initial use of the truck, even though will only provide a fraction of the required power. What I'm really looking for is appropriate battery bank sizing for 3 hours of use, and what inverter and battery type will work best for this application. I appreciate your response and hope these factors change your calculations.

It does not changer a thing with the battery. $15,000 and 3000 pounds. Replace every few years. The solar panels, controller, inverters just add more cost and weight that does not do anything for you. I am sorry as I know that is not what you want to hear, but it is factual. You have a business to run, the only reason to go into business is to make as much money as possible. There is no other reason. That means keeping your cost down and getting the most out of your investment.

Look around at other successful food trucks. Refrigeration, lighting, ventilation (exhaust hood), blenders, microwaves, and air conditioning is ran on generators. Cooking is done with LPG and as fuel for the generator.

If you want to be the best, ask the pros and do what they do. They do not use solar as the power requirements are way beyond batteries and solar panels capabilities. It demands fossil fuel energy density. To replace 1 single pound of LPG with genny takes 50 pounds of battery taking up 30 times more space. You simply do not have the space required or can afford to haul the extreme weight.

Food Truck FAQ
Build Food Truck
How To Power Food Truck Without Generator


Use this Link to determine what size generator you will need.

Good Luck

[Mike90250]

Sadly, solar is not a good option for food trucks. What may be OK, is to install a cold plate freezer system like are used on ocean boats, with a large thermal mass, as you drive, the engine runs a compressor and quickly chills the plate down for period on non-engine usage. Don't know if that will keep your food cold enough between stops or not.

But the required weight and volume of batteries will eat into your food payload, and tie up a lot of $. May as well forget the solar part, and just use plug in to recharge, or better still, a small inverter generator like the honda EU2000. Very quiet.

[Sunking]

May as well forget the solar part, and just use plug in to recharge, or better still, a small inverter generator like the honda EU2000. Very quiet.

Mike he has a 6 Kw demand....

He is running more than a refrigerator and lighting. Cummins Onan makes the generators most commercial Food Trucks use and vary in size from 2.5 to 6.5 Kw in LPG, 2.8 to 7 Kw in gasoline, 5 to 20 Kw in diesel, and 5 to 25 Kw in hydraulic models. All are very quite with little vibration.

Every Food Truck I have seen has a On Board generator, and a 240/120 60 amp Shore Power Pig Tail when they are in an area with electrical connections, or at home base to keep the refrigerators cold until next day use.

[hasimodo]

Thank you everyone for your input. Looks like we will be scrapping the idea for now based on what we've learned here. Maybe we can re-look at the idea when tesla releases their home battery bank. The ROI wasnt really much of a factor in all this, it was more of the good PR, because I live in a state where air quality is the number one issue. It would be something that would get the company building the food truck some good publicity through news outlets and give them a leg up on the competition. Food trucks are trending big right now so any sort of extra PR is a big advantage.

The weight of the battery bank is the biggest issue, and what would hold us back. The tesla home battery bank will solve that, and it looks like you can get 10 kwh of storage for about $13,000.

Again thank you guys for your input.

[Wy_White_Wolf]

Sadly, solar is not a good option for food trucks. What may be OK, is to install a cold plate freezer system like are used on ocean boats, with a large thermal mass, as you drive, the engine runs a compressor and quickly chills the plate down for period on non-engine usage. Don't know if that will keep your food cold enough between stops or not....

Not going to pass FDA or state regulations. I run into this with people wanting to sell meat or eggs at farmers markets. Regs require the frig/freezer to have a constant power supply.

WWW

[Amy@altE]

I'm going to chime in, as I have solarized my sister's hot dog stand in MA. However, she does not have nearly the loads you have, so we have a small system on it. But I'm very familiar with at least the MA food truck regulations.

If you already have the panels mounted, and are doing this for PR, perhaps a hybrid solution would work. Don't run all of the loads off the battery bank. Determine if there are some high power draw items that are intermittent, so you can run some items off the solar charged battery bank, and then turn on the generator when needed. Do a loads list of all of the equipment, how many watts it draws and how long it is on, and you may be able to size a smaller system that will do some of the work.

[Amy@altE]

Another of my customers, I.C. Treats, a solar powered ice cream boat. http://photos.gloucestertimes.com/ke...2014/i-KxG6zMS

Again, small loads, we just did a DC freezer, but possible if you break the loads up.

[SunEagle]

I'm going to chime in, as I have solarized my sister's hot dog stand in MA. However, she does not have nearly the loads you have, so we have a small system on it. But I'm very familiar with at least the MA food truck regulations.

If you already have the panels mounted, and are doing this for PR, perhaps a hybrid solution would work. Don't run all of the loads off the battery bank. Determine if there are some high power draw items that are intermittent, so you can run some items off the solar charged battery bank, and then turn on the generator when needed. Do a loads list of all of the equipment, how many watts it draws and how long it is on, and you may be able to size a smaller system that will do some of the work.

I agree with you Amy. He could build a solar/battery system to run some of the smaller lighting or sound system loads. This would allow him to use a smaller generator for his cooking/refrigeration loads.

What I do not like is the idea of promoting a food truck as "solar powered". It would be false advertising. A lot of people would think they are not burning fossil fuel because they are using "free" solar power. That may make people feel warm and fuzzy but it would be a lie.

[Sunking]

If you already have the panels mounted, and are doing this for PR, perhaps a hybrid solution would work. Don't run all of the loads off the battery bank. Determine if there are some high power draw items that are intermittent, so you can run some items off the solar charged battery bank, and then turn on the generator when needed.

Sure you could do that. Especially if you are the one selling the equipment as you just more than doubled the electrical equipment cost having 2 separate systems.

PR is easy and cheap if you already have the panels. Mount the panels and use them as the pop-up eve for the customer service window. No one would see them on top. They just don't get connected to anything. The public is stupid enough to fall for it. If they ask why they hear a motor running tell them it is for the refrigeration which would an accurate true statement.

Here is a true story that will make you Happy Happy if you like PR. Good ole Walmart is installing huge solar systems on many of their stores. I designed and built one in Plano TX, a 550 Kw system. The city, and electric rate payers paid for every bit of it. Walmart gets to use the PR and saves them $200/day in electric cost to pay dividends to stock holders. It netted me a nice check on a $4M job of 15% T&E. That model is repeated everywhere they put in solar and you pay for it rather you like it or NOT. If the city and electric company will not pay for it, they don't install it. Brilliant PR work.