Solar PV RV

The following guest post on solar pv power for an RV is written by a friend of Mapawatt, Christine Walker and her husband.  When she told me what they had been up to I made her write the following as I knew it was perfect content for Mapawatt.

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Solar Rocks!

It’s a phrase we’ve been giddily saying often this last week. We finally bit the bullet and invested in solar and we are obviously very happy with our decision. So what pushed us over the edge? Why are we loving solar?

First a little background. We’ve been traveling the country the last year in our 40’ motorhome. We’ve mostly visited national parks and forests, state parks, etc and many of those places don’t have electric hookups. So what does one do when in the middle of nature, far from a convenient power plug, and you need a little juice? If you don’t have solar you fire up your loud and stinky generator (if allowed and only during designated hours while in campgrounds.)

Recently we’ve been spending more time out in the boonies with fellow RVers who have solar. Being the only one having to the fire up the generator and ruin the peace and tranquility is a bit of a bummer. Add to that seeing their setups and how much power they are able to produce, our envy grew. After weighing the pros and cons - we decided it was time to join the solar club!

So what steps did we take to figure out what to get?

First we noted what we already had in our motorhome:

• 4 Trojan t-105 batteries
• Xantrex 2000 watt inverter

Next we created a spreadsheet that listed our appliances, electronics, lights etc and how much power they consume. This would be used to determine how many panels/watts we would need to cover our power needs. We researched and chatted with friends to find out what they had (panels, manufacturer, etc.)

It was when we stared in our battery bay with its mess of unlabeled wires and looked at our inverter that we decided we were not comfortable wiring in the shunt necessary for including a battery monitor. So we decided to have our solar system installed instead of doing it ourselves. Our installer was a great help in answering our questions and providing recommendations, on top of doing a great job.

In the end we settled on:
• Four 150 watt panels for a total 600watts.
• UV resistant 9 gauge wire on top going to a combiner box with 4 gauge wire in a straight drop to the controller.
• 60 amp Morningstar Tristar MPPT Controller (which would allow us go up to at least 800 watts in the future if needed) which was placed beside the batteries.
• Trimetric battery monitor 2025 from Bogart Engineering

All totaled, materials cost around $3300.

We also built tilt bars for the panels which based on our location and the time of year allow them to get more direct sunlight which means more power creation!

It has been great fun watching our monitors to not only see how much power we are making but also how much power we are using. For power creation, post tilt bars and sunny days we are making 20amps by around 8am and 30amps by 9am! Max we’ve seen is around noon-ish making 44 amps. We’ve been making so much power (and not using that much) that we are quickly going to an absorb state. It will be interesting to see how we fare on cloudy days. So far our 600 watts is perfect and plenty for us.